GD Thumbnailing Probs

[pointybeard]

Hi,
I am writing an eCommerce site for a client and when showing products i wish to show a thumbnail which is generated on the fly from a picture. It works, but not totally correctly. This is my code (I borrowed it from somewhere and tweaked it slightly)

<?php

    $error = False;
    
    $system = explode(".", $image);
    
    // check if the 'image' parameter has been given
    if (!isset($image)) // if not generate an error
        $error = True;
        
    // check if the 'img_size' parameter has been given
    if (!isset($img_size) && ($resize != 'no')) // if not generate an error
        $error = True;
    
    if($resize != 'no')    {
        // ensure that $img_size is an integer 
        $img_size = (integer) $img_size;
        
        // check that the size asked for is sensible
        if ($img_size < 20)// if not generate an error
            $error = True;    
    }
    
    if(!$bigimage=@imagecreatefromjpeg($image))
    $error = true;        

    
    if($error){ // generate an error image
        $img = ImageCreate(123, 100);                
        $bg = ImageColorAllocate($img, 255, 255, 255);
        $white = ImageColorAllocate($img, 255, 0, 0);
        ImageString($img, 5, 30, 20, "Picture", $white);
        ImageString($img, 5, 45, 40, "Not", $white);
        ImageString($img, 5, 25, 60, "Available", $white);
        ImagePNG($img);
        ImageDestroy($img);
        exit();
    }
    
    $x=imageSX($bigimage);
    $y=imageSY($bigimage);        
    
    if($resize == 'no' || (($x > $y) && ($x < $img_size)) || (($y > $x) && ($y < $img_size))){

        imagejpeg($bigimage);
        exit();
    }
    
    // find the larger dimension
    if ($x>$y) {    // if it is the width then
        $dx = 0;                    // the left side of the new image
        $w = $img_size;                // the width of the new image
        $h = ($y / $x) * $img_size;    // the height of the new image
        $dy = 0;                    // the top of the new image
    } else {    // if the height is larger then
        $dy = 0;                    // the top of the new image
        $h = $img_size;                // the height of the new image
        $w = ($x / $y) * $img_size;    // the width of the new image
        $dx = 0;    // the left edgeof the new image
    }
    
    $tnimage = ImageCreate($w, $h);    

    ImageCreateTrueColor($w, $h);
    ImageCopyResampled($tnimage, $bigimage, $dx, $dy, 0, 0, $w, $h, $x, $y); 
        
    // copy the resized version into the thumbnal image
    //ImageCopyResized($tnimage, $bigimage, $dx, $dy, 0, 0, $w, $h, $x, $y);    

    imagejpeg($tnimage);    

    // release the memory used by the thumbnail image
    ImageDestroy($tnimage);
    
    // release the memory used by the original big image
    ImageDestroy($bigimage);
    

?>

And this is the result:



This is what it should look like:



Any ideas where i might be going wrong?
Thanks for the help

-Pointybeard