getimagesize()

(PHP 4, PHP 5, PHP 7)

取得图像大小

说明

getimagesize(string $filename[,array &$imageinfo]): array

getimagesize()函数将测定任何GIF，JPG，PNG，SWF，SWC，PSD，TIFF，BMP，IFF，JP2，JPX，JB2，JPC，XBM或WBMP图像文件的大小并返回图像的尺寸以及文件类型和一个可以用于普通HTML文件中IMG标记中的 height/width 文本字符串。

如果不能访问$filename指定的图像或者其不是有效的图像，getimagesize()将返回FALSE并产生一条E_WARNING级的错误。

Note:

对JPC，JP2，JPX，JB2，XBM和WBMP的支持自 PHP 4.3.2 起可用。对SWC的支持自 PHP 4.3.0 起可用。对TIFF的支持是 PHP 4.2.0 添加的。

Note: JPEG 2000 支持是 PHP 4.3.2 添加的。注意 JPC 和 JP2 可以有不同的色彩深度的成分。此情况下，“bits”的值是碰到的最高的位深度。此外，JP2 文件可能包含有多个 JPEG 2000 代码流，此情况下，getimagesize()返回此文件顶层中碰到的第一个代码流的值。

Note:本函数不需要 GD 图像库。

返回一个具有四个单元的数组。索引 0 包含图像宽度的像素值，索引 1 包含图像高度的像素值。索引 2 是图像类型的标记：1 = GIF，2 = JPG，3 = PNG，4 = SWF，5 = PSD，6 = BMP，7 = TIFF(intel byte order)，8 = TIFF(motorola byte order)，9 = JPC，10 = JP2，11 = JPX，12 = JB2，13 = SWC，14 = IFF，15 = WBMP，16 = XBM。这些标记与 PHP 4.3.0 新加的 IMAGETYPE 常量对应。索引 3 是文本字符串，内容为“height="yyy" width="xxx"”，可直接用于 IMG 标记。

getimagesize（文件）

<?php
list($width, $height, $type, $attr) = getimagesize("img/flag.jpg");
echo "<img src=\"img/flag.jpg\" $attr>";
?>

URL 支持是 PHP 4.0.5 添加的。

getimagesize（URL）

<?php
$size = getimagesize("http://www.example.com/gifs/logo.gif");
// if the file name has space in it, encode it properly
$size = getimagesize("http://www.example.com/gifs/lo%20go.gif");
?>

对于JPG图像，还会多返回两个索引：channels和bits。channels对于 RGB 图像其值为 3，对于 CMYK 图像其值为 4。bits是每种颜色的位数。

自 PHP 4.3.0 起，bits和channels对于其它图像类型也存在。但是这些值可能会把人搞糊涂。例如，GIF总是对每个像素使用 3 个 channel，但是对于动画GIF来说每个像素的位数无法通过全局颜色表计算出来。

某些格式可能不包含图像或者包含多个图像。此种情况下，getimagesize()可能不能用来准确测定图像的大小。此时getimagesize()将返回零作为宽度和高度。

自 PHP 4.3.0 起，getimagesize()还会返回额外的参数mime，符合该图像的 MIME 类型。此信息可以用来在 HTTP Content-type 头信息中发送正确的信息：

getimagesize()和 MIME 类型

<?php
$size = getimagesize($filename);
$fp=fopen($filename, "rb");
if ($size && $fp) {
  header("Content-type: {$size['mime']}");
  fpassthru($fp);
  exit;
} else {
  // error
}
?>

可选的$imageinfo参数允许从图像文件中提取一些扩展信息。目前，这将以一个关联数组返回不同的JPG APP 标识。某些程序用这些 APP 标识来在图像中嵌入文本信息。一个非常常见的是 APP13 标识中嵌入的IPTC» http://www.iptc.org/信息。可以用iptcparse()函数来将二进制的 APP13 标识解析为可读的信息。

getimagesize()返回 IPTC

<?php
$size = getimagesize("testimg.jpg", &$info);
if (isset($info["APP13"])) {
    $iptc = iptcparse($info["APP13"]);
    var_dump($iptc);
}
?>

参见image_type_to_mime_type()，exif_imagetype()，exif_read_data()和exif_thumbnail()。

参数

$filename

This parameter specifies the file you wish to retrieve information about. It can reference a local file or(configuration permitting)a remote file using one of the supported streams.

$imageinfo

This optional parameter allows you to extract some extended information from the image file. Currently, this will return the different JPG APP markers as an associative array. Some programs use these APP markers to embed text information in images. A very common one is to embed » IPTC information in the APP13 marker. You can use the iptcparse() function to parse the binary APP13 marker into something readable.

返回值

Returns an array with 7 elements.

Index 0 and 1 contains respectively the width and the height of the image.

Note:

Some formats may contain no image or may contain multiple images. In these cases,getimagesize() might not be able to properly determine the image size.getimagesize() will return zero for width and height in these cases.

Index 2 is one of theIMAGETYPE_XXXconstants indicating the type of the image.

Index 3 is a text string with the correctheight="yyy" width="xxx"string that can be used directly in an IMG tag.

mimeis the correspondant MIME type of the image. This information can be used to deliver images with the correct HTTPContent-typeheader:

getimagesize() and MIME types

<?php
$size = getimagesize($filename);
$fp = fopen($filename, "rb");
if ($size && $fp) {
    header("Content-type: {$size['mime']}");
    fpassthru($fp);
    exit;
} else {
    // error
}
?>

channelswill be 3 for RGB pictures and 4 for CMYK pictures.

bitsis the number of bits for each color.

For some image types, the presence ofchannelsandbitsvalues can be a bit confusing. As an example,GIF always uses 3 channels per pixel, but the number of bits per pixel cannot be calculated for an animated GIF with a global color table.

On failure,FALSE is returned.

错误／异常

If accessing the$filenameimage is impossible, or if it isn't a valid picture,getimagesize() will generate an error of level E_WARNING. On read error,getimagesize() will generate an error of level E_NOTICE.

更新日志

范例

getimagesize() example

<?php
list($width, $height, $type, $attr) = getimagesize("img/flag.jpg");
echo "<img src=\"img/flag.jpg\" $attr alt=\"getimagesize() example\" />";
?>

Example #7 getimagesize(URL)

<?php
$size = getimagesize("http://www.example.com/gifs/logo.gif");
// if the file name has space in it, encode it properly
$size = getimagesize("http://www.example.com/gifs/lo%20go.gif");
?>

Example #8 getimagesize()returning IPTC

<?php
$size = getimagesize("testimg.jpg", $info);
if (isset($info["APP13"])) {
    $iptc = iptcparse($info["APP13"]);
    var_dump($iptc);
}
?>

注释

Note:

此函数不需要 GD 图象库。

参见

• image_type_to_mime_type()取得 getimagesize，exif_read_data，exif_thumbnail，exif_imagetype 所返回的图像类型的 MIME 类型
• exif_imagetype()判断一个图像的类型
• exif_read_data()从 JPEG 或 TIFF 文件中读取 EXIF 头信息
• exif_thumbnail()取得嵌入在 TIFF 或 JPEG 图像中的缩略图

As noted below, getimagesize will download the entire image before it checks for the requested information. This is extremely slow on large images that are accessed remotely. Since the width/height is in the first few bytes of the file, there is no need to download the entire file. I wrote a function to get the size of a JPEG by streaming bytes until the proper data is found to report the width and height:
<?php
// Retrieve JPEG width and height without downloading/reading entire image.
function getjpegsize($img_loc) {
  $handle = fopen($img_loc, "rb") or die("Invalid file stream.");
  $new_block = NULL;
  if(!feof($handle)) {
    $new_block = fread($handle, 32);
    $i = 0;
    if($new_block[$i]=="\xFF" && $new_block[$i+1]=="\xD8" && $new_block[$i+2]=="\xFF" && $new_block[$i+3]=="\xE0") {
      $i += 4;
      if($new_block[$i+2]=="\x4A" && $new_block[$i+3]=="\x46" && $new_block[$i+4]=="\x49" && $new_block[$i+5]=="\x46" && $new_block[$i+6]=="\x00") {
        // Read block size and skip ahead to begin cycling through blocks in search of SOF marker
        $block_size = unpack("H*", $new_block[$i] . $new_block[$i+1]);
        $block_size = hexdec($block_size[1]);
        while(!feof($handle)) {
          $i += $block_size;
          $new_block .= fread($handle, $block_size);
          if($new_block[$i]=="\xFF") {
            // New block detected, check for SOF marker
            $sof_marker = array("\xC0", "\xC1", "\xC2", "\xC3", "\xC5", "\xC6", "\xC7", "\xC8", "\xC9", "\xCA", "\xCB", "\xCD", "\xCE", "\xCF");
            if(in_array($new_block[$i+1], $sof_marker)) {
              // SOF marker detected. Width and height information is contained in bytes 4-7 after this byte.
              $size_data = $new_block[$i+2] . $new_block[$i+3] . $new_block[$i+4] . $new_block[$i+5] . $new_block[$i+6] . $new_block[$i+7] . $new_block[$i+8];
              $unpacked = unpack("H*", $size_data);
              $unpacked = $unpacked[1];
              $height = hexdec($unpacked[6] . $unpacked[7] . $unpacked[8] . $unpacked[9]);
              $width = hexdec($unpacked[10] . $unpacked[11] . $unpacked[12] . $unpacked[13]);
              return array($width, $height);
            } else {
              // Skip block marker and read block size
              $i += 2;
              $block_size = unpack("H*", $new_block[$i] . $new_block[$i+1]);
              $block_size = hexdec($block_size[1]);
            }
          } else {
            return FALSE;
          }
        }
      }
    }
  }
  return FALSE;
}
?>

Note: getimage size doesn't attempt to validate image file formats
It is possible for malformed GIF images to contain PHP and still have valid dimensions.
Programmers need to ensure such images are validated by other tools, or never treated as PHP or other executable types (enforcing appropriate extensions, avoiding user controlled renaming, restricting uploaded images to areas of the website where PHP is not enabled).
http://ha.ckers.org/blog/20070604/passing-malicious-php-through-getimagesize/

If you want to "convert" value returned by "getimagesize()" as index "2" into something more human-readable, you may consider using a function like this one:
  $imageTypeArray = array
  (
    0=>'UNKNOWN',
    1=>'GIF',
    2=>'JPEG',
    3=>'PNG',
    4=>'SWF',
    5=>'PSD',
    6=>'BMP',
    7=>'TIFF_II',
    8=>'TIFF_MM',
    9=>'JPC',
    10=>'JP2',
    11=>'JPX',
    12=>'JB2',
    13=>'SWC',
    14=>'IFF',
    15=>'WBMP',
    16=>'XBM',
    17=>'ICO',
    18=>'COUNT' 
  );
  
  $size = getimagesize($filename);
  
  $size[2] = $imageTypeArray[$size[2]];
Or something similar.

Well, I am making a script which will resize the image when uploaded, however, i am making a multi-uploader, so i came across with a problem: an efficient way of getting a pictures height and width and storing them in an array to resize later. This is what i came up with:
<?php
$links = array("test1.jpg", "test2.png");
$sizearray = array();
$count = count($links);
for($i = 0; $i < $count; $i++) {
  $size = getimagesize($links[$i]);
  list($width, $height) = $size;
  $sizearray[$links[$i]] = array("width" => $width, "height" => $height);
}
print_r($sizearray);
// which will print out: Array ( [test1.jpg] => Array ( [width] => 300 [height] => 400 ) [test2.png] => Array ( [width] => 680 [height] => 100 ) )
?>

Note that, if you're going to be a good programmer and use named constatnts (IMAGETYPE_JPEG) rather than their values (2), you want to use the IMAGETYPE variants - IMAGETYPE_JPEG, IMAGETYPE GIF, IMAGETYPE_PNG, etc. For some reason, somebody made a horrible decision, and IMG_PNG is actually 4 in my version of PHP, while IMAGETYPE_PNG is 3. It took me a while to figure out why comparing the type against IMG_PNG was failing...

It's always good to check out an image's dimensions while attempting to upload to your server or database...especially if it's going to be displayed on a page that doesn't accomodate images beyond a particular size.
<?php
$tmpName = $_FILES['userfile']['tmp_name'];
    
list($width, $height, $type, $attr) = getimagesize($tmpName);
if($width>275 || $height>275)
{
die("exceeded image dimension limits.");
}
?>

I wanted to use getimagesize() on .SWF files stored in the database as blob data and couldn't find a simple solution, so I created my own.
I am releasing this code under the MIT license to save everyone some time:
<?php
/*
  ----------------------------------------------------------------------
  PHP Blob Data As File Stream v1.0 (C) 2012 Alex Yam <alexyam@live.com>
  This code is released under the MIT License.
  ----------------------------------------------------------------------
  [Summary]
  A simple class for PHP functions to read and write blob data as a file
  using a stream wrapper.
  Particularly useful for running getimagesize() to get the width and
  height of .SWF Flash files that are stored in the database as blob data.
  Tested on PHP 5.3.10.
  ----------------------------------------------------------------------  
  [Usage Example]
  //Include
    include('./blob_data_as_file_stream.php');
  //Register the stream wrapper
    stream_wrapper_register("BlobDataAsFileStream", "blob_data_as_file_stream");
  //Fetch a .SWF file from the Adobe website and store it into a variable.
  //Replace this with your own fetch-swf-blob-data-from-database code.
    $swf_url = 'http://www.adobe.com/swf/software/flash/about/flashAbout_info_small.swf';
    $swf_blob_data = file_get_contents($swf_url);
  
  //Store $swf_blob_data to the data stream
    blob_data_as_file_stream::$blob_data_stream = $swf_blob_data;
  
  //Run getimagesize() on the data stream
    $swf_info = getimagesize('BlobDataAsFileStream://');
    var_dump($swf_info);
  ----------------------------------------------------------------------
  [Usage Output]
  array(5) {
   [0]=>
   int(159)
   [1]=>
   int(91)
   [2]=>
   int(13)
   [3]=>
   string(23) "width="159" height="91""
   ["mime"]=>
   string(29) "application/x-shockwave-flash"
  }
*/
class blob_data_as_file_stream {
  private static $blob_data_position = 0;
  public static $blob_data_stream = '';
  public static function stream_open($path,$mode,$options,&$opened_path){
    static::$blob_data_position = 0;
    return true;
  }
  public static function stream_seek($seek_offset,$seek_whence){
    $blob_data_length = strlen(static::$blob_data_stream);
    switch ($seek_whence) {
      case SEEK_SET:
        $new_blob_data_position = $seek_offset;
        break;
      case SEEK_CUR:
        $new_blob_data_position = static::$blob_data_position+$seek_offset;
        break;
      case SEEK_END:
        $new_blob_data_position = $blob_data_length+$seek_offset;
        break;
      default:
        return false;
    }
    if (($new_blob_data_position >= 0) AND ($new_blob_data_position <= $blob_data_length)){
      static::$blob_data_position = $new_blob_data_position;
      return true;
    }else{
      return false;
    }
  }
  public static function stream_tell(){
    return static::$blob_data_position;
  }
  public static function stream_read($read_buffer_size){
    $read_data = substr(static::$blob_data_stream,static::$blob_data_position,$read_buffer_size);
    static::$blob_data_position += strlen($read_data);
    return $read_data;
  }
  public static function stream_write($write_data){
    $write_data_length=strlen($write_data);
    static::$blob_data_stream = substr(static::$blob_data_stream,0,static::$blob_data_position).
      $write_data.substr(static::$blob_data_stream,static::$blob_data_position+=$write_data_length);
    return $write_data_length;
  }
  public static function stream_eof(){
    return static::$blob_data_position >= strlen(static::$blob_data_stream);
  }
}
?>

Could be useful (didn´t know where to post it):
function getImageErrors( $filename, $type = "", $minWidth = 0, $minHeight = 0, $maxWidth = 0, $maxHeight = 0, $maxFileSize = 0 )
{
  $errors = array();
  if ( file_exists( $filename ) )
  {
    $ending = substr( $filename, strpos( $filename, "." ) );
    if ( is_array( $type ) )
    {
      $isTypeOf = false;
      foreach( $type as $eachtype )
      {
        if ( $ending == $eachtype )
        {
          $isTypeOf = true;
        }
      }
      if ( ! $isTypeOf )
      {
        $errors[ 'type' ] = $ending;
      }
    }
    elseif ( $type != "" )
    {
      if ( $ending != $type )
      {
        $errors[ 'type' ] = $ending;
      }
    }
    $size = getimagesize( $filename );
    if ( $size[ 0 ] < $minWidth )
    {
      $errors[ 'minWidth' ] = $size[ 0 ];
    }
    if ( $size[ 1 ] < $minHeight )
    {
      $errors[ 'minHeight' ] = $size[ 1 ];
    }
    if ( ( $maxWidth > $minWidth ) && ( $size[ 0 ] > $maxWidth ) )
    {
      $errors[ 'maxWidth' ] = $size[ 0 ];
    }
    if ( ( $maxHeight > $minHeight ) && ( $size[ 1 ] > $maxHeight ) )
    {
      $errors[ 'maxHeight' ] = $size[ 1 ];
    }
    if ( ( $maxFileSize > 0 ) && ( filesize( $filename ) > $maxFileSize ) )
    {
      $errors[ 'maxFileSize' ] = filesize( $filename );
    }
  }
  else
  {
    $errors[ 'filename' ] = "not existing";
  }
  return ( count( $errors ) > 0 ? $errors : null );
}

This function returns the width and height of a JPEG image from a string, allowing the dimensions of images stored in a database to be retrieved without writing them to the disk first, or using "imagecreatefromstring" which is very slow in comparison.
<?PHP
function getJPEGImageXY($data) {
    $soi = unpack('nmagic/nmarker', $data);
    if ($soi['magic'] != 0xFFD8) return false;
    $marker = $soi['marker'];
    $data  = substr($data, 4);
    $done  = false;
    while(1) {
        if (strlen($data) === 0) return false;
        switch($marker) {
            case 0xFFC0:
                $info = unpack('nlength/Cprecision/nY/nX', $data);
                return array($info['X'], $info['Y']);
                break;
            default:
                $info  = unpack('nlength', $data);
                $data  = substr($data, $info['length']);
                $info  = unpack('nmarker', $data);
                $marker = $info['marker'];
                $data  = substr($data, 2);
                break;
        }
    }
}
?>
Doing this 10,000 times takes 0.43 seconds, compared with using imagecreatefromstring/imagesx/imagesy which takes around 1.52 seconds to do the same.
Do not use this instead of getimagesize when dealing with files, getimagesize is much faster coming in at 0.15 seconds.

i made function img_resize($path,$tmp_name,$new_name,$new_width)
this could be useful.
<?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;
}
?>

The list of defined IMAGETYPE_ constants is on the manual page for exif_imagetype:
http://www.php.net/manual/en/function.exif-imagetype.php

Seems the various ways people are trying to proportionaly scale an image, up or down, could be more straight forward if one remembers ones algebra.
The formula is, y = mx, where m is the slope of the line. This is the ratio of y:x or m = y/x.
So if...
// max values for x and y
$y_max = 600;
$x_max = 800;
// image size
$y1 = 2000;
$x1 = 3000;
// use width for scaling
if ($x1 > $x_max)
{
  // find slope 
  $m = $y1/$x1;
  // set x side to max
  $x2 = $x_max;
  // set y side to a proportional size
  $y2 = $m * $x1;
}
The new image proportionally scaled will be x2 = 800, y2 = 533 (rounded).
To do it from the y side, simply reverse the x's and y's.

How about this for cropping images...
<?php
$imgfile = "img.jpg";
$cropStartX = 300;
$cropStartY = 250;
$cropW  = 200;
$cropH  = 200;
// Create two images
$origimg = imagecreatefromjpeg($imgfile);
$cropimg = imagecreatetruecolor($cropW,$cropH);
// Get the original size
list($width, $height) = getimagesize($imgfile);
// Crop
imagecopyresized($cropimg, $origimg, 0, 0, $cropStartX, $cropStartY, $width, $height, $width, $height);
// TODO: write code to save new image
// or, just display it like this:
header("Content-type: image/jpeg");
imagejpeg($cropimg);
// destroy the images
imagedestroy($cropimg);
imagedestroy($origimg);
?>

Here is the function which determines whether the PNG image contains alpha or not:
<?php
function is_alpha_png($fn){
 return (ord(@file_get_contents($fn, NULL, NULL, 25, 1)) == 6);
}
?>
The color type of PNG image is stored at byte offset 25. Possible values of that 25'th byte is:
 * 0 - greyscale
 * 2 - RGB
 * 3 - RGB with palette
 * 4 - greyscale + alpha
 * 6 - RGB + alpha

Returns a array with 4 elements.
The 0 index is the width of the image in pixels.
The 1 index is the height of the image in pixels.
The 2 index is a flag for the image type:
1 = GIF, 2 = JPG, 3 = PNG, 4 = SWF, 5 = PSD, 6 = BMP, 7 = TIFF(orden de bytes intel), 8 = TIFF(orden de bytes motorola), 9 = JPC, 10 = JP2, 11 = JPX, 12 = JB2, 13 = SWC, 14 = IFF, 15 = WBMP, 16 = XBM. 
The 3 index contains ' height="yyy" width="xxx" '

Rather than making a lengthy function that essentially runs twice (once as width, once as height) I came up with a helpful function that uses variable variables to set a maximum height/width. Hope someone finds this helpful.
function scaleimage($location, $maxw=NULL, $maxh=NULL){
  $img = @getimagesize($location);
  if($img){
    $w = $img[0];
    $h = $img[1];
    $dim = array('w','h');
    foreach($dim AS $val){
      $max = "max{$val}";
      if(${$val} > ${$max} && ${$max}){
        $alt = ($val == 'w') ? 'h' : 'w';
        $ratio = ${$alt} / ${$val};
        ${$val} = ${$max};
        ${$alt} = ${$val} * $ratio;
      }
    }
    return("<img src='{$location}' alt='image' width='{$w}' height='{$h}' />");
  }
}

There's a code snippet for getting JPEG image dimensions by getting only first few bytes of the file, but it doesn't work for PNG files, so I wrote one. It will download only the first 24 bytes instead of the whole image, and thus being much faster than getimagesize() and it will save bandwidth at the same time:
<?php
// Retrieve PNG width and height without downloading/reading entire image.
function getpngsize( $img_loc ) {
  $handle = fopen( $img_loc, "rb" ) or die( "Invalid file stream." );
  if ( ! feof( $handle ) ) {
    $new_block = fread( $handle, 24 );
    if ( $new_block[0] == "\x89" &&
      $new_block[1] == "\x50" &&
      $new_block[2] == "\x4E" &&
      $new_block[3] == "\x47" &&
      $new_block[4] == "\x0D" &&
      $new_block[5] == "\x0A" &&
      $new_block[6] == "\x1A" &&
      $new_block[7] == "\x0A" ) {
        if ( $new_block[12] . $new_block[13] . $new_block[14] . $new_block[15] === "\x49\x48\x44\x52" ) {
          $width = unpack( 'H*', $new_block[16] . $new_block[17] . $new_block[18] . $new_block[19] );
          $width = hexdec( $width[1] );
          $height = unpack( 'H*', $new_block[20] . $new_block[21] . $new_block[22] . $new_block[23] );
          $height = hexdec( $height[1] );
          return array( $width, $height );
        }
      }
    }
  return false;
}
?>

For some images, using getimagesize() without the second parameter will return the correct info, but when you add the second parameter it will return false. This is most likely a bug (and it has been reported as such), but meanwhile, if you encounter this problem, a workaround is to use exif_read_data().

When validating images, allways check both, image type *AND* file extension!
Because most image types allow sections for comments or other irrelevant data. Those section can be used to infiltrate php code onto the server. If these files are stored as sent by the client, files with a ".php" extension can be executed and do tremendous harm.

A simple piece of code i wrote to proportionally resize an image to a max height and width then display it
<?php
// Max height and width
$max_width = 100;
$max_height = 100;
// Path to your jpeg
$upfile '/path/to/file.jpg';
  Header("Content-type: image/jpeg");
  
  $size = GetImageSize($upfile); // Read the size
     $width = $size[0];
     $height = $size[1];
     
     // Proportionally resize the image to the
     // max sizes specified above
     
     $x_ratio = $max_width / $width;
     $y_ratio = $max_height / $height;
     if( ($width <= $max_width) && ($height <= $max_height) )
     {
        $tn_width = $width;
        $tn_height = $height;
     }
     elseif (($x_ratio * $height) < $max_height)
     {
        $tn_height = ceil($x_ratio * $height);
        $tn_width = $max_width;
     }
     else
     {
        $tn_width = ceil($y_ratio * $width);
        $tn_height = $max_height;
     }
   // Increase memory limit to support larger files
   
   ini_set('memory_limit', '32M');
   
   // Create the new image!
   $src = ImageCreateFromJpeg($upfile);
   $dst = ImageCreateTrueColor($tn_width, $tn_height);
   ImageCopyResized($dst, $src, 0, 0, 0, 0, $tn_width, $tn_height, $width, $height);
   ImageJpeg($dst);
// Destroy the images
ImageDestroy($src);
ImageDestroy($dst);
?>

Heres a easy way to scale images to the <td> that they are in
*this is broken up so anyone can understand it :)
<?
$imageinfo = getimagesize("images/picture.jpg");
     
$ix=$imageinfo[0];
$iy=$imageinfo[1];
$widthscale = $ix/175; //<TD> WIDTH
$heightscale = $iy/175; //<TD> HEIGHT
if($widthscale < 1)
$nwidth = $ix*$widthscale;
else
$nwidth = $ix/$widthscale;
if($heightscale < 1)
$nheight = $iy*$heightscale;
else
$nheight = $iy/$heightscale;
?>

I'm sorry for they other scripts, but I made one mistake about the image resizing... here is a working script !
<?
  // Some configuration variables !
  $maxWidth = 90;
  $maxHeight = 90;
  $maxCols = 8;
  $webDir = "https://localhost/images/";
  $localDir = $_SERVER['DOCUMENT_ROOT']."/images/";
  $AutorisedImageType = array ("jpg", "jpeg", "gif", "png");
?>
<center>
<table border='1' cellspacing='5' cellpadding='5' style="border-collapse:collapse; border-style: dotted">
<tr>
  <?
  // Open localDir
  $dh = opendir($localDir);
  while (false !== ($filename = readdir($dh))) {
    $filesArray[] = $filename;
  }
  // Display and resize
  foreach ($filesArray as $images) {
  
    $ext = substr($images, strpos($images, ".")+1, strlen($images));
    
    if( in_array($ext, $AutorisedImageType) ) {
      list($width, $height, $type, $attr) = @getimagesize( $localDir.$images );
      $xRatio = $maxWidth / $width; 
      $yRatio = $maxHeight / $height; 
      
      if ( ($width <= $maxWidth) && ($height <= $maxHeight) ) { 
       $newWidth = $width; 
       $newHeight = $height; 
      } 
      else if (($xRatio * $height) < $maxHeight) { 
       $newHeight = ceil($xRatio * $height); 
       $newWidth = $maxWidth; 
      } 
      else { 
       $newWidth = ceil($yRatio * $width); 
       $newHeight = $maxHeight; 
      } 
      
      if($i == $maxCols) {
        echo "</tr><tr>";
        $i = 0;
      }
      echo "<td align='center' valign='middle' width='$maxWidth' height='$maxHeight'><img src='".$webDir.$images."' width='$newWidth' height='$newHeight'></td>";
      $i++;
    }
  }
?>
</tr>
</table>
</center>

Correction: to find $y2 it should be...
// set y side to a proportional size
$y2 = $m * $x_max; // not $x1
Thanks Norbert =)

Note that if you specify a remote file (via a URL) to check the size of, PHP will first download the remote file to your server.
If you're using this function to check the size of user provided image links, this could constitute a security risk. A malicious user could potentially link to a very large image file and cause PHP to download it. I do not know what, if any, file size limits are in place for the download. But suppose the user provided a link to an image that was several gigabytes in size?
It would be nice if there were a way to limit the size of the download performed by this function. Hopefully there is already a default with some sensible limits.