Req #66887 [Fbk]: imagescale - poor quality of scaled image

Edit report at https://bugs.php.net/bug.php?id=66887&edit=1 ID: 66887 Updated by: pajoye@php.net Reported by: mruz at poczta dot onet dot pl Summary: imagescale - poor quality of scaled image Status: Feedback Type: Feature/Change Request Package: GD related Operating System: openSUSE 13.1 PHP Version: 5.5.10 Block user comment: N Private report: N New Comment: Please ignore the background call. It is totally unrelated to this problem. JPEG does not have alpha, so could you please using only the scale function and compare the results? See http://www.php.net/imagesetinterpolation for the different algorithms available. Previous Comments: ------------------------------------------------------------------------ [2014-03-12 10:02:36] mruz at poczta dot onet dot pl I resized to 600x400: http://mruz.pl/test/test1.jpg (imagecopyresized) http://mruz.pl/test/test2.jpg (imagescale) http://mruz.pl/test/test.jpg (oryginal) If I apply white background after imagescale(): imagecolorallocatealpha($background, r, g, b, $opacity); imagealphablending($background, true); imagecopy($background, $img, 0, 0, 0, 0, $width, $height) is much worse.. http://mruz.pl/test/test3.jpg (background after imagescale) ------------------------------------------------------------------------ [2014-03-12 09:20:03] pajoye@php.net imagescale has many different algorithms, some are good for downscaling other for upscaling. Performance differs too from one to another. Try other algorithms and use the right one depending on what you want to do. Also having an example image may help to answer. Can you post a link to one? ------------------------------------------------------------------------ [2014-03-12 08:28:09] mruz at poczta dot onet dot pl Or even http://www.php.net/function.imagecopyresized ------------------------------------------------------------------------ [2014-03-12 08:23:10] mruz at poczta dot onet dot pl Description: ------------ Is it intended behavior that the quality of http://www.php.net/function.imagescale is much worse than http://www.php.net/function.imagecopyresampled ? I'm using PHP 5.5.9, but see in the PHP 5.5.10 changelog nothing on this issuse was changed. Test script: --------------- $oryginal = imagecreatefromjpeg('test.jpg'); $img = imagecreatetruecolor(300, 200); imagecopyresized($img, $oryginal, 0, 0, 0, 0, 300, 200, 600, 400); imagejpeg($img, 'test1.jpg', 90); echo '<img src="test1.jpg" /><br />'; $img = imagescale($oryginal, 300, 200); imagejpeg($img, 'test2.jpg', 90); echo '<img src="test2.jpg" /><br />'; ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=66887&edit=1