0003642: bug in php causes imagecopyresampled to produce artifacts in images

ID	Project	Category	View Status	Date Submitted	Last Update

0003642	OXID eShop (all versions)	4.11. Image handling	public	2012-02-28 16:02	2018-11-12 14:27

Reporter	tjungcl
Priority	normal	Severity	major	Reproducibility	always
Status	acknowledged	Resolution	open
Product Version	4.5.8 revision 42471
Target Version		Fixed in Version

Summary	0003642: bug in php causes imagecopyresampled to produce artifacts in images
Description	there is a php bug https://bugs.php.net/bug.php?id=41820 that is not fixed for nearly five years now. it occures not on every machine (on ours it does, of course...) but if you have it, its most annoying: --> pictures with white backgrounds (as most shops use) have no longer a white background, but one that is striped in #FFFFFF and #FEFEFE. My own eye-sight wasnt sharp enough to notice this, but several of our designes and photographs did, so it cant be argumented away... I did not find a workaround for this with gd2, but i tried imagicks resizing function thumbnailImage() and that solved the problem. (I define resizeJpeg() in my functions.php). => its solved for me now, but you should consider to check for the lib imagick and use it if present.
Tags	Image Conversion

Theme	Not defined
Browser	All
PHP Version	Not defined
Database Version	Not defined

tjungcl 2012-02-28 16:55 reporter	stripes.jpg (4,721 bytes) stripes.jpg (4,721 bytes)

tjungcl 2012-02-28 16:55 reporter	stripes_vis.jpg (9,996 bytes) stripes_vis.jpg (9,996 bytes)

tjungcl 2012-02-28 16:57 reporter ~0005827	I added a example image, where you see the effect. This image is copied from the webshop as result of imagecopyresampled(). In the second image the contrast is raised and the brightness reduced to visualize it better.

tjungcl 2012-03-02 09:47 reporter	imagick.jpg (2,533 bytes) imagick.jpg (2,533 bytes)

tjungcl 2012-03-02 09:47 reporter	imagick_vis.jpg (3,597 bytes) imagick_vis.jpg (3,597 bytes)

tjungcl 2012-03-02 09:49 reporter ~0005863	added the same image, this time scaled down with imagemagick instead. Quality setting in imagemagick is 90% (in gd2 95%), because base quality in imagick is generally better.

dainius.bigelis 2012-03-02 10:22 reporter ~0005865	@Developers: please check if we can use this imagick lib.