PHP Thumbnail Image script, jpg colours looking funny on thumbnail.

I am having problems with this code, it resizes gifs fine but the colour in jpeg is terrible. can anyone give me a hand.

example code works like so.
Example: <img src="image.php?img=/imgs/logo.png;sm,200" border="1" alt="[Image]" align="left">
This will scale the image down to a maximum of 200px while keeping the aspect ratio.

<?php
session_register( 'imgdir' );
session_register( 'imgext' );
$imgext = '.jpg';
*/

if( ! defined( 'IMG_IP' ) ) { define( 'IMG_IP', 1 ); } // Image interpolation -- size up from original
if( ! defined( 'IMG_MAXSIZE' ) ) { define( 'IMG_MAXSIZE', 999999999 ); } // can't be any larger

class Image
{
    var $data;
    var $filename;
    var $img;
    
    function Image( $mixed = 0 )
    {
        if( empty( $mixed ) ) { return $this; }
        if( ! $this->ImageFromFile( $mixed ) ) {
            if( ! $this->ImageFromData( $mixed ) ) {
                return( 0 );
            }
        }
        return $this;    
    }
    
    function ImageFromFile( $f )
    {
        if( ( $fp = fopen( $f, 'rb' ) ) || ($fp = fopen($_SERVER['DOCUMENT_ROOT'] . $f, 'rb')) ) {
            $this->data = fread( $fp, ( filesize( $f ) ? filesize( $f ) : IMG_MAXSIZE ) );
            $this->filename = $f;
            return $this->ImageFromData( $this->data );
        } else {
            return( 0 );
        }
        return( 1 );
    }
    
    function ImageFromData( $d )
    {
        if( $this->img = ImageCreateFromString( $d ) ) {
            return( 1 );
        }
        return( 0 );
    }
    
    function save( $filename = '', $print = 0 )
    {
        if( empty( $filename ) ) {
            if( empty( $this->filename ) ) {
                return 0;
            } else {
                $filename = $this->filename;
            }
        }
        //print $filename;
        $filetype = substr( strrchr( $filename, '.' ), 1 );
        switch( $filetype ) {
            case 'jpg':
            case 'jpeg':
                if( ImageTypes() & IMG_JPG ) {
                    if( $print ) {
                        header( "Content-type: image/jpeg\n\n" );
                        return ImageJPEG( $this->img );
                    } else return ImageJPEG( $this->img, $filename );
                }
                break;
            case 'png':
                if( ImageTypes() & IMG_PNG ) {
                    if( $print ) {
                        header( "Content-type: image/png\n\n" );
                        return ImagePNG( $this->img );
                    } else return ImagePNG( $this->img, $filename );
                }
                break;
            case 'gif':
                if( ImageTypes() & IMG_GIF ) {
                    if( $print ) {
                        header( "Content-type: image/gif\n\n" );
                        return ImageGIF( $this->img );
                    } else return ImageGIF( $this->img, $filename );
                }
                break;
            case 'bmp':
                if( ImageTypes() & IMG_WBMP ) {
                    if( $print ) {
                        header( "Content-type: image/wbmp\n\n" );
                        return ImageWBMP( $this->img );
                    } else return ImageWBMP( $this->img, $filename );
                }
                break;
        }
    }
    
    function p()
    {
        return $this->save( 0, 1 );
    }
    
    
    function scale_image( $newWidth = 0, $newHeight = 0, $ratio = 0, $copy = '' )
    {
        if( ! empty( $copy ) ) {
            global $$copy;
        }

        $width = imageSX( $this->img );
        $height = imageSY( $this->img );
        if( empty( $newWidth ) &&  empty( $newHeight ) ) {
            // no dimensions, check ratio
            if( empty( $ratio ) ) {
                // nothing to scale to, return
                return( 0 );
            } else {
                // get dimensions from ratio
                $dimensions[] = round( $width * $ratio );
                $dimensions[] = round( $height * $ratio );
            }
        } else if( empty( $newWidth ) || empty( $newHeight ) ) {
            // we have one dimension, use this as the max and run through ratio()
            $dimensions = $this->ratio( ( ! empty( $newWidth ) ? $newWidth : $newHeight ) );
        } else {
            $dimensions = array( $newWidth, $newHeight );
        }

        $newImg = imageCreate( $dimensions[0], $dimensions[1] );
        imageCopyResized( $newImg, $this->img, 0, 0, 0, 0, $dimensions[0], $dimensions[1], $width, $height );
        if( empty( $copyScaled ) ) {
            imageDestroy( $this->img );
            $this->img = imageCreate( $dimensions[0], $dimensions[1] );
            imageCopy( $this->img, $newImg, 0, 0, 0, 0, $dimensions[0], $dimensions[1] );
        } else {
            $$copy = new Image( imageJpeg( $newImg ) );
        }
        imageDestroy( $newImg );
        return( 1 );
    }

    function ratio( $max )
    {
        $width = imageSX( $this->img );
        $height = imageSY( $this->img );
        if( empty( $max ) ) { return( 0 ); }
        $ratio = round( ( $max / max( $width, $height ) ), 2 );
        // work out interpolation (scale larger than original)
        if( ! IMG_IP ) {
            if( $ratio < 1 ) {
                $width = round( $width * $ratio );
                $height = round( $height * $ratio );
            }
        } else {
            $width = round( $width * $ratio );
            $height = round( $height * $ratio );
        }
        return( Array( $width, $height, $ratio ) );

    }
    
    function overlay( $img, $ovr, $copy = '' )
    {
        
    }
    
    function parseImgTag( $tag )
    {
        /*format '$url;$args'
            args: '$attr,$param[[,$param],$paramX];$attr,$param[[,$param],$paramX]'
        */
        $url = substr( $tag, 0, (strpos( $tag, ';' )?strpos($tag,';'):strlen($tag)) );
        //print $url;
        // load image or die
        
        if( !$this->ImageFromFile( $url ) ) {
            die( "Could not load image" );
        }
        
        $args = substr( strchr( $tag, ';' ), 1 );
        // parse args
        $commands = explode( ';', $args );
        foreach( $commands as $command ) {
            $attr = substr( $command, 0, strpos( $command, ',' ) );
            $params = explode( ',', substr( strchr( $command, ',' ), 1 ) );
            switch( $attr ) {
                /* s.. Scale functions as follows
                    s,width,height -- scale to desired dimensions
                    sm,max -- scale to maximum
                    sr,ratio -- scale to ratio (relative to 1.0)
                */
                case 's':
                    $this->scale_image( $params[0], $params[1] );
                    break;
                case 'sm':
                    $this->scale_image( $params[0] );
                    break;
                case 'sr':
                    $this->scale_image( 0, 0, $params[0] );
                    break;
            }
            
        }
        $this->p();
        
    }

}


/* main logic if called directly */

if($_SERVER['PATH_TRANSLATED'] == __FILE__) {
    if(isset($_GET['img']) && !empty($_GET['img'])) {
        $imgO = new Image();

        $imgO->parseImgTag(urldecode($_GET['img']));
    }
}

?> 

PHP:

 

You might want to try using the truecolor method. I think that might be the problem.

Replace

 
$newImg = imageCreate( $dimensions[0], $dimensions[1] );
imageCopyResized( $newImg, $this->img, 0, 0, 0, 0, $dimensions[0], $dimensions[1], $width, $height );

Code (markup):

with

$newImg = imagecreatetruecolor( $dimensions[0], $dimensions[1] );
imagecopyresampled($newImg, $this->img, 0, 0, 0, 0, $dimensions[0], $dimensions[1], $width, $height);

Code (markup):

I always use the truecolor method for thumbnail generation and it produces pretty good results as long as you maintain a proper aspect ratio.

Note that the second line is changed from imageCopyResized to imagecopyresampled.

 

imagejpeg() has a third parameter quality:

ImageJPEG( $this->img, null, 100 );
ImageJPEG( $this->img, $filename, 100);

PHP:

 

Thanks for the help lads
Image truecolor was the fix.
Needed to be added in twice though.

$newImg = imagecreatetruecolor( $dimensions[0], $dimensions[1] );
imageCopyResampled($newImg, $this->img, 0, 0, 0, 0, $dimensions[0], $dimensions[1], $width, $height);
        if( empty( $copyScaled ) ) {
            imageDestroy( $this->img );
            $this->img = imagecreatetruecolor( $dimensions[0], $dimensions[1] );

PHP:

Thanks Again.