#41820 [Opn-Asn]: Color noise in resized image when using IMAGECOPYRESAMPLED
ID: 41820 Updated by: [EMAIL PROTECTED] Reported By: richard dot gavenda at rksting dot cz -Status: Open +Status: Assigned Bug Type: GD related Operating System: Windows XP PHP Version: 5.2.3 Assigned To: pajoye Previous Comments: [2007-06-28 10:14:26] richard dot gavenda at rksting dot cz Ok, so let's close whis thread. I will wait for future versions :-) [2007-06-28 10:12:15] richard dot gavenda at rksting dot cz So there must be some sort of bug in resampling algorithm. When i resizing bitmap filled with solid color in any bitmap editor, using any aproximation (linear, bicubic, etc.) I get an image filled with exactly same solid color. With this issue I'm unable to reach one bit transparency of resized image. [2007-06-28 10:08:08] [EMAIL PROTECTED] Position of horizontal and vertical stripes is different on different machines. Yes, it is the problem with floating points value when we need a constant and precise result on different architecture. See; http://docs.sun.com/source/806-3568/ncg_goldberg.html for a good explanation about this problem. For example, your images has variation between 126 and 127 for a given channel. It may be only something like 126.4 and 126.5. I don't think I can fix it easily for this implementation (bicubic interpolation using floating points implementation). Future versions will have more filters and using less volatile precisions. [2007-06-28 10:00:33] richard dot gavenda at rksting dot cz Position of horizontal and vertical stripes is different on different machines. [2007-06-28 09:58:20] [EMAIL PROTECTED] It is what I said, a rounding issue. I'm not sure yet how to make it more portable. The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/41820 -- Edit this bug report at http://bugs.php.net/?id=41820edit=1
#41820 [Opn-Asn]: Color noise in resized image when using IMAGECOPYRESAMPLED
ID: 41820 Updated by: [EMAIL PROTECTED] Reported By: richard dot gavenda at rksting dot cz -Status: Open +Status: Assigned Bug Type: GD related Operating System: Windows XP PHP Version: 5.2.3 -Assigned To: +Assigned To: pajoye Previous Comments: [2007-06-27 10:08:39] richard dot gavenda at rksting dot cz Title correction [2007-06-27 10:07:40] richard dot gavenda at rksting dot cz Description: When resizing an image filled with solid color using imagecopyresampled, a destination image is not filled with same solid color, but with noise of two colors. I was tried this with grayscale images. Second color in noise was exactly same as source color, but with RGB channels lowered by 1. When the source image was filled with color, which had RGB channels values equal to power of 2 (0,1,2,4,8,16,32,64,128) the noise disappears. Reproduce code: --- $im = imagecreatetruecolor(1045,600); $back = imagecolorallocate($im, 100, 100, 100); imagefill($im, 0, 0, $back); $im2 = imagecreatetruecolor(383,220); imagecopyresampled($im2,$im,0,0,0,0,383,220,1045,600); imagepng($im2); Expected result: PNG file filled with color 100,100,100(RGB) Actual result: -- PNG file filled with color noise of 100,100,100(RGB) and 99,99,99(RGB) -- Edit this bug report at http://bugs.php.net/?id=41820edit=1
