imagecopyresampled

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

imagecopyresampled重采样拷贝部分图像并调整大小

说明

bool imagecopyresampled ( resource $dst_image , resource $src_image , int $dst_x , int $dst_y , int $src_x , int $src_y , int $dst_w , int $dst_h , int $src_w , int $src_h )

imagecopyresampled() 将一幅图像中的一块正方形区域拷贝到另一个图像中,平滑地插入像素值,因此,尤其是,减小了图像的大小而仍然保持了极大的清晰度。

In other words, imagecopyresampled() will take a rectangular area from src_image of width src_w and height src_h at position (src_x,src_y) and place it in a rectangular area of dst_image of width dst_w and height dst_h at position (dst_x,dst_y).

如果源和目标的宽度和高度不同,则会进行相应的图像收缩和拉伸。坐标指的是左上角。本函数可用来在同一幅图内部拷贝(如果 dst_imagesrc_image 相同的话)区域,但如果区域交迭的话则结果不可预知。

参数

dst_image

目标图象连接资源。

src_image

源图象连接资源。

dst_x

目标 X 坐标点。

dst_y

目标 Y 坐标点。

src_x

源的 X 坐标点。

src_y

源的 Y 坐标点。

dst_w

目标宽度。

dst_h

目标高度。

src_w

源图象的宽度。

src_h

源图象的高度。

返回值

成功时返回 TRUE, 或者在失败时返回 FALSE

范例

Example #1 简单的例子

这个例子会将图像调整为原有尺寸的一半。

<?php
// 这个文件
$filename 'test.jpg';
$percent 0.5;

// 内容类型
header('Content-Type: image/jpeg');

// 获取新的尺寸
list($width$height) = getimagesize($filename);
$new_width $width $percent;
$new_height $height $percent;

// 重新取样
$image_p imagecreatetruecolor($new_width$new_height);
$image imagecreatefromjpeg($filename);
imagecopyresampled($image_p$image0000$new_width$new_height$width$height);

// 输出
imagejpeg($image_pnull100);
?>

以上例程的输出类似于:

输出的例子:简单的例子

Example #2 按比例对图像重新采样

这个例子会以最大宽度高度为 200 像素显示一个图像。

<?php
// 源文件
$filename 'test.jpg';

// 设置最大宽高
$width 200;
$height 200;

// Content type
header('Content-Type: image/jpeg');

// 获取新尺寸
list($width_orig$height_orig) = getimagesize($filename);

$ratio_orig $width_orig/$height_orig;

if (
$width/$height $ratio_orig) {
   
$width $height*$ratio_orig;
} else {
   
$height $width/$ratio_orig;
}

// 重新取样
$image_p imagecreatetruecolor($width$height);
$image imagecreatefromjpeg($filename);
imagecopyresampled($image_p$image0000$width$height$width_orig$height_orig);

// 输出
imagejpeg($image_pnull100);
?>

以上例程的输出类似于:

输出例子:按比例对图像重新采样

注释

Note:

因为调色板图像限制(255+1 种颜色)有个问题。重采样或过滤图像通常需要多于 255 种颜色,计算新的被重采样的像素及其颜色时采用了一种近似值。对调色板图像尝试分配一个新颜色时,如果失败我们选择了计算结果最接近(理论上)的颜色。这并不总是视觉上最接近的颜色。这可能会产生怪异的结果,例如空白(或者视觉上是空白)的图像。要跳过这个问题,请使用真彩色图像作为目标图像,例如用 imagecreatetruecolor() 创建的。

参见

imagecopyresized() - 拷贝部分图像并调整大小

User Contributed Notes

julien at go-on-web dot com 02-Apr-2014 05:59
Windows does not accept floating width and height...

So, in "Example #2 Resampling an image proportionally", prefer :
<?php
if ($width/$height > $ratio_orig) {
  
$width = round( $height*$ratio_orig );
} else {
  
$height = round( $width/$ratio_orig );
}
?>
(used "round")
otherwise your image wont be resized.
kazuya 11-Mar-2014 11:24
<?php

$new_file
= img_resize("./img/", "test.jpg","copy_test.jpg",300);
echo
"<IMG src = '$new_file'>";

function
img_resize($path,$tmp_name,$new_name,$new_width){
    if (!
file_exists($path.$filename)){
        echo
"file not found!";
        exit;
    }
    if (!
is_writable($path)){
        echo
"error:permission denied!";
        exit;
    }
    list(
$width, $height) = getimagesize($path . $tmp_name);
   
$new_height = abs($new_width * $height / $width);
   
$image_p = imagecreatetruecolor($new_width, $new_height);
   
$image = imagecreatefromjpeg($path . $tmp_name);
   
imagecopyresampled($image_p, $image, 0, 0, 0, 0,
                       
$new_width, $new_height, $width, $height);
   
imagejpeg($image_p, $path . $new_name);
    return
$path.$new_name;
}

?>
sam at durosoft.com 18-Aug-2013 03:18
The ultimate smart image re-sizing routine. You provide the original image, and a desired width and/or height. The function will intelligently re-size the original image to fit, centered, within the specified dimensions. Either width or height can be omitted to have the re-size "lock" only on width or height. Fantastic for thumbnail generation. Designed to work with PNG's.

function resize_image_smart($orig, $dest_width=null, $dest_height=null)
{
  $orig_width = imagesx($orig);
  $orig_height = imagesy($orig);
  $vertical_offset = 0;
  $horizontal_offset = 0;
  if($dest_width == null)
  {
    if($dest_height == null)
    {
      die('$dest_width and $dest_height cant both be null!');
    }
    // height is locked
    $dest_width = $dest_height * $orig_width / $orig_height;
  } else {
    if($dest_height == null)
    {
      // width is locked
      $dest_height = $dest_width * $orig_height / $orig_width;
    } else {
      // both dimensions are locked
      $vertical_offset = $dest_height - ($orig_height * $dest_width) / $orig_width;
      $horizontal_offset = $dest_width - ($dest_height * $orig_width) / $orig_height;
      if($vertical_offset < 0) $vertical_offset = 0;
      if($horizontal_offset < 0) $horizontal_offset = 0;
    }
  }
  $img = imagecreatetruecolor($dest_width, $dest_height);
  imagesavealpha($img, true);
  imagealphablending($img, false);
  $transparent = imagecolorallocatealpha($img, 0, 0, 0, 127);
  imagefill($img, 0, 0, $transparent);
  imagecopyresampled($img, $orig, round($horizontal_offset / 2),
                                  round($vertical_offset / 2),
                                  0,
                                  0,
                                  round($dest_width - $horizontal_offset),
                                  round($dest_height - $vertical_offset),
                                  $orig_width,
                                  $orig_height);
  return $img;
}
wbcarts at juno dot com 19-Jul-2013 04:14
FOUR RECTANGLES

                  $src_image                                   $dst_image
+------------+---------------------------------+   +------------+--------------------+
|            |                                 |   |            |                    |
|            |                                 |   |         $dst_y                  |
|            |                                 |   |            |                    |
|         $src_y                               |   +-- $dst_x --+----$dst_width----+ |
|            |                                 |   |            |                  | |
|            |                                 |   |            |    Resampled     | |
|            |                                 |   |            |                  | |
+-- $src_x --+------ $src_width ------+        |   |       $dst_height             | |
|            |                        |        |   |            |                  | |
|            |                        |        |   |            |                  | |
|            |                        |        |   |            |                  | |
|            |                        |        |   |            +------------------+ |
|            |        Sample          |        |   |                                 |
|            |                        |        |   |                                 |
|            |                        |        |   |                                 |
|       $src_height                   |        |   |                                 |
|            |                        |        |   +---------------------------------+
|            |                        |        |
|            |                        |        |
|            +------------------------+        |
|                                              |
|                                              |
+----------------------------------------------+
hoangvu4000 at gmail dot com 27-May-2013 02:50
My complete function to resize an image  with exif data

<?php
function CreateThumbnail($pic,$thumb,$thumbwidth, $quality = 100)
{
        
       
$im1=ImageCreateFromJPEG($pic);
        if(
function_exists("exif_read_data")){
               
$exif = exif_read_data($pic);
                if(!empty(
$exif['Orientation'])) {
                switch(
$exif['Orientation']) {
                case
8:
                   
$im1 = imagerotate($im1,90,0);
                    break;
                case
3:
                   
$im1 = imagerotate($im1,180,0);
                    break;
                case
6:
                   
$im1 = imagerotate($im1,-90,0);
                    break;
                }
                }
        }
       
$info = @getimagesize($pic);
       
       
$width = $info[0];
        
       
$w2=ImageSx($im1);
       
$h2=ImageSy($im1);
       
$w1 = ($thumbwidth <= $info[0]) ? $thumbwidth : $info[0]  ;
        
       
$h1=floor($h2*($w1/$w2));
       
$im2=imagecreatetruecolor($w1,$h1);
        
       
imagecopyresampled ($im2,$im1,0,0,0,0,$w1,$h1,$w2,$h2);
       
$path=addslashes($thumb);
       
ImageJPEG($im2,$path,$quality);
       
ImageDestroy($im1);
       
ImageDestroy($im2);
        
}
?>
alex-thennstaett-remove at gmx dot net 11-Nov-2012 02:06
Having updated GD-Library from 2.0.35-r1 to 2.0.35-r3 using negative numbers for $dstX or $dstY started to produce unpredictable results, such as inserting shrinked images and enlarging $dstH or $dstW all by itself. While it did work fine previously, one should avoid using or calculating negative numbers for imagecopyresampled from the beginning.
promaty at gmail dot com 18-May-2011 02:26
Here is my ultimate image resizer that preserves transparency for gif's and png's and has an option to crop images to fixed dimensions (preserves image proportions by default)

<?php
function image_resize($src, $dst, $width, $height, $crop=0){

  if(!list(
$w, $h) = getimagesize($src)) return "Unsupported picture type!";

 
$type = strtolower(substr(strrchr($src,"."),1));
  if(
$type == 'jpeg') $type = 'jpg';
  switch(
$type){
    case
'bmp': $img = imagecreatefromwbmp($src); break;
    case
'gif': $img = imagecreatefromgif($src); break;
    case
'jpg': $img = imagecreatefromjpeg($src); break;
    case
'png': $img = imagecreatefrompng($src); break;
    default : return
"Unsupported picture type!";
  }

 
// resize
 
if($crop){
    if(
$w < $width or $h < $height) return "Picture is too small!";
   
$ratio = max($width/$w, $height/$h);
   
$h = $height / $ratio;
   
$x = ($w - $width / $ratio) / 2;
   
$w = $width / $ratio;
  }
  else{
    if(
$w < $width and $h < $height) return "Picture is too small!";
   
$ratio = min($width/$w, $height/$h);
   
$width = $w * $ratio;
   
$height = $h * $ratio;
   
$x = 0;
  }

 
$new = imagecreatetruecolor($width, $height);

 
// preserve transparency
 
if($type == "gif" or $type == "png"){
   
imagecolortransparent($new, imagecolorallocatealpha($new, 0, 0, 0, 127));
   
imagealphablending($new, false);
   
imagesavealpha($new, true);
  }

 
imagecopyresampled($new, $img, 0, 0, $x, 0, $width, $height, $w, $h);

  switch(
$type){
    case
'bmp': imagewbmp($new, $dst); break;
    case
'gif': imagegif($new, $dst); break;
    case
'jpg': imagejpeg($new, $dst); break;
    case
'png': imagepng($new, $dst); break;
  }
  return
true;
}
?>

Example that I use when uploading new images to the server.

This saves the original picture in the form:
original.type

and creates a new thumbnail:
100x100.type

<?php
  $pic_type
= strtolower(strrchr($picture['name'],"."));
 
$pic_name = "original$pic_type";
 
move_uploaded_file($picture['tmp_name'], $pic_name);
  if (
true !== ($pic_error = @image_resize($pic_name, "100x100$pic_type", 100, 100, 1))) {
    echo
$pic_error;
   
unlink($pic_name);
  }
  else echo
"OK!";
?>

Cheers!
guru_boy87 at hotmail dot com 23-Jun-2010 01:52
Function to resize an image.

<?php
function resizeImage($originalImage,$toWidth,$toHeight)
{

    list(
$width, $height) = getimagesize($originalImage);
   
$xscale=$width/$toWidth;
   
$yscale=$height/$toHeight;

    if (
$yscale>$xscale){
       
$new_width = round($width * (1/$yscale));
       
$new_height = round($height * (1/$yscale));
    }
    else {
       
$new_width = round($width * (1/$xscale));
       
$new_height = round($height * (1/$xscale));
    }
   
   
   
$imageResized = imagecreatetruecolor($new_width, $new_height);
   
$imageTmp     = imagecreatefromjpeg ($originalImage);
   
imagecopyresampled($imageResized, $imageTmp, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

    return
$imageResized;
   

}
?>
seifer at loveletslive dot com 25-Oct-2009 02:27
Okay so I saw that others have posted this already but I just messed around and made it so figured I would share it.

Mine works, not to say others don't, I haven't tested them.

This function creates a thumbnail of the specfied size.
If the thumbnail is a different ration it will automatically crop the center of the source image.

It works if the source image is bigger or smaller than the desired "cropped thumbnail."

Here is the code...
<?php
function CroppedThumbnail($imgSrc,$thumbnail_width,$thumbnail_height) { //$imgSrc is a FILE - Returns an image resource.
    //getting the image dimensions 
   
list($width_orig, $height_orig) = getimagesize($imgSrc);  
   
$myImage = imagecreatefromjpeg($imgSrc);
   
$ratio_orig = $width_orig/$height_orig;
   
    if (
$thumbnail_width/$thumbnail_height > $ratio_orig) {
      
$new_height = $thumbnail_width/$ratio_orig;
      
$new_width = $thumbnail_width;
    } else {
      
$new_width = $thumbnail_height*$ratio_orig;
      
$new_height = $thumbnail_height;
    }
   
   
$x_mid = $new_width/2//horizontal middle
   
$y_mid = $new_height/2; //vertical middle
   
   
$process = imagecreatetruecolor(round($new_width), round($new_height));
   
   
imagecopyresampled($process, $myImage, 0, 0, 0, 0, $new_width, $new_height, $width_orig, $height_orig);
   
$thumb = imagecreatetruecolor($thumbnail_width, $thumbnail_height);
   
imagecopyresampled($thumb, $process, 0, 0, ($x_mid-($thumbnail_width/2)), ($y_mid-($thumbnail_height/2)), $thumbnail_width, $thumbnail_height, $thumbnail_width, $thumbnail_height);

   
imagedestroy($process);
   
imagedestroy($myImage);
    return
$thumb;
}

//Create the thumbnail
$newThumb = CroppedThumbnail("MyImageName.jpg",75,100);

// And display the image...
header('Content-type: image/jpeg');
imagejpeg($newThumb);
?>
michael at heymichael dot com 23-Oct-2009 07:08
imagecopyresampled() works amazingly well, but here is something NOT to try with it:

The resize routine I wrote looks for pixel widths, and resizes images based on the notion that if their widths and heights are too big, so are their byte sizes. It worked out well at first.

But when I saw huge byte-size images slipping through beneath my 1000px-wide benchmark, I figured I'd subject the smaller-width images to resizing if their filesize() exceeded 100K.

The idea was that I'd "resize" them keeping their original widths and heights (i.e. in (1) below, $newW = $oldW, $newH = $oldH), and letting the "75" at (2) below reduce the byte size.

DON'T try that. imagecopyresampled() will lock up the server trying to resize an 800px-wide image to a "new" width of 800px. (I caught that on my Windows server before ever putting it on the destination Linux server, so take that with a grain of salt.)

I got around it by making $newW = ($picW * 0.99), etc. You get the byte-size reduction you want without locking up.

(1) imagecopyresampled($image_p, $image, 0, 0, 0, 0, $newW, $newH, $picW, $picH);

(2) imagejpeg($image_p, $theFile, 75);
asgaroth dot belem at gmail dot com 27-Aug-2009 09:42
In case you are having trouble ( like I did ) and getting some kind of noise in the resampled image.

then changing imagecopyresampled() with imagecopyresized()  removes the noise, found that here: http://bugs.php.net/bug.php?id=45030

Do not ask me why. but it works.
asgaroth dot belem at gmail dot com 26-Aug-2009 08:38
About preserving the  transparency when resizing PNGs this was the only thing that worked for me:

<?php imagealphablending($new_watermark, false);
       
$color = imagecolortransparent($new_watermark, imagecolorallocatealpha($new_watermark, 0, 0, 0, 127));
       
imagefill($new_watermark, 0, 0, $color);
       
imagesavealpha($new_watermark, true);
       
imagecopyresampled($new_watermark, $watermark, 0, 0, 0, 0, $new_watermark_width, $new_watermark_height, imagesx($watermark),imagesy($watermark));
?>

Tried without success:

<?php imagealphablending($new_watermark, false);
       
$color = imagecolortransparent($new_watermark, imagecolorallocate($new_watermark, 0, 0, 0));
       
imagefill($new_watermark, 0, 0, $color);
       
imagesavealpha($new_watermark, true);
       
imagecopyresampled($new_watermark, $watermark, 0, 0, 0, 0, $new_watermark_width, $new_watermark_height, imagesx($watermark),imagesy($watermark));
 
?>

hope it helps someone.
z3n666 at gmail dot com 27-Apr-2009 08:19
I was looking around and couldn't find a function that resizes images to any ratio without leaving a blank area, so i wrote this one. It's able to resize images to any size ratio, when the ratio is no match with the original it will crop proportional area on the original and resize it.

<?php

function _ckdir($fn) {
    if (
strpos($fn,"/") !== false) {
       
$p=substr($fn,0,strrpos($fn,"/"));
        if (!
is_dir($p)) {
           
_o("Mkdir: ".$p);
           
mkdir($p,777,true);
        }
    }
}
function
img_resizer($src,$quality,$w,$h,$saveas) {
   
/* v2.5 with auto crop */
   
$r=1;
   
$e=strtolower(substr($src,strrpos($src,".")+1,3));
    if ((
$e == "jpg") || ($e == "peg")) {
       
$OldImage=ImageCreateFromJpeg($src) or $r=0;
    } elseif (
$e == "gif") {
       
$OldImage=ImageCreateFromGif($src) or $r=0;
    } elseif (
$e == "bmp") {
       
$OldImage=ImageCreateFromwbmp($src) or $r=0;
    } elseif (
$e == "png") {
       
$OldImage=ImageCreateFromPng($src) or $r=0;
    } else {
       
_o("Not a Valid Image! (".$e.") -- ".$src);$r=0;
    }
    if (
$r) {
        list(
$width,$height)=getimagesize($src);
       
// check if ratios match
       
$_ratio=array($width/$height,$w/$h);
        if (
$_ratio[0] != $_ratio[1]) { // crop image

            // find the right scale to use
           
$_scale=min((float)($width/$w),(float)($height/$h));

           
// coords to crop
           
$cropX=(float)($width-($_scale*$w));
           
$cropY=(float)($height-($_scale*$h));   
           
           
// cropped image size
           
$cropW=(float)($width-$cropX);
           
$cropH=(float)($height-$cropY);
           
           
$crop=ImageCreateTrueColor($cropW,$cropH);
           
// crop the middle part of the image to fit proportions
           
ImageCopy(
               
$crop,
               
$OldImage,
               
0,
               
0,
                (int)(
$cropX/2),
                (int)(
$cropY/2),
               
$cropW,
               
$cropH
           
);
        }
       
       
// do the thumbnail
       
$NewThumb=ImageCreateTrueColor($w,$h);
        if (isset(
$crop)) { // been cropped
           
ImageCopyResampled(
               
$NewThumb,
               
$crop,
               
0,
               
0,
               
0,
               
0,
               
$w,
               
$h,
               
$cropW,
               
$cropH
           
);
           
ImageDestroy($crop);
        } else {
// ratio match, regular resize
           
ImageCopyResampled(
               
$NewThumb,
               
$OldImage,
               
0,
               
0,
               
0,
               
0,
               
$w,
               
$h,
               
$width,
               
$height
           
);
        }
       
_ckdir($saveas);
       
ImageJpeg($NewThumb,$saveas,$quality);
       
ImageDestroy($NewThumb);
       
ImageDestroy($OldImage);
    }
    return
$r;
}

?>
satanas147 at gmail dot com 02-Apr-2009 05:33
Another add-on to previous php5 class for thumbnail (with a merge of Matt and Zorro's proposals).
This is dedicated to generate thumbnail on the fly for a webpage using the subclass thumbnail.
It saves the generated thumb as myimage_tn, in the same directory.
I'm quite new with php5, so I think this could be optimized, but it seems to work fine.

<?php
// Imaging
class imaging
{
   
// Variables
   
private $img_input;
    private
$img_output;
    private
$img_src;
    private
$format;
    private
$quality = 80;
    private
$x_input;
    private
$y_input;
    private
$x_output;
    private
$y_output;
    private
$resize;

   
// Set image
   
public function set_img($img)
    {
       
// Find format
       
$ext = strtoupper(pathinfo($img, PATHINFO_EXTENSION));
       
// JPEG image
       
if(is_file($img) && ($ext == "JPG" OR $ext == "JPEG"))
        {
           
$this->format = $ext;
           
$this->img_input = ImageCreateFromJPEG($img);
           
$this->img_src = $img;
        }
       
// PNG image
       
elseif(is_file($img) && $ext == "PNG")
        {
           
$this->format = $ext;
           
$this->img_input = ImageCreateFromPNG($img);
           
$this->img_src = $img;
        }
       
// GIF image
       
elseif(is_file($img) && $ext == "GIF")
        {
           
$this->format = $ext;
           
$this->img_input = ImageCreateFromGIF($img);
           
$this->img_src = $img;
        }
       
// Get dimensions
       
$this->x_input = imagesx($this->img_input);
       
$this->y_input = imagesy($this->img_input);
    }

   
// Set maximum image size (pixels)
   
public function set_size($max_x = 100,$max_y = 100)
    {
       
// Resize
       
if($this->x_input > $max_x || $this->y_input > $max_y)
        {
           
$a= $max_x / $max_y;
           
$b= $this->x_input / $this->y_input;
            if (
$a<$b)
            {
               
$this->x_output = $max_x;
               
$this->y_output = ($max_x / $this->x_input) * $this->y_input;
            }
            else
            {
               
$this->y_output = $max_y;
               
$this->x_output = ($max_y / $this->y_input) * $this->x_input;
            }
           
// Ready
           
$this->resize = TRUE;
        }
       
// Don't resize      
       
else { $this->resize = FALSE; }
    }
   
// Set image quality (JPEG only)
   
public function set_quality($quality)
    {
        if(
is_int($quality))
        {
           
$this->quality = $quality;
        }
    }
   
// Save image
   
public function save_img($path)
    {
       
// Resize
       
if($this->resize)
        {
           
$this->img_output = ImageCreateTrueColor($this->x_output, $this->y_output);
           
ImageCopyResampled($this->img_output, $this->img_input, 0, 0, 0, 0, $this->x_output, $this->y_output, $this->x_input, $this->y_input);
        }
       
// Save JPEG
       
if($this->format == "JPG" OR $this->format == "JPEG")
        {
            if(
$this->resize) { imageJPEG($this->img_output, $path, $this->quality); }
            else {
copy($this->img_src, $path); }
        }
       
// Save PNG
       
elseif($this->format == "PNG")
        {
            if(
$this->resize) { imagePNG($this->img_output, $path); }
            else {
copy($this->img_src, $path); }
        }
       
// Save GIF
       
elseif($this->format == "GIF")
        {
            if(
$this->resize) { imageGIF($this->img_output, $path); }
            else {
copy($this->img_src, $path); }
        }
    }
   
// Get width
   
public function get_width()
    {
        return
$this->x_input;
    }
   
// Get height
   
public function get_height()
    {
        return
$this->y_input;
    }
   
// Clear image cache
   
public function clear_cache()
    {
        @
ImageDestroy($this->img_input);
        @
ImageDestroy($this->img_output);
    }
}
class
thumbnail extends imaging {
    private
$image;
    private
$width;
    private
$height;
   
    function
__construct($image,$width,$height) {
parent::set_img($image);
parent::set_quality(80);
parent::set_size($width,$height);
           
$this->thumbnail= pathinfo($image, PATHINFO_DIRNAME).pathinfo($image, PATHINFO_FILENAME).'_tn.'.pathinfo($image, PATHINFO_EXTENSION);
parent::save_img($this->thumbnail);
parent::clear_cache();
        }
    function
__toString() {
            return
$this->thumbnail;
    }
}

********
*
DEMO *
********
$thumb = new thumbnail('./image_dir/sub_dir/myimage.jpg',100,100);
echo
'<img src=\''.$thumb.'\' alt=\'myimage\' title=\'myimage\'/>';

   
?>
zuegs 01-Apr-2009 07:52
Resampling GIFs and retain transparency dosen't work always, as dependent on the resample factor the resulting resampled image has some pattern-noise that prevents "imagegif" to find all the transparent-pixels.
One way to fix this, is to reset all pixels with high alpha to full-transparent:
<?php
// load/create images
$img_src=imagecreatefromgif($g_srcfile);
$img_dst=imagecreatetruecolor($g_iw,$g_ih);
imagealphablending($img_dst, false);

// get and reallocate transparency-color
$transindex = imagecolortransparent($img_src);
if(
$transindex >= 0) {
 
$transcol = imagecolorsforindex($img_src, $transindex);
 
$transindex = imagecolorallocatealpha($img_dst, $transcol['red'], $transcol['green'], $transcol['blue'], 127);
 
imagefill($img_dst, 0, 0, $transindex);
}

// resample
imagecopyresampled($img_dst, $img_src, 0, 0, 0, 0, $g_iw, $g_ih, $g_is[0], $g_is[1]);

// restore transparency
if($transindex >= 0) {
 
imagecolortransparent($img_dst, $transindex);
  for(
$y=0; $y<$g_ih; ++$y)
    for(
$x=0; $x<$g_iw; ++$x)
      if(((
imagecolorat($img_dst, $x, $y)>>24) & 0x7F) >= 100) imagesetpixel($img_dst, $x, $y, $transindex);

// save GIF
imagetruecolortopalette($img_dst, true, 255);
imagesavealpha($img_dst, false);
imagegif($img_dst, $g_dstfile);
imagedestroy($img_dst);
?>
Warren 18-Jan-2009 08:15
This is a function I wrote for making thumbnails -  it will accept a source *image resource* and destination *path*, plus the max dimension and whether the thumbnail should be square.

I chose to accept a resource as the source to make it a bit more efficient to create multiple sizes. For example:

<?php
$src_im
=@imagecreatefromjpeg($pathtofile);
$large = resize($src_im,$destination_large,1024);
@
imagedestroy($src_im);
$medium = resize($large,$destination_medium,500);
@
imagedestroy($large);
$small = resize($medium,$destination_small,125);
@
imagedestroy($medium);
$square = resize($small,$destination_square,75,TRUE);
@
imagedestroy($small);
@
imagedestroy($square);

function
resize($src_im, $dpath, $maxd, $square=false) {
   
$src_width = imagesx($src_im);
   
$src_height = imagesy($src_im);
   
$src_w=$src_width;
   
$src_h=$src_height;
   
$src_x=0;
   
$src_y=0;
    if(
$square){
       
$dst_w = $maxd;
       
$dst_h = $maxd;
        if(
$src_width>$src_height){
           
$src_x = ceil(($src_width-$src_height)/2);
           
$src_w=$src_height;
           
$src_h=$src_height;
        }else{
           
$src_y = ceil(($src_height-$src_width)/2);
           
$src_w=$src_width;
           
$src_h=$src_width;
        }
    }else{
        if(
$src_width>$src_height){
           
$dst_w=$maxd;
           
$dst_h=floor($src_height*($dst_w/$src_width));
        }else{
           
$dst_h=$maxd;
           
$dst_w=floor($src_width*($dst_h/$src_height));
        }
    }
   
$dst_im=@imagecreatetruecolor($dst_w,$dst_h);
    @
imagecopyresampled($dst_im, $src_im, 0, 0, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h);
    @
imagejpeg($dst_im,$dpath);
    return
$dst_im;
}
?>
MBorgPL at gmail dot com 28-Dec-2008 07:53
Another addition to zorroswordsman at gmail dot com's resize class.

The function takes $_FILES['sent_image'] as 1st parameter. The 2nd is complete destination path.

It only moves images.

It returns destination path if succeeded, and false if any error occurred.

<?php
public function move_image($tmp_img, $dest_img)
{
   
//verifies if the uploaded file is an image
   
if (strpos($tmp_img['type'], 'image') !== false)
        {
       
//moves the uploaded file into the destination place
       
if (move_uploaded_file($tmp_img['tmp_name'], $dest_img)) {
            return
$dest_img;
        }
    }       
    return
false;
}
?>
MBorg_PL 28-Dec-2008 12:39
Another tiny ammendment to zorroswordsman at gmail dot com's resize class AND matt at rees-jenkins dot co dot uk addition. The class may resize to different width and height not only same ones:

<?php
// Set maximum image size (pixels)
public function set_size($max_x = 100,$max_y = 100)
{
   
   
// Resize
   
if($this->x_input > $max_x || $this->y_input > $max_y)
    {

       
$a= $max_x / $max_y;
       
$b= $this->x_input / $this->y_input;
       
        if (
$a<$b)
        {

           
$this->x_output = $max_x;
           
$this->y_output = ($max_x / $this->x_input) * $this->y_input;

        }
        else
        {

           
$this->y_output = $max_y;
           
$this->x_output = ($max_y / $this->y_input) * $this->x_input;

        }
       
// Ready
       
       
$this->resize = TRUE;
       
    }
   
   
// Don't resize       
   
else { $this->resize = FALSE; }
   
}
?>

And the use of the class is now:

<?php

##### DEMO #####

// Image
$src = "myimage.jpg";

// Begin
$img = new imaging;
$img->set_img($src);
$img->set_quality(80);

// Small thumbnail
$img->set_size(250,150);
$img->save_img("small_250x150_" . $src);

// Baby thumbnail
$img->set_size(50,250);
$img->save_img("baby_50x250_" . $src);

// Finalize
$img->clear_cache();

?>
matt at rees-jenkins dot co dot uk 14-Oct-2008 12:32
A tiny ammendment to zorroswordsman at gmail dot com's resize class. It was only resizing if both the width AND height where greater than the desired size. This should fix it:

<?php
// Set maximum image size (pixels)
function set_size($size = 100)
{
   
// Resize
   
if($this->x_input > $size || $this->y_input > $size)
    {
       
// Wide
       
if($this->x_input >= $this->y_input)
        {
           
$this->x_output = $size;
           
$this->y_output = ($this->x_output / $this->x_input) * $this->y_input;
        }
       
// Tall
       
else
        {
           
$this->y_output = $size;
           
$this->x_output = ($this->y_output / $this->y_input) * $this->x_input;
        }
       
// Ready
       
$this->resize = TRUE;
    }
   
// Don't resize
   
else { $this->resize = FALSE; }
}
?>
zorroswordsman at gmail dot com 25-Sep-2008 04:46
I've created a PHP5 image resize class, using ImageCopyResampled, that someone might find useful, with support for JPEG, PNG, and GIF formats. It retains the original image's aspect ratio when resizing, and doesn't resize or resample if the original width and height is smaller then the desired resize.

<?php

// Imaging
class imaging
{

   
// Variables
   
private $img_input;
    private
$img_output;
    private
$img_src;
    private
$format;
    private
$quality = 80;
    private
$x_input;
    private
$y_input;
    private
$x_output;
    private
$y_output;
    private
$resize;

   
// Set image
   
public function set_img($img)
    {

       
// Find format
       
$ext = strtoupper(pathinfo($img, PATHINFO_EXTENSION));

       
// JPEG image
       
if(is_file($img) && ($ext == "JPG" OR $ext == "JPEG"))
        {

           
$this->format = $ext;
           
$this->img_input = ImageCreateFromJPEG($img);
           
$this->img_src = $img;
           

        }

       
// PNG image
       
elseif(is_file($img) && $ext == "PNG")
        {

           
$this->format = $ext;
           
$this->img_input = ImageCreateFromPNG($img);
           
$this->img_src = $img;

        }

       
// GIF image
       
elseif(is_file($img) && $ext == "GIF")
        {

           
$this->format = $ext;
           
$this->img_input = ImageCreateFromGIF($img);
           
$this->img_src = $img;

        }

       
// Get dimensions
       
$this->x_input = imagesx($this->img_input);
       
$this->y_input = imagesy($this->img_input);

    }

   
// Set maximum image size (pixels)
   
public function set_size($size = 100)
    {

       
// Resize
       
if($this->x_input > $size && $this->y_input > $size)
        {

           
// Wide
           
if($this->x_input >= $this->y_input)
            {

               
$this->x_output = $size;
               
$this->y_output = ($this->x_output / $this->x_input) * $this->y_input;

            }

           
// Tall
           
else
            {

               
$this->y_output = $size;
               
$this->x_output = ($this->y_output / $this->y_input) * $this->x_input;

            }

           
// Ready
           
$this->resize = TRUE;

        }

       
// Don't resize
       
else { $this->resize = FALSE; }

    }

   
// Set image quality (JPEG only)
   
public function set_quality($quality)
    {

        if(
is_int($quality))
        {

           
$this->quality = $quality;

        }

    }

   
// Save image
   
public function save_img($path)
    {

       
// Resize
       
if($this->resize)
        {

           
$this->img_output = ImageCreateTrueColor($this->x_output, $this->y_output);
           
ImageCopyResampled($this->img_output, $this->img_input, 0, 0, 0, 0, $this->x_output, $this->y_output, $this->x_input, $this->y_input);

        }

       
// Save JPEG
       
if($this->format == "JPG" OR $this->format == "JPEG")
        {

            if(
$this->resize) { imageJPEG($this->img_output, $path, $this->quality); }
            else {
copy($this->img_src, $path); }

        }

       
// Save PNG
       
elseif($this->format == "PNG")
        {

            if(
$this->resize) { imagePNG($this->img_output, $path); }
            else {
copy($this->img_src, $path); }

        }

       
// Save GIF
       
elseif($this->format == "GIF")
        {

            if(
$this->resize) { imageGIF($this->img_output, $path); }
            else {
copy($this->img_src, $path); }

        }

    }

   
// Get width
   
public function get_width()
    {

        return
$this->x_input;

    }

   
// Get height
   
public function get_height()
    {

        return
$this->y_input;

    }

   
// Clear image cache
   
public function clear_cache()
    {

        @
ImageDestroy($this->img_input);
        @
ImageDestroy($this->img_output);

    }

}

##### DEMO #####

// Image
$src = "myimage.jpg";

// Begin
$img = new imaging;
$img->set_img($src);
$img->set_quality(80);

// Small thumbnail
$img->set_size(200);
$img->save_img("small_" . $src);

// Baby thumbnail
$img->set_size(50);
$img->save_img("baby_" . $src);

// Finalize
$img->clear_cache();

?>
crash 12-Aug-2008 03:49
The suggestion of converting a gif to a png to retain transparency was useful. However the steps used to maintain the transparency work for a gif as well, so the conversion step is not necessary. Just do everything the same, and save as a gif anyway. i.e.

<?php
$g_iw is
new image width
$g_ih is
new image height

$img_src
=imagecreatefromgif($g_srcfile);
$img_dst=imagecreatetruecolor($g_iw,$g_ih);

//preserve alpha
imagecolortransparent($img_dst, imagecolorallocate($img_dst, 0, 0, 0));
imagealphablending($img_dst, false);
imagesavealpha($img_dst, true);
imagecopyresampled($img_dst, $img_src, 0, 0, 0, 0, $g_iw, $g_ih, $g_is[0], $g_is[1]);

imagegif($img_dst, $g_dstfile);
imagedestroy($img_dst);
?>
swizec at swizec dot com 17-Jul-2008 11:20
Wrote a function for sanitising user uploaded images. It saves the native image in size roughly 800x600 so it still fits on most screens when opened, makes a desired size thumbnail and turns all images into high quality jpegs for smaller bandwidth use.

Thumbnails are made in a similar way a designer would make them in photoshop, first resize the most troublesome dimension to desired size, then crop the rest out so the image retains proportions and most of it ends up in the thumbnail.

<?php

// $image is $_FILES[ <image name> ]
// $imageId is the id used in a database or wherever for this image
// $thumbWidth and $thumbHeight are desired dimensions for the thumbnail
function processImage( $image, $imageId, $thumbWidth, $thumbHeight )
{
   
$type = $image[ 'type' ];
   
$galleryPath = 'images/collection/';
   
    if (
strpos( $type, 'image/' ) === FALSE )
    {
// not an image
       
return FALSE;
    }
   
$type = str_replace( 'image/', '', $type );
   
$createFunc = 'imagecreatefrom' . $type;
   
   
$im = $createFunc( $image[ 'tmp_name' ] );
   
   
$size = getimagesize( $image[ 'tmp_name' ] );
   
   
$w = $size[ 0 ];
   
$h = $size[ 1 ];
    if (
$w > 800 || $h > 600 )
    {
// we make sure the image isn't too huge
       
if ( $w > 800 )
        {
           
$nw = 800;
           
$nh = ceil( $nw*($h/$w) );
        }elseif(
$h > 600 )
        {
           
$nh = 600;
           
$nw = ceil( $nh*($w/$h) );
        }
       
       
$im2 = imagecreatetruecolor( $nw, $nh );
       
imagecopyresampled( $im2, $im, 0, 0, 0, 0, $nw, $nh, $w, $h );
       
imagedestroy( $im );
       
       
$im = $im2;
       
$w = $nw;
       
$h = $nh;
    }
   
   
// create thumbnail
   
$tw = $thumbWidth;
   
$th = $thumbHeight;
   
$imT = imagecreatetruecolor( $tw, $th );
   
    if (
$tw/$th > $th/$tw )
    {
// wider
       
$tmph = $h*($tw/$w);
       
$temp = imagecreatetruecolor( $tw, $tmph );
       
imagecopyresampled( $temp, $im, 0, 0, 0, 0, $tw, $tmph, $w, $h ); // resize to width
       
imagecopyresampled( $imT, $temp, 0, 0, 0, $tmph/2-$th/2, $tw, $th, $tw, $th ); // crop
       
imagedestroy( $temp );
    }else
    {
// taller
       
$tmpw = $w*($th/$h );
       
$imT = imagecreatetruecolor( $tmpw, $th );
       
imagecopyresampled( $imT, $im, 0, 0, 0, 0, $tmpw, $h, $w, $h ); // resize to height
       
imagecopyresampled( $imT, $temp, 0, 0, $tmpw/2-$tw/2, 0, $tw, $th, $tw, $th ); // crop
       
imagedestroy( $temp );
    }
   
   
// save the image
   
imagejpeg( $im, $galleryPath . $imgid . '.jpg', 100 );
   
imagejpeg( $imT, $galleryPath . $imgid . '_thumb.jpg', 100 );
}

?>
mattura gmail com 19-May-2008 07:53
Here's a little function I wrote to resize images to a maximum dimension - based on what facebook does in the galleries. You put in a source, destination and a maximum dimension in pixels (eg 300), and for example if the image is long and thin, the longest edge will be 300px, yet the image retains proportions. A square image will become 300x300, a 6x4 (landscape) will become 300x200, a 4x6 (portrait) - 200x300 etc.
It works on jpg images, but other formats can easily be added.
<?php
function createThumb($spath, $dpath, $maxd) {
 
$src=@imagecreatefromjpeg($spath);
 if (!
$src) {return false;} else {
 
$srcw=imagesx($src);
 
$srch=imagesy($src);
  if (
$srcw<$srch) {$height=$maxd;$width=floor($srcw*$height/$srch);}
  else {
$width=$maxd;$height=floor($srch*$width/$srcw);}
  if (
$width>$srcw && $height>$srch) {$width=$srcw;$height=$srch;}  //if image is actually smaller than you want, leave small (remove this line to resize anyway)
 
$thumb=imagecreatetruecolor($width, $height);
  if (
$height<100) {imagecopyresized($thumb, $src, 0, 0, 0, 0, $width, $height, imagesx($src), imagesy($src));}
  else {
imagecopyresampled($thumb, $src, 0, 0, 0, 0, $width, $height, imagesx($src), imagesy($src));}
 
imagejpeg($thumb, $dpath);
  return
true;
 }
}
?>
bobbyboyojones at hotmail dot com 18-Mar-2008 08:41
I hated that enlarging an image resulted in giant pixels rather than a smoother look, so I wrote this function.  It takes longer, but gives a much nicer look.

<?php

function imagecopyresampledSMOOTH(&$dst_img, &$src_img, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h, $mult=1.25){
   
// don't use a $mult that's too close to an int or this function won't make much of a difference

   
$tgt_w = round($src_w * $mult);
   
$tgt_h = round($src_h * $mult);
   
   
// using $mult <= 1 will make the current step w/h smaller (or the same), don't allow this, always resize by at least 1 pixel larger
   
if($tgt_w <= $src_w){ $tgt_w += 1; }
    if(
$tgt_h <= $src_h){ $tgt_h += 1; }
   
   
// if the current step w/h is larger than the final height, adjust it back to the final size
    // this check also makes it so that if we are doing a resize to smaller image, it happens in one step (since that's already smooth)
   
if($tgt_w > $dst_w){ $tgt_w = $dst_w; }
    if(
$tgt_h > $dst_h){ $tgt_h = $dst_h; }

   
$tmpImg = imagecreatetruecolor($tgt_w, $tgt_h);

   
imagecopyresampled($tmpImg, $src_img, 0, 0, $src_x, $src_y, $tgt_w, $tgt_h, $src_w, $src_h);
   
imagecopy($dst_img, $tmpImg, $dst_x, $dst_y, 0, 0, $tgt_w, $tgt_h);
   
imagedestroy($tmpImg);

   
// as long as the final w/h has not been reached, reep on resizing
   
if($tgt_w < $dst_w OR $tgt_h < $dst_h){
       
imagecopyresampledSMOOTH($dst_img, $dst_img, $dst_x, $dst_y, $dst_x, $dst_y, $dst_w, $dst_h, $tgt_w, $tgt_h, $mult);
    }
}

?>
arnar at netvistun dot is 16-Mar-2008 07:58
A small thumb script. Lets you specify max height and width. The thumb will always be of a rectangular shape while the image itself retains it's proportions. Very clean.

<?php
// The file
$filename = 'a.jpg';

// Set a maximum height and width
$width = 80;
$height = 80;

$thumbsize = 80;

// Content type
header('Content-type: image/jpeg');

// Get new dimensions
list($width_orig, $height_orig) = getimagesize($filename);

$ratio_orig = $width_orig/$height_orig;

if (
$width/$height > $ratio_orig) {
  
$width = $height*$ratio_orig;
} else {
  
$height = $width/$ratio_orig;
}

// Resample
$image_p = imagecreatetruecolor($thumbsize, $thumbsize);
$image = imagecreatefromjpeg($filename);
imagecopyresampled($image_p, $image, -($width/2) + ($thumbsize/2), -($height/2) + ($thumbsize/2), 0, 0, $width, $height, $width_orig, $height_orig);

// Output
imagejpeg($image_p, null, 100);
?>
rayg at daylongraphics dot com 07-Mar-2008 11:45
Here's a simple function to resample one JPEG imagefile to another while keeping aspect ratio of the source within the destination's dimensions. You can also tune the allowable distortion if you end up making too many thumbnails with thin blank areas around them. Should work when enlarging images too. Function returns true if it worked, false if not.

function resample_picfile($src, $dst, $w, $h)
{
    // If distortion stretching is within the range below,
    // then let image be distorted.
    $lowend = 0.8;
    $highend = 1.25;

    $src_img = imagecreatefromjpeg($src);
    if($src_img)
    {
        $dst_img = ImageCreateTrueColor($w, $h);
        /* if you don't want aspect-preserved images
to have a black bkgnd, fill $dst_img with the color of your choice here.
        */

        if($dst_img)
        {
            $src_w = imageSX($src_img);
            $src_h = imageSY($src_img);

            $scaleX = (float)$w / $src_w;
            $scaleY = (float)$h / $src_h;
            $scale = min($scaleX, $scaleY);

            $dstW = $w;
            $dstH = $h;
            $dstX = $dstY = 0;

            $scaleR = $scaleX / $scaleY;
            if($scaleR < $lowend || $scaleR > $highend)
            {
                $dstW = (int)($scale * $src_w + 0.5);
                $dstH = (int)($scale * $src_h + 0.5);

                // Keep pic centered in frame.
                $dstX = (int)(0.5 * ($w - $dstW));
                $dstY = (int)(0.5 * ($h - $dstH));
            }
           
            imagecopyresampled(
                $dst_img, $src_img, $dstX, $dstY, 0, 0,
                $dstW, $dstH, $src_w, $src_h);
            imagejpeg($dst_img, $dst);
            imagedestroy($dst_img);
        }
        imagedestroy($src_img);
        return file_exists($dst);
    }
    return false;
}
wm at violet dot bg 20-Feb-2008 10:16
This is a fixed version of ImageCopyResampledBicubic posted by liviu.malaescu
The original version wasn't respecting src_x & src_y args

<?php
   
function ImageCopyResampledBicubic(&$dst_image, &$src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h)  {
       
// we should first cut the piece we are interested in from the source
       
$src_img = ImageCreateTrueColor($src_w, $src_h);
       
imagecopy($src_img, $src_image, 0, 0, $src_x, $src_y, $src_w, $src_h);

       
// this one is used as temporary image
       
$dst_img = ImageCreateTrueColor($dst_w, $dst_h);

       
ImagePaletteCopy($dst_img, $src_img);
       
$rX = $src_w / $dst_w;
       
$rY = $src_h / $dst_h;
       
$w = 0;
        for (
$y = 0; $y < $dst_h; $y++)  {
           
$ow = $w; $w = round(($y + 1) * $rY);
           
$t = 0;
            for (
$x = 0; $x < $dst_w; $x++)  {
               
$r = $g = $b = 0; $a = 0;
               
$ot = $t; $t = round(($x + 1) * $rX);
                for (
$u = 0; $u < ($w - $ow); $u++)  {
                    for (
$p = 0; $p < ($t - $ot); $p++)  {
                       
$c = ImageColorsForIndex($src_img, ImageColorAt($src_img, $ot + $p, $ow + $u));
                       
$r += $c['red'];
                       
$g += $c['green'];
                       
$b += $c['blue'];
                       
$a++;
                    }
                }
               
ImageSetPixel($dst_img, $x, $y, ImageColorClosest($dst_img, $r / $a, $g / $a, $b / $a));
            }
        }

       
// apply the temp image over the returned image and use the destination x,y coordinates
       
imagecopy($dst_image, $dst_img, $dst_x, $dst_y, 0, 0, $dst_w, $dst_h);

       
// we should return true since ImageCopyResampled/ImageCopyResized do it
       
return true;
    }
?>
Michael Shepanski 15-Jan-2008 07:09
Here is a function I thought I would share that will resample and copy an image with rounded corners.

<?php
/** ------------------------------------------------------------
 * Copy and resample an image with rounded corners.
 * ----------------------------------------------------------- */
function imageRoundedCopyResampled(&$dstimg, &$srcimg, $dstx, $dsty, $srcx,
                                  
$srcy, $dstw, $dsth, $srcw, $srch, $radius) {
   
# Resize the Source Image
   
$srcResized = imagecreatetruecolor($dstw, $dsth);
   
imagecopyresampled($srcResized, $srcimg, 0, 0, $srcx, $srcy,
                      
$dstw, $dsth, $srcw, $srch);
   
# Copy the Body without corners
   
imagecopy($dstimg, $srcResized, $dstx+$radius, $dsty,
             
$radius, 0, $dstw-($radius*2), $dsth);
   
imagecopy($dstimg, $srcResized, $dstx, $dsty+$radius,
             
0, $radius, $dstw, $dsth-($radius*2));
   
# Create a list of iterations; array(array(X1, X2, CenterX, CenterY), ...)
    # Iterations in order are: Top-Left, Top-Right, Bottom-Left, Bottom-Right
   
$iterations = array(
        array(
0, 0, $radius, $radius),
        array(
$dstw-$radius, 0, $dstw-$radius, $radius),
        array(
0, $dsth-$radius, $radius, $dsth-$radius),
        array(
$dstw-$radius, $dsth-$radius, $dstw-$radius, $dsth-$radius)
    );
   
# Loop through each corner 'iteration'
   
foreach($iterations as $iteration) {
        list(
$x1,$y1,$cx,$cy) = $iteration;
        for (
$y=$y1; $y<=$y1+$radius; $y++) {
            for (
$x=$x1; $x<=$x1+$radius; $x++) {
               
# If length (X,Y)->(CX,CY) is less then radius draw the point
               
$length = sqrt(pow(($cx - $x), 2) + pow(($cy - $y), 2));
                if (
$length < $radius) {
                   
imagecopy($dstimg, $srcResized, $x+$dstx, $y+$dsty,
                             
$x, $y, 1, 1);
                }
            }
        }
    }
}
?>
matt1walsh DESPAMMER gmail dot com 20-Nov-2007 04:15
None of the stuff I've seen for resizing transparent GIFs works consistently and yields a good image. The hack I thought of is silly, but it works okay -- convert GIF to PNG. This worked for me.

$g_iw is new image width
$g_ih is new image height

$img_src=imagecreatefromgif($g_srcfile);
$img_dst=imagecreatetruecolor($g_iw,$g_ih);

//preserve alpha
imagecolortransparent($img_dst, imagecolorallocate($img_dst, 0, 0, 0));
imagealphablending($img_dst, false);
imagesavealpha($img_dst, true);
imagecopyresampled($img_dst, $img_src, 0, 0, 0, 0, $g_iw, $g_ih, $g_is[0], $g_is[1]);

imagepng($img_dst, $g_dstfile);
imagedestroy($img_dst);
Dave McCourt 12-Nov-2007 02:32
This function is taken from lots of web sources so thanks to all for posting. It creates square or landscape thumbnails from .jpgs  from either portait or landscape original images. I decide in advance which way I want the thumbs to display for consistency. I usually sharpen the images as well post-upload, to save on server resources. I can post this code if anyone wants it. I hope this helps someone...

    # create thumbnails from jpgs
    # usage:
    # create_jpgthumb(uploaded file, final file (with path), thumb height, thumb width, jpg quality, scale thumb (true) or fixed size (false);
    function create_jpgthumb($original, $thumbnail, $max_width, $max_height, $quality, $scale = true) {
       
        list ($src_width, $src_height, $type, $w) = getimagesize($original);
       
        if (!$srcImage = @imagecreatefromjpeg($original)) {
            return false;
        }

        # image resizes to natural height and width
        if ($scale == true) {
                       
            if ($src_width > $src_height ) {
                $thumb_width = $max_width;
                $thumb_height = floor($src_height * ($max_width / $src_width));
            } else if ($src_width < $src_height ) {
                $thumb_height = $max_height;
                $thumb_width = floor($src_width * ($max_height / $src_height));
            } else {
                $thumb_width = $max_height;
                $thumb_height = $max_height;
            }

            if (!@$destImage = imagecreatetruecolor($thumb_width, $thumb_height)) {
                return false;
            }
           
            if (!@imagecopyresampled($destImage, $srcImage, 0, 0, 0, 0, $thumb_width, $thumb_height, $src_width, $src_height)) {
                return false;
            }
                       
        # image is fixed to supplied width and height and cropped
        } else if ($scale == false) {
       
            $ratio = $max_width / $max_height;
               
            # thumbnail is landscape
             if ($ratio > 1) {
            
                # uploaded pic is landscape
                if ($src_width > $src_height) {

                    $thumb_width = $max_width;
                    $thumb_height = ceil($max_width * ($src_height / $src_width));
                   
                    if ($thumb_height > $max_width) {
                        $thumb_height = $max_width;
                        $thumb_width = ceil($max_width * ($src_width / $src_height));
                    }

                # uploaded pic is portrait
                } else {
               
                    $thumb_height = $max_width;
                    $thumb_width = ceil($max_width * ($src_height / $src_width));
                   
                    if ($thumb_width > $max_width) {
                        $thumb_width = $max_width;
                        $thumb_height = ceil($max_width * ($src_height / $src_width));
                    }
                   
                    $off_h = ($src_height - $src_width) / 2;
           
                }
   
                if (!@$destImage = imagecreatetruecolor($max_width, $max_height)) {
                    return false;
                }
       
                if (!@imagecopyresampled($destImage, $srcImage, 0, 0, 0, $off_h, $thumb_width, $thumb_height, $src_width, $src_height)) {
                    return false;
                }

            # thumbnail is square
             } else {
            
                if ($src_width > $src_height) {
                    $off_w = ($src_width - $src_height) / 2;
                    $off_h = 0;
                    $src_width = $src_height;
                } else if ($src_height > $src_width) {
                    $off_w = 0;
                    $off_h = ($src_height - $src_width) / 2;
                    $src_height = $src_width;
                } else {
                    $off_w = 0;
                    $off_h = 0;
                }

                if (!@$destImage = imagecreatetruecolor($max_width, $max_height)) {
                    return false;
                }
       
                if (!@imagecopyresampled($destImage, $srcImage, 0, 0, $off_w, $off_h, $max_width, $max_height, $src_width, $src_height)) {
                    return false;
                }

             }
        
                           
        }
       
        @imagedestroy($srcImage);

        if (!@imageantialias($destImage, true)) {
            return false;
        }
       
        if (!@imagejpeg($destImage, $thumbnail, $quality)) {
            return false;
        }
                       
        @imagedestroy($destImage);
       
        return true;
    }
tim dot daldini at gmail dot be 04-Oct-2007 05:57
Tim's function is a whole lot faster, however, the quality setting doesnt seem right since resizing very big images doesnt affect quality of the resulting thumbnails that much on quality 1 for example.

Anyone has figured out how to use a more correct quality setting by comparing image surfaces (for example) basing on Tim's function?

images with a total of 10Megapixels that contain 5Megapixels when resized should use the same quality setting like images that contain 1Megapixels but only 0.5 when resized.

Not hard to understand, but the memoryload would be a lot lower if the function could decide to use a setting of quality 1 automatically when resizing big images to small thumbnails. This would be handy especially when using the function for images of various sizes in the same application.
tim at leethost dot com 08-Sep-2007 06:25
Here's an improved and corrected version of my fastimagecopyresampled script.  Because I typically scale entire images it appears my previous code was not properly tested.  In any case, this new script has been thoroughly tested, cleaned up, and enhanced.  The code is a little tighter and quality values between 0 and 1 will yield a mosaic effect (basically lowering quality below the pervious lowest value of 1).  I would still suggest using a quality of 2 to 4 as that's the primary purpose of this script, which is high quality and fast results.  Don't be afraid of using a quality value of 1.5 for extreme cases where you have a bunch of very large images from digital cameras (like those 10M pixel cameras theses days) and creating thumbnails in batch mode.  Even a quality of 1.5 is a big improvement over imagecopyresized and is ultra-fast.

Anyway, enjoy and I hope this is the bug-free last version.

<?
function fastimagecopyresampled (&$dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h, $quality = 3) {
  // Plug-and-Play fastimagecopyresampled function replaces much slower imagecopyresampled.
  // Just include this function and change all "imagecopyresampled" references to "fastimagecopyresampled".
  // Typically from 30 to 60 times faster when reducing high resolution images down to thumbnail size using the default quality setting.
  // Author: Tim Eckel - Date: 09/07/07 - Version: 1.1 - Project: FreeRingers.net - Freely distributable - These comments must remain.
  //
  // Optional "quality" parameter (defaults is 3). Fractional values are allowed, for example 1.5. Must be greater than zero.
  // Between 0 and 1 = Fast, but mosaic results, closer to 0 increases the mosaic effect.
  // 1 = Up to 350 times faster. Poor results, looks very similar to imagecopyresized.
  // 2 = Up to 95 times faster.  Images appear a little sharp, some prefer this over a quality of 3.
  // 3 = Up to 60 times faster.  Will give high quality smooth results very close to imagecopyresampled, just faster.
  // 4 = Up to 25 times faster.  Almost identical to imagecopyresampled for most images.
  // 5 = No speedup. Just uses imagecopyresampled, no advantage over imagecopyresampled.

  if (empty($src_image) || empty($dst_image) || $quality <= 0) { return false; }
  if ($quality < 5 && (($dst_w * $quality) < $src_w || ($dst_h * $quality) < $src_h)) {
    $temp = imagecreatetruecolor ($dst_w * $quality + 1, $dst_h * $quality + 1);
    imagecopyresized ($temp, $src_image, 0, 0, $src_x, $src_y, $dst_w * $quality + 1, $dst_h * $quality + 1, $src_w, $src_h);
    imagecopyresampled ($dst_image, $temp, $dst_x, $dst_y, 0, 0, $dst_w, $dst_h, $dst_w * $quality, $dst_h * $quality);
    imagedestroy ($temp);
  } else imagecopyresampled ($dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h);
  return true;
}
?>
eblejr AT phrebh DOT com 05-Sep-2007 08:38
Tim's code is fast, but if you're trying to put resampled images anywhere but in the top-left corner, it doesn't work.
Blendermf 05-Jul-2007 05:48
tim, your resampling gives me better results than the gd function. It looks just as good as what my image resizing software does.
kristijan at leftor dot ba 05-Jun-2007 11:09
There is bug in POST from tim at leethost dot com
25-Jan-2007 02:00.

Function work correctly when you making thumb from 0,0 to width/height. But if you want copy resized picture to other coordinates then you must change code in this:

function fastimagecopyresampled (&$dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h, $quality = 3) {
 if (empty($src_image) || empty($dst_image)) { return false; }
 if ($quality <= 1)
 {
   $temp = imagecreatetruecolor ($dst_w + 1, $dst_h + 1);
   imagecopyresized ($temp, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w + 1, $dst_h + 1, $src_w, $src_h);
   imagecopyresized ($dst_image, $temp, 0, 0, 0, 0, $dst_w, $dst_h, $dst_w, $dst_h);
   imagedestroy ($temp);
 }
 elseif ($quality < 5 && (($dst_w * $quality) < $src_w || ($dst_h * $quality) < $src_h))
 {
   $tmp_w = $dst_w * $quality;
   $tmp_h = $dst_h * $quality;
   $temp = imagecreatetruecolor ($tmp_w + 1, $tmp_h + 1);
   imagecopyresized ($temp, $src_image, 0, 0, $src_x, $src_y, $tmp_w + 1, $tmp_h + 1, $src_w, $src_h);
   imagecopyresampled ($dst_image, $temp, $dst_x, $dst_y, 0, 0, $dst_w, $dst_h, $tmp_w, $tmp_h);
   imagedestroy ($temp);
 } else
 {
   imagecopyresampled ($dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h);
 }
 return true;
}
rich at corephp dot co dot uk 21-May-2007 12:05
Be wary of this function when resizing images to make them *larger* than the original due to the memory consumption rate. For example a 200KB JPEG file (1024x768) will take up 4MB of memory when loaded, but when resampled to twice the the size the memory use jumps to 20.1MB. imagecopyresized does the same. Allow approx. 5 bytes per *pixel* for memory allowance when dealing with true colour images.
tim at leethost dot com 25-Jan-2007 11:00
Here's a simple plug-and-play replacement to imagecopyresampled that will deliver results that are almost identical except MUCH faster (very typically 30 times faster).  I've been using this function for a few years but figured everyone could benefit from it.

For example, a 10 megapixel camera image (3872x2592 resolution) converted to thumbnail size using the default quality is 60 times faster than using imagecopyresampled (only 0.15 seconds from 8.9 seconds) and the image quality is almost identical.  There's also an optional "quality" parameter that allows you to select the quality you want (1 is lowest quality but fastest, 5 is highest quality but slowest, 3 is default).  All existing imagecopyresampled parameters fully work so it's truly plug-and-play.  It also automatically decides if it would be better to just use imagecopyresampled depending on source and destination image sizes.

My image analysis shows imagecopyresized renders on average 2.4% of pixels significantly different than imagecopyresampled.  These significantly different pixels give imagecopyresized the jagged, blocky, aliasing look.  Using fastimagecopyresampled with a quality of 2, the significantly different pixel rate is reduced to 0.8%.  With a quality of 3 (the default) it's reduced to 0.5% and at a quality of 4 it's reduced to only 0.03% but is still very typically 10-15 times faster for thumbnail creation.

Enjoy!

<?
function fastimagecopyresampled (&$dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h, $quality = 3) {
  // Plug-and-Play fastimagecopyresampled function replaces much slower imagecopyresampled.
  // Just include this function and change all "imagecopyresampled" references to "fastimagecopyresampled".
  // Typically from 30 to 60 times faster when reducing high resolution images down to thumbnail size using the default quality setting.
  // Author: Tim Eckel - Date: 12/17/04 - Project: FreeRingers.net - Freely distributable.
  //
  // Optional "quality" parameter (defaults is 3).  Fractional values are allowed, for example 1.5.
  // 1 = Up to 600 times faster.  Poor results, just uses imagecopyresized but removes black edges.
  // 2 = Up to 95 times faster.  Images may appear too sharp, some people may prefer it.
  // 3 = Up to 60 times faster.  Will give high quality smooth results very close to imagecopyresampled.
  // 4 = Up to 25 times faster.  Almost identical to imagecopyresampled for most images.
  // 5 = No speedup.  Just uses imagecopyresampled, highest quality but no advantage over imagecopyresampled.

  if (empty($src_image) || empty($dst_image)) { return false; }
  if ($quality <= 1) {
    $temp = imagecreatetruecolor ($dst_w + 1, $dst_h + 1);
    imagecopyresized ($temp, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w + 1, $dst_h + 1, $src_w, $src_h);
    imagecopyresized ($dst_image, $temp, 0, 0, 0, 0, $dst_w, $dst_h, $dst_w, $dst_h);
    imagedestroy ($temp);
  } elseif ($quality < 5 && (($dst_w * $quality) < $src_w || ($dst_h * $quality) < $src_h)) {
    $tmp_w = $dst_w * $quality;
    $tmp_h = $dst_h * $quality;
    $temp = imagecreatetruecolor ($tmp_w + 1, $tmp_h + 1);
    imagecopyresized ($temp, $src_image, $dst_x * $quality, $dst_y * $quality, $src_x, $src_y, $tmp_w + 1, $tmp_h + 1, $src_w, $src_h);
    imagecopyresampled ($dst_image, $temp, 0, 0, 0, 0, $dst_w, $dst_h, $tmp_w, $tmp_h);
    imagedestroy ($temp);
  } else {
    imagecopyresampled ($dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h);
  }
  return true;
}
?>
mr bitmap 17-Nov-2006 04:18
For all those that are using imagecreatefromwbmp() for.BMP files, I believe you are wrong.

imagecreatefromwbmp() is for WBMP image files used for WAP devices not windows BMP images.

I don't think PHP has any built in Windows BMP functions.

There are many examples here that make this mistake.

See the documentation for imagecreatefromwbmp()
caio at daisuki dot com dot br 14-Jul-2006 11:51
Ok guys, the ultimate image merging tool, enjoy:

  function watermark($sourcefile, $watermarkfiles, $destination, $quality=90) {
  /*
 
    $sourcefile = Filename of the picture to be watermarked.
    $watermarkfile = files to add. Each is: array ( 'filename' => filename , 'position' => position to show(array), 'resample' => new dimension(array) )
       You can omit any except filename
    $destination = jpg or png file to output (jpg if source is jpg, png if source is png). Send blank to direct output 
    Sample:
 
    $batch = array ( array ( 'filename' => "watermark.png",
                             'position' => array(100,0),
                           ),
                    array ( 'filename' => "brilho.png",
                            'position' => array(200,200),
                            'resample' => array(30,30)
                           )
                   );
    watermark("picture.jpg", $batch, "", 90); <--  will add both images in bath on top of picture, preserving transparency
 
  */
 
  $ih = getimagesize($sourcefile);
  $ispng = $ih[2] == 3;
  if ($ispng)
    $sourcefile_id = imagecreatefrompng($sourcefile);
  else
    $sourcefile_id = imagecreatefromjpeg($sourcefile);
  
  $sourcefile_width=imageSX($sourcefile_id);
  $sourcefile_height=imageSY($sourcefile_id);  
 
  foreach ($watermarkfiles as $x => $watermarkfile) {
    $watermarkfile_id = imagecreatefrompng($watermarkfile['filename']);
    imageAlphaBlending($watermarkfile_id, false);
    imageSaveAlpha($watermarkfile_id, true);    
    $watermarkfile_width=imageSX($watermarkfile_id);
    $watermarkfile_height=imageSY($watermarkfile_id);
   
    // resample?
    if (isset($watermarkfile['resample'])) {
      $im_dest = imagecreatetruecolor ($watermarkfile['resample'][0], $watermarkfile['resample'][1]);
      imagealphablending($im_dest, false);
      imagecopyresampled($im_dest, $watermarkfile_id, 0, 0, 0, 0, $watermarkfile['resample'][0], $watermarkfile['resample'][1], $watermarkfile_width, $watermarkfile_height);
      imagesavealpha($im_dest, true);
      imagedestroy($watermarkfile_id);
      $watermarkfile_id = $im_dest;
      $watermarkfile_width = $watermarkfile['resample'][0];
      $watermarkfile_height = $watermarkfile['resample'][1];
    }
   
    // position ? if none given, centered
    if (isset($watermarkfile['position']))
      list($dest_x,$dest_y) = $watermarkfile['position'];
    else {
      $dest_x = ( $sourcefile_width / 2 ) - ( $watermarkfile_width / 2 ); // centered
      $dest_y = ( $sourcefile_height / 2 ) - ( $watermarkfile_height / 2 ); // centered
    }
   
    imagecopy($sourcefile_id, $watermarkfile_id, $dest_x, $dest_y, 0, 0, $watermarkfile_width, $watermarkfile_height);
    imagedestroy($watermarkfile_id);
  }
  if ($ispng)
    imagepng($sourcefile_id,$destination);
  else
    imagejpeg($sourcefile_id,$destination,$quality);
  imagedestroy($sourcefile_id);
}
Tyron Madlener (tyron.at) 11-May-2006 10:43
Creating a thumbnail (120x90 pixel) of a big image (3000x2000 pixel) took me about 5 seconds with imagecopyresampled()

Thats pretty much, so I tested a little how I could improve the speed. I found that imagecopyresized is way faster but results in poor quality.
So I combined both - I first reduce the big image via imagecopyresized to 1024x768 pixel and then create the small thumbnail via imagecopyresampled. The resulting quality is almost the same. In my tests, resizing took only about 2.2 seconds now - twice as fast :)

I also tried using that bicubic image resizing function in some earlier post here, but it was only faster when the thumbnails were smaller than 120x90 and the quality was not very good.

Here's the code if you wanna (I guess there are still a few possibilites to do some more optimiztions tough):

<?php
function CreateThumb($file,$maxwdt,$maxhgt, $dest) {
    list(
$owdt,$ohgt,$otype)=@getimagesize($file);

  switch(
$otype) {
    case
1$newimg=imagecreatefromgif($file); break;
    case
2$newimg=imagecreatefromjpeg($file); break;
    case
3$newimg=imagecreatefrompng($file); break;
    default: echo
"Unkown filetype (file $file, typ $otype)"; return;
  }
   
  if(
$newimg) {
    if(
$owdt>1500 || $ohgt>1200)
            list(
$owdt, $ohgt) = Resample($newimg, $owdt, $ohgt, 1024,768,0);
           
   
Resample($newimg, $owdt, $ohgt, $maxwdt, $maxhgt);
       
        if(!
$dest) return $newimg;
       
        if(!
is_dir(dirname($dest)))
           
mkdir(dirname($dest));
   
    switch(
$otype) {
      case
1: imagegif($newimg,dest); break;    
      case
2: imagejpeg($newimg,$dest,90); break;
      case
3: imagepng($newimg,$dest);  break;
    }
       
       
imagedestroy($newimg);
   
   
chmod($dest,0644);
  }
}

function
Resample(&$img, $owdt, $ohgt, $maxwdt, $maxhgt, $quality=1) {
  if(!
$maxwdt) $divwdt=0;
   else
$divwdt=Max(1,$owdt/$maxwdt);
  
  if(!
$maxhgt) $divhgt=0;
   else
$divhgt=Max(1,$ohgt/$maxhgt);
   
  if(
$divwdt>=$divhgt) {
   
$newwdt=$maxwdt;
   
$newhgt=round($ohgt/$divwdt);
  } else {
   
$newhgt=$maxhgt;
   
$newwdt=round($owdt/$divhgt);
  }
   
   
$tn=imagecreatetruecolor($newwdt,$newhgt);
    if(
$quality)
       
imagecopyresampled($tn,$img,0,0,0,0,$newwdt,$newhgt,$owdt,$ohgt);       
    else
       
imagecopyresized($tn,$img,0,0,0,0,$newwdt,$newhgt,$owdt,$ohgt);

   
imagedestroy($img);
   
   
$img = $tn;
   
    return array(
$newwdt, $newhgt);
}
?>
dmitry at dest dot by 07-Mar-2006 03:03
Simple script on change of width and automatic creation of height, and also creation of the signature in the right we string to a corner. (Only for Jpg)

function easyResize($img_sourse, $save_to, $quality, $width, $str) {
$size = GetImageSize($img_sourse);
    $im_in = ImageCreateFromJPEG($img_sourse);
   
    $new_height = ($width * $size[1]) / $size[0]; // Generate new height for image
    $im_out = imagecreatetruecolor($width, $new_height);
   
    ImageCopyResampled($im_out, $im_in, 0, 0, 0, 0, $width, $new_height, $size[0], $size[1]);
       
    #Find X & Y for note
    $X_var = ImageSX($im_out);
    $X_var = $X_var - 130;
    $Y_var = ImageSY($im_out);
    $Y_var = $Y_var - 25;

    #Color
    $white = ImageColorAllocate($im_out, 0, 0, 0);
   
    #Add note(simple: site address)
    ImageString($im_out,2,$X_var,$Y_var,$str,$white);

    ImageJPEG($im_out, $save_to, $quality); // Create image
    ImageDestroy($im_in);
    ImageDestroy($im_out);
}

// $str -  Inscription on the image;
areddan at silverarm dot ie 29-Jan-2006 03:30
$file =$_FILES[userfile];
//name of the input form file upload element is userfile

//$to_file is a full path including filename
//to where you want the thumnail to be copied to .
//example /usr/www/users/www/images/thumbs/thumb1.jpg

copy($file[tmp_name],$to_file) or die("The file $file[tmp_name] you are trying to upload couldn't be copied to $to_file");

//Extra stuff to put into the output to allow for jpeg / png or gif

//replace line: imagegif($thumb2, $fileout); //write to file with the following

switch($format)
       {
           case 'image/jpeg':
           imagejpeg($thumb2, $fileout,90); //write to file
           break;
           case 'image/gif';
           imagegif($thumb2, $fileout); //write to file
           break;
           case 'image/png':
           imagepng($thumb2, $fileout); //write to file
           break;
       }
areddan at silverarm dot ie 27-Jan-2006 09:40
<?php
// The file
$filein = ''; // File in
$fileout = 'ttt.gif'; // Fileout - optional

$imagethumbsize_w = 100; // thumbnail size (area cropped in middle of image)
$imagethumbsize_h = 75; // thumbnail size (area cropped in middle of image)
resize_then_crop( $filein,$fileout,$imagethumbsize_w,
$imagethumbsize_h,/*rgb*/"255","255","255");

//Author Alan Reddan Silverarm Solutions
//Date 27/01/2005
//Function that works well with images.
//It takes the image and reduces its size to best fit. i.e If you have an image
//that is 200 X 100 and you want a thumbnail of 75 X 50,
//it first resizes the image to 100 X 50
//and then takes out a portion 75 X 50 from then center of the input image.
//So loads of image information is retained.
//The corollary also holds if your input image is 100 X 200
//it first resizes image to 75 X 150 and then takes out a
//portion 75 X 75 from the centre
// The advantage here is that function decides on whether
//resize is by width or height itself.
//it also decides whether to use the height or the width as the base start point
//in the case that athumbnail is rectangular

function resize_then_crop( $filein,$fileout,
$imagethumbsize_w,$imagethumbsize_h,$red,$green,$blue)
{

// Get new dimensions
list($width, $height) = getimagesize($filein);
$new_width = $width * $percent;
$new_height = $height * $percent;

   if(
preg_match("/.jpg/i", "$filein"))
   {
      
$format = 'image/jpeg';
   }
   if (
preg_match("/.gif/i", "$filein"))
   {
      
$format = 'image/gif';
   }
   if(
preg_match("/.png/i", "$filein"))
   {
      
$format = 'image/png';
   }
  
       switch(
$format)
       {
           case
'image/jpeg':
          
$image = imagecreatefromjpeg($filein);
           break;
           case
'image/gif';
          
$image = imagecreatefromgif($filein);
           break;
           case
'image/png':
          
$image = imagecreatefrompng($filein);
           break;
       }

$width = $imagethumbsize_w ;
$height = $imagethumbsize_h ;
list(
$width_orig, $height_orig) = getimagesize($filein);

if (
$width_orig < $height_orig) {
 
$height = ($imagethumbsize_w / $width_orig) * $height_orig;
} else {
   
$width = ($imagethumbsize_h / $height_orig) * $width_orig;
}

if (
$width < $imagethumbsize_w)
//if the width is smaller than supplied thumbnail size
{
$width = $imagethumbsize_w;
$height = ($imagethumbsize_w/ $width_orig) * $height_orig;;
}

if (
$height < $imagethumbsize_h)
//if the height is smaller than supplied thumbnail size
{
$height = $imagethumbsize_h;
$width = ($imagethumbsize_h / $height_orig) * $width_orig;
}

$thumb = imagecreatetruecolor($width , $height); 
$bgcolor = imagecolorallocate($thumb, $red, $green, $blue);  
ImageFilledRectangle($thumb, 0, 0, $width, $height, $bgcolor);
imagealphablending($thumb, true);

imagecopyresampled($thumb, $image, 0, 0, 0, 0,
$width, $height, $width_orig, $height_orig);
$thumb2 = imagecreatetruecolor($imagethumbsize_w , $imagethumbsize_h);
// true color for best quality
$bgcolor = imagecolorallocate($thumb2, $red, $green, $blue);  
ImageFilledRectangle($thumb2, 0, 0,
$imagethumbsize_w , $imagethumbsize_h , $white);
imagealphablending($thumb2, true);

$w1 =($width/2) - ($imagethumbsize_w/2);
$h1 = ($height/2) - ($imagethumbsize_h/2);

imagecopyresampled($thumb2, $thumb, 0,0, $w1, $h1,
$imagethumbsize_w , $imagethumbsize_h ,$imagethumbsize_w, $imagethumbsize_h);

// Output
//header('Content-type: image/gif');
//imagegif($thumb); //output to browser first image when testing

if ($fileout !="")imagegif($thumb2, $fileout); //write to file
header('Content-type: image/gif');
imagegif($thumb2); //output to browser
}
?>
George_A 07-Nov-2005 11:49
For the best image quality...
How to get new proportional size of the image if the desible size of source image is approximatly equal to needed size. If needed size differs from source size on less than the user factor then transformation isn`t apply.

/**********************************************/
function imageCopyResize($image, $xSize, $ySize, $needed_user_factor, $new_image_path = "")
{
 //example: neded_user_factor = 0.2
 if($xSize == 0 || $ySize == 0)
    return array("At the leat one pair of size is 0",0,0);

 $size = getImageSize($image);
 $width = $size[0];
 $height = $size[1];
 $x_ratio = $xSize / $size[0];
 $y_ratio = $ySize / $size[1];
 if($x_ratio > $y_ratio)    $res_ratio = $y_ratio;
 else $res_ratio = $x_ratio;
 if(abs($res_ratio - 1) > $needed_user_factor)
    {
     $width = ceil($width * $res_ratio);
     $height = ceil($height * $res_ratio);
    }
 $fileinfo = pathinfo($image);
 $file_type = strtolower($fileinfo["extension"]);
 if($file_type == "jpg" || $file_type == "jpeg")
    $src = ImageCreateFromJpeg($image);
 else if($file_type == "gif")
    $src = ImageCreateFromGif($image);
 else if($file_type == "png")
    $src = ImageCreateFromPNG($image);
 else if($file_type == "bmp")   
    $src = ImageCreateFromBmp($image);    //Thanks Previous Coder
 else
   return array("Unknown image format: ".$file_type, 0, 0);  
 $output_path = ($new_image_path == "")?$image:$new_image_path;
 $dst = ImageCreateTrueColor($width, $height);
 ImageCopyResized($dst, $src, 0,0,0,0,$width, $height, $size[0], $size[1]);
 if($file_type == "jpg" || $file_type == "jpeg")
    ImageJpeg($dst, $output_path, 100);
 else if($file_type == "gif" || $file_type == "bmp")
     ImageGif($dst, $output_path);
 else if($file_type == "png")
    ImagePNG($dst, $output_path);

 ImageDestroy($src);
 ImageDestroy($dst);
 return array("", $width, $height);
}
/**********************************************/
erik at phpcastle dot com 05-Nov-2005 11:21
I've changed the script from info at lontronics dot nl a little bit so the thumbnail is not cutted off when this is not necessary.

<?php
// Resize function

// $pictype is optional. When empty the image will not be cutted off
function resize($filename, $dest, $width, $height, $pictype = "")
{
 
$format = strtolower(substr(strrchr($filename,"."),1));
  switch(
$format)
  {
    case
'gif' :
   
$type ="gif";
   
$img = imagecreatefromgif($filename);
    break;
    case
'png' :
   
$type ="png";
   
$img = imagecreatefrompng($filename);
    break;
    case
'jpg' :
   
$type ="jpg";
   
$img = imagecreatefromjpeg($filename);
    break;
    case
'jpeg' :
   
$type ="jpg";
   
$img = imagecreatefromjpeg($filename);
    break;
    default :
    die (
"ERROR; UNSUPPORTED IMAGE TYPE");
    break;
  }

  list(
$org_width, $org_height) = getimagesize($filename);
 
$xoffset = 0;
 
$yoffset = 0;
  if (
$pictype == "thumb") // To minimize destortion
 
{
    if (
$org_width / $width > $org_height/ $height)
    {
     
$xtmp = $org_width;
     
$xratio = 1-((($org_width/$org_height)-($width/$height))/2);
     
$org_width = $org_width * $xratio;
     
$xoffset = ($xtmp - $org_width)/2;
    }
    elseif (
$org_height/ $height > $org_width / $width)
    {
     
$ytmp = $org_height;
     
$yratio = 1-((($width/$height)-($org_width/$org_height))/2);
     
$org_height = $org_height * $yratio;
     
$yoffset = ($ytmp - $org_height)/2;
    }
 
//Added this else part -------------
 
} else {   
     
$xtmp = $org_width/$width;
     
$new_width = $width;
     
$new_height = $org_height/$xtmp;
      if (
$new_height > $height){
       
$ytmp = $org_height/$height;
       
$new_height = $height;
       
$new_width = $org_width/$ytmp;
      }
     
$width = round($new_width);
     
$height = round($new_height);
  }
 

 
$img_n=imagecreatetruecolor ($width, $height);
 
imagecopyresampled($img_n, $img, 0, 0, $xoffset, $yoffset, $width, $height, $org_width, $org_height);

  if(
$type=="gif")
  {
   
imagegif($img_n, $dest);
  }
  elseif(
$type=="jpg")
  {
   
imagejpeg($img_n, $dest);
  }
  elseif(
$type=="png")
  {
   
imagepng($img_n, $dest);
  }
  elseif(
$type=="bmp")
  {
   
imagewbmp($img_n, $dest);
  }
  Return
true;
}
?>
info at lontronics dot nl 28-Oct-2005 12:08
For an internet photoalbum I was looking for a script which I could simply drop in a directory with images and which would do the rest.
Therefor I am using the following resize script now. I have made the little thumb-part because I want to have all the same size thumbnails, but with as less as possible distortion. Therefor, images with other dimensions are resized, but also cut off a little.

Als $pictype = thumb, the extra dimension calculations are used
$width and $height are the new dimensions of $filename, the image
$dest is the directory where the new image must be copied in.

The script:

// Resize function
function resize($filename, $dest, $width, $height, $pictype)
{
    $format = strtolower(substr(strrchr($filename,"."),1));
    switch($format)
    {
        case 'gif' :
            $type ="gif";
            $img = imagecreatefromgif($filename);
            break;
        case 'png' :
            $type ="png";
            $img = imagecreatefrompng($filename);
            break;
        case 'jpg' :
            $type ="jpg";
            $img = imagecreatefromjpeg($filename);
            break;
        case 'jpeg' :
            $type ="jpg";
            $img = imagecreatefromjpeg($filename);
            break;
        default :
            die ("ERROR; UNSUPPORTED IMAGE TYPE");
            break;
    }
   
    list($org_width, $org_height) = getimagesize($filename);
    $xoffset = 0;
    $yoffset = 0;
    if ($pictype == "thumb") // To minimize destortion
    {
        if ($org_width / $width > $org_height/ $height)
        {
            $xtmp = $org_width;
            $xratio = 1-((($org_width/$org_height)-($width/$height))/2);
            $org_width = $org_width * $xratio;
            $xoffset = ($xtmp - $org_width)/2;
        }
        elseif ($org_height/ $height > $org_width / $width)
        {
            $ytmp = $org_height;
            $yratio = 1-((($width/$height)-($org_width/$org_height))/2);
            $org_height = $org_height * $yratio;
            $yoffset = ($ytmp - $org_height)/2;
        }
    }

    $img_n=imagecreatetruecolor ($width, $height);   
    imagecopyresampled($img_n, $img, 0, 0, $xoffset, $yoffset, $width, $height, $org_width, $org_height);

    if($type=="gif")
    {
        imagegif($img_n, $dest);
    }
    elseif($type=="jpg")
    {
        imagejpeg($img_n, $dest);
    }
    elseif($type=="png")
    {
        imagepng($img_n, $dest);
    }
    elseif($type=="bmp")
    {
        imagewbmp($img_n, $dest);
    }
    Return true;
}
Nicolas dot Grasset at notup2u dot net 20-Oct-2005 11:33
If you are looking for a function that can resample your photos to a given size, no matter its original size and/or ratio, here it is. And to make more fun (beacause life has to be fun), you can even chose a border size for the picture!

$position can either be topleft, topright, bottomleft, bottomright or center.

<?php

function imagecopyresampledselection($filename, $desired_width, $desired_height, $bordersize, $position)
{   
   
// Get new dimensions
   
list($width, $height) = getimagesize($filename);
    if(
$desired_width/$desired_height > $width/$height):
       
$new_width = $desired_width;
       
$new_height = $height * ($desired_width / $width);
    else:
       
$new_width = $width * ($desired_height / $height);
       
$new_height = $desired_height;
    endif;
   
   
// Resize
   
$image_p = imagecreatetruecolor($new_width, $new_height);
   
$image_f = imagecreatetruecolor($desired_width, $desired_height);
   
$image = imagecreatefromjpeg($filename);
   
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
   
   
// Adjust position
   
switch($position)
    {
        case(
"topleft"):
           
$x = $bordersize;
           
$y = $bordersize;
            break;
           
        case(
"topright"):
           
$x = $new_width - $desired_width + $bordersize;
           
$y = $bordersize;
            break;
       
        case(
"bottomleft"):
           
$x = $bordersize;
           
$y = $new_height - $desired_height + $bordersize;
            break;
       
        case(
"bottomright"):
           
$x = $new_width - $desired_width + $bordersize;
           
$y = $new_height - $desired_height + $bordersize;
            break;
       
        case(
"center"):
           
$x = ($new_width - $desired_width) / 2 + $bordersize;
           
$y = ($new_height - $desired_height) / 2 + $bordersize;
            break;
    }
   
   
// Resample with 1px border
   
imagecopyresampled($image_f, $image_p, $bordersize, $bordersize, $x, $y,     $desired_width    - 2 * $bordersize,
                                                                               
$desired_height    - 2 * $bordersize,
                                                                               
$desired_width    - 2 * $bordersize,
                                                                               
$desired_height    - 2 * $bordersize);
   
    return
$image_f;
}

$image_f = imagecopyresampledselection('test.jpg', 571, 319, 1, "center");
header('Content-type: image/jpeg');
imagejpeg($image_f, null, 100);

?>

To see a result, just browse http://www.notup2u.net/v8

Nicolas Grasset
12-Aug-2005 02:19
Here is my own custom utility which I call "Thumbnailer" (I know it is cheesy).
It's rather short, and it will take JPEG (you can change that easily), and
format it to a specified output width and height as a PNG
(or whatever else you choose):
<?php
//Dimensions
$outWidth=100; $outHeight=75;
//Do it
$imgSrc=imagecreatefromjpeg("[source]");
$srcWidth=imagesx($imgSrc);
$srcHeight=imagesy($imgSrc);
//Make thumbnails
$imgOut=imagecreatetruecolor($outWidth,$outHeight);
imagerectangle($imgOut,0,0,$outWidth,$outHeight,
 
imagecolorallocate($imgOut,0,0,0));
//Copy them proportionatly
$dx=0; $dy=0; $dw=$outWidth; $dh=$outHeight;
if (
$outWidth*$srcHeight!=$outHeight*$srcWidth) { //Non-proportional, cut-off
 //Which dimensions is larger
 
if ($srcWidth>$srcHeight) { //Empty space on top and bottom
 
$dw=$outWidth;
 
$dh=($dw*$srcHeight)/$srcWidth;
 
$dy=($outHeight-$dh)/2;
 }
 else {
//Empty space on left and right
 
$dh=$outHeight;
 
$dw=($dh*$srcWidth)/$srcHeight;
 
$dx=($outWidth-$dw)/2;
 }
}
imagecopyresampled($imgOut,$imgSrc,$dx,$dy,0,0,
 
$dw,$dh,$srcWidth,$srcHeight); //imagecopyresized for lower quality
//Create the thumbnail and destroy everything else
imagepng($imgOut,"[out]");
echo
"Image created successfully: $outWidth x $outHeight, ".round(filesize("[source]")/1024)." KB<br>";
imagedestroy($imgSrc);
imagedestroy($imgOut);
?>
I just use this as a loop to create thumbnails for a series of ordered images.
phpman at paodj dot net 20-Jul-2005 12:27
<?php

function img_resize($path,$w=0,$h=0,$quality=100,$save=''){

 
$image_data=@getimagesize($path);

 
$image_type=$image_data[2];
 
$gd_ext=array('','jpg','gif');
  if(
$image_type!=1&&$image_type!=2) return false;
  if(
$save=='') header('Content-type: '.$image_data['mime']); else $save=eregi_replace('%ext',$gd_ext[$image_type],$save);

  if(
$w!=0){
   
$rapporto=$image_data[0]/$w;
    if(
$h!=0){
      if(
$image_data[1]/$rapporto>$h) $rapporto=$image_data[1]/$h;
    }
  }elseif(
$h!=0){
   
$tmp_h=$image_data[1]/$h;
  }else{
    return
false;
  }

 
$thumb_w=$image_data[0]/$rapporto;
 
$thumb_h=$image_data[1]/$rapporto;

  if(
$image_type==1) $img_src=@imagecreatefromgif($path);
  elseif(
$image_type==2) $img_src=@imagecreatefromjpeg($path);

 
$img_thumb=@imagecreatetruecolor($thumb_w,$thumb_h);
 
$result=@imagecopyresampled($img_thumb,$img_src,
0,0,0,0,$thumb_w,$thumb_h,$image_data[0],$image_data[1]);
  if(!
$img_src||!$img_thumb||!$result) return false;

  if(
$image_type==1) $result=@imagegif($img_thumb,$save);
  elseif(
$image_type==2) $result=@imagejpeg($img_thumb,$save,$quality);

  return
$result;
}

?>

This script resize images. It can also make thumbs. It use the resample of images for hight quality result.

It can show the result or save it (if $save isn't null).
It respect the width and/or the height of image.
It can replace the destination file extestion dinamically (filename.%ext)
Support gif & jpg.

Return false if something goes wrong.
05-Jul-2005 02:46
It should be noted that the imagecopyresampled() function is much more blurry than Photoshop CS's default bicubic funtion. And looks similar to a blury version of Photoshop's bilinear function. The documentation fails to note which algorithm is used in resampling.
Pie pie 26-May-2005 02:21
Confirming on what fluffle said, and to say his code will also crop and resize an image what is smaller than 100x100 pixels if you want. This is important because it means your images no matter how you decide to rezise them, will maintain their aspect ratios and with a minimum amount of image loss.

    //Get file type
    $mime = $orig_image_mimetype;
    $type = substr($mime, strpos($mime,'/')+1);
    switch($type) {
        case 'jpeg':
        case 'pjpeg':
            $big = imagecreatefromjpeg($file);
            break;
        case 'png':
        case 'x-png':
            $big = imagecreatefrompng($file);
             break;
        case 'gif':
            $big = imagecreatefromgif($file);
            break;
        default:
            return FALSE;
            break;
    }

The above code is what I use to support multiple file type resizing. I then use the same thing again when it's time to output the image using $result = imagejpeg($thumb,'',80), imagepng($thumb), and imagegif($thumb).
fluffle <at> gmail <dot> com 21-May-2005 10:35
Just to clarify that src_w and src_h do not necessarily need to be the source image width and height, as they specify the size of the rectangle cropped from the source picture, with its top left corner situated at (src_x, src_y).

For example, the code below crops a jpeg image to be square, with the square situated in the centre of the original image, and then resizes it to a 100x100 thumbnail.

list($ow, $oh) = getimagesize($image_filename);
$big = imagecreatefromjpeg($image_filename);
$thumb = imagecreatetruecolor(100,100);
if ($ow > $oh) {
    $off_w = ($ow-$oh)/2;
    $off_h = 0;
    $ow = $oh;
} elseif ($oh > $ow) {
    $off_w = 0;
    $off_h = ($oh-$ow)/2;
    $oh = $ow;
} else {
    $off_w = 0;
    $off_h = 0;
}
imagecopyresampled($thumb, $big, 0, 0, $off_w, $off_h, 100, 100, $ow, $oh);
carnivorous_winds_fr AT yahoo DOT fr 19-May-2005 07:47
I tried this code from a previous post.

<?
...
         $t_im = imageCreateTrueColor($t_wd,$t_ht);
         imageAntiAlias($t_im,true);
         imagealphablending($t_im, false);
         imagesavealpha($t_im,true);
         $transparent = imagecolorallocatealpha($t_im, 255, 255, 255, 0);
         for($x=0;$x<$t_wd;$x++) {
           for($y=0;$y<$t_ht;$y++) {
             imageSetPixel( $t_im, $x, $y, $transparent );
           }
         }
         imageCopyResampled($t_im, $o_im, 0, 0, 0, 0, $t_wd, $t_ht, $o_wd, $o_ht);
         imagePNG($t_im, $image_name);
...
?>

It seems that it is not working correctly. In my test the source picture in ImageCopyResampled() is smaller than the destination picture $t_im, the remaining part is white !

I changed transparent alpha channel to 127, and I tried to replace loops with imagefilledrectangle().

It works fine and these resource greedy loops are removed.

Here is the code with my change.

<?
...
         $t_im = imageCreateTrueColor($t_wd,$t_ht);
         imageAntiAlias($t_im,true);
         imagealphablending($t_im, false);
         imagesavealpha($t_im,true);
         $transparent = imagecolorallocatealpha($t_im, 255, 255, 255, 127);
         imagefilledrectangle($t_img, 0, 0, $t_wd, $t_ht, $transparent);
         imageCopyResampled($t_im, $o_im, 0, 0, 0, 0, $t_wd, $t_ht, $o_wd, $o_ht);
         imagePNG($t_im, $image_name);
...
?>
del at kartoon dot net 05-May-2005 10:38
This snippet allows you to grab a thumbnail from the center of a large image.  This was used for a client photo gallery for art to give a teaser of the image to come (only a small portion).  You could get dynamic with this value.  I also put in a scaling factor in case you want to scale down first before chopping.

<?php
// The file
$filename = 'moon.jpg';
$percent = 1.0; // if you want to scale down first
$imagethumbsize = 200; // thumbnail size (area cropped in middle of image)
// Content type
header('Content-type: image/jpeg');

// Get new dimensions
list($width, $height) = getimagesize($filename);
$new_width = $width * $percent;
$new_height = $height * $percent;

// Resample
$image_p = imagecreatetruecolor($imagethumbsize , $imagethumbsize);  // true color for best quality
$image = imagecreatefromjpeg($filename);

// basically take this line and put in your versin the -($new_width/2) + ($imagethumbsize/2) & -($new_height/2) + ($imagethumbsize/2) for
// the 2/3 position in the 3 and 4 place for imagecopyresampled
// -($new_width/2) + ($imagethumbsize/2)
// AND
// -($new_height/2) + ($imagethumbsize/2)
// are the trick
imagecopyresampled($image_p, $image, -($new_width/2) + ($imagethumbsize/2), -($new_height/2) + ($imagethumbsize/2), 0, 0, $new_width , $new_width , $width, $height);

// Output

imagejpeg($image_p, null, 100);
?>