I try to use PHP GD library to resize image to thumbnail size, however I found the small converted image has bad quality(distorted color), how can I improve the image quality by using PHP GD library:

PHP Syntax (Toggle Plain Text)

$first=imagecreatefromjpeg($uploadfile); 
define(MAX_WIDTH, 180);
define(MAX_HEIGHT, 135);
$width = imagesx($first);
$height = imagesy($first);
$scale = min(MAX_WIDTH/$width, MAX_HEIGHT/$height);
$new_width = floor($scale*$width);
$new_height = floor($scale*$height);
$second=imagecreate($new_width, $new_height);
imagecopyresized($second,$first,0,0,0,0,$new_width,$new_height,$width,$height);
 imagejpeg($second,$v_thumbnailfile);

$first=imagecreatefromjpeg($uploadfile); define(MAX_WIDTH, 180); define(MAX_HEIGHT, 135); $width = imagesx($first); $height = imagesy($first); $scale = min(MAX_WIDTH/$width, MAX_HEIGHT/$height); $new_width = floor($scale*$width); $new_height = floor($scale*$height); $second=imagecreate($new_width, $new_height); imagecopyresized($second,$first,0,0,0,0,$new_width,$new_height,$width,$height); imagejpeg($second,$v_thumbnailfile);

Thanks for any response.