#40158 [Fbk-Opn]: Artifact left on transparent pngs using image filters
ID: 40158 User updated by: henus at mail dot ru Reported By: henus at mail dot ru -Status: Feedback +Status: Open Bug Type: GD related Operating System: Windows XP PHP Version: 5.2.0 Assigned To: pajoye New Comment: Yes, the is global problem with alphablending in libgd\gd.c but about imagealphablending($mask, false); // Important!: i absolutely should not care about ebabling\disabling imagealphablending before imagefilter, because of function shoud colorize image by new values of red,gree,blue (!!!there is no alpha in parameters) if IMG_FILTER_COLORIZE will have in parameters alpha, if alphablending enable, value of alpha should allow for calculation of new color values (in gdImageColor it will before new_pxl = gdImageColorAllocateAlpha(src, (int)r, (int)g, (int)b, a);) and gdImageSetPixel shoul with disabled alphablending. otherwise function work like merging of two images with alphablending. where: first image - source image from function parameters. second image - correct colorized copy of source image. it is not logically. it is incorrect. another bug in imagefill: this function not only fill image, it is also disable alphablending. php example: ? /* first colorizing */ $im1=imagecreatetruecolor(1,1); imagealphablending($im1, TRUE); $c01=imagecolorallocatealpha($im1,255,0,0,63); imagefill($im1,0,0,$c01); $c01=imagecolorsforindex($im1,imagecolorat($im1,0,0)); imagefilter($im1, IMG_FILTER_COLORIZE, -255, 255, 0); $c1=imagecolorsforindex($im1,imagecolorat($im1,0,0)); /* second colorizing */ $im2=imagecreatetruecolor(1,1); imagealphablending($im2, TRUE); $c02=imagecolorallocatealpha($im2,255,0,0,63); imagefill($im2,0,0,$c02); $c02=imagecolorsforindex($im1,imagecolorat($im1,0,0)); /* att!!! after imagefill another enabling alphablending */ imagealphablending($im2, TRUE); imagefilter($im2, IMG_FILTER_COLORIZE, -255, 255, 0); $c2=imagecolorsforindex($im2,imagecolorat($im2,0,0)); printbrbefore 1 - ; print_r($c01); printbrafter 1 - ; print_r($c1); printbrbrbefore 2 - ; print_r($c02); printbrafter 2 - ; print_r($c2); ? results: before 1- Array ( [red] = 255 [green] = 0 [blue] = 0 [alpha] = 63 ) after 1 - Array ( [red] = 0 [green] = 255 [blue] = 0 [alpha] = 63 ) before 2- Array ( [red] = 0 [green] = 255 [blue] = 0 [alpha] = 63 ) after 2 - Array ( [red] = 126 [green] = 128 [blue] = 0 [alpha] = 31 ) where: after 1 - correct result of IMG_FILTER_COLORIZE, because of imagefill disable alphablending after 2 - incorrect result of IMG_FILTER_COLORIZE, because of after imagefill i manually enable alphablending disabling alphablending in code it is good solutions for gdImageColor, but after it is necessary to restore old value of alphaBlendingFlag. Previous Comments: [2007-01-18 19:54:09] [EMAIL PROTECTED] pixel from edge with coord (95,11) have wrong color. red-98 green-98 blue-164 (why is red0 and green0 ? after substracting 255???) (should be red-0 green-0 blue-102) It is blended over the destination pixel. You have to disable alpha blending *before* the imagefilter call. This image: http://blog.thepimp.net/misc/bug40158_black_filtered_mask.png shows exactly what you are trying to do (blue, black or purple, it really does not matter), the script being: $mask=imagecreatefrompng(40158.png); imagealphablending($mask, false); // Important! imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, -255); // save alpha, so we see its value imagesavealpha($mask, true); imagepng($mask,mask1.png); Using your last example, the resulting image is like your result_correct3.png. [2007-01-18 19:37:49] henus at mail dot ru it`s not solve my problem :( first - about blue color - look at my submission from [18 Jan 11:03am UTC] if use imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, -255); the result is http://www.fort-ross.ru/henus/gd/result_incorrect.png with legibly visible artefacts. second - image http://blog.thepimp.net/misc/bug40158_result.png also has artefacts at the adges... pixel from edge with coord (95,11) have wrong color red-98 green-98 blue-164 (why is red0 and green0 ? after substracting 255???) (should be red-0 green-0 blue-102) third - look at my submission from [18 Jan 5:56pm UTC] why is 255-255=126 one more demo - using imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, 0); mask - http://fort-ross.ru/henus/gd/mask3.png incorrect image - http://fort-ross.ru/henus/gd/result_incorrect3.png correct image - http://fort-ross.ru/henus/gd/result_correct3.png [2007-01-18 18:51:59] [EMAIL PROTECTED] (rgba(255,0,0,xxx)) should have been (rgba(0,0,255,xxx)) but you noticed it :)
#40158 [Fbk-Opn]: Artifact left on transparent pngs using image filters
ID: 40158
User updated by: henus at mail dot ru
Reported By: henus at mail dot ru
-Status: Feedback
+Status: Open
Bug Type: GD related
Operating System: Windows XP
PHP Version: 5.2.0
Assigned To: pajoye
New Comment:
i create black image and overlay it by colorized
white-truecolor-png24-image ( http://fort-ross.ru/henus/gd/mask.png )
the result of colorize like:
imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, -255);
is image:
http://www.fort-ross.ru/henus/gd/result_incorrect.png
which contain artefacts...
also, the result of such script (
http://fort-ross.ru/henus/gd/demo2.phps )
is:
is truecolor - 1
before - Array ( [red] = 255 [green] = 255 [blue] = 255 [alpha] =
63 )
wrong result, using filter - Array ( [red] = 126 [green] = 126 [blue]
= 126 [alpha] = 31 )
wrong result, using imagecolorallocatealpha and imagesetpixel - Array (
[red] = 126 [green] = 126 [blue] = 126 [alpha] = 31 )
correct result, using imagefill, imagecolorallocatealpha and
imagesetpixel - Array ( [red] = 0 [green] = 0 [blue] = 0 [alpha] =
63 )
I.e.
colorizing pixel ( [red] = 255 [green] = 255 [blue] = 255 [alpha] =
63 ) to black
should be with ( [red] = 0 [green] = 0 [blue] = 0 [alpha] = 63 ),
not ( [red] = 126 [green] = 126 [blue] = 126 [alpha] = 31 )
Previous Comments:
[2007-01-18 15:22:49] [EMAIL PROTECTED]
Can you provide an image to show what you expect?
I did not check your script but having an image will help to really
understand what you are trying to achieve.
By the way, filters work only with truecolor images, allocate will
never fail.
[2007-01-18 14:26:28] [EMAIL PROTECTED]
...should be without alpha...
Could you plz elaborate?
A unified diff would explain it much better, btw.
[2007-01-18 14:23:38] henus at mail dot ru
php-5.2.0\ext\gd\libgd\gd.c
Lines 3682-3685:
new_pxl = gdImageColorAllocateAlpha(src, (int)r, (int)g, (int)b, a);
if (new_pxl == -1) {
new_pxl = gdImageColorClosestAlpha(src, (int)r, (int)g, (int)b, a);
}
should be without alpha...
[2007-01-18 11:03:15] henus at mail dot ru
My mistake...
correct 12 line in Reproduce code:
imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, -255);
[2007-01-18 10:40:42] henus at mail dot ru
Description:
After using imagefilter (IMG_FILTER_COLORIZE) on transparent png image
the result color of translucent pixels is wrong.
I.e. the edge of non-transparent part of image, which contain
translucent antialiasing area - wrong colored.
Reproduce code:
---
?
$mask=imagecreatefrompng(mask.png); //
http://fort-ross.ru/henus/gd/mask.png (mask for colorize, contain
translucent)
$imagewidth=imagesx($mask);
$imageheight=imagesy($mask);
$imagemain=imagecreatetruecolor($imagewidth,$imageheight);
imagealphablending($mask, TRUE);
imagealphablending($imagemain, TRUE);
$color=imagecolorallocate($imagemain, 0, 0, 0);
imagefill($imagemain, 0, 0, $color);
imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, 0);
imagecopy($imagemain, $mask, 0, 0, 0, 0, $imagewidth, $imageheight);
imagepng($imagemain,result_incorrect.png); //
http://www.fort-ross.ru/henus/gd/result_incorrect.png
imagedestroy($mask);
imagedestroy($imagemain);
?
Expected result:
The result image - absolutely black square
Actual result:
--
The result image - black square with gray line (on the edge of mask
image)
--
Edit this bug report at http://bugs.php.net/?id=40158edit=1
#40158 [Fbk-Opn]: Artifact left on transparent pngs using image filters
ID: 40158
User updated by: henus at mail dot ru
Reported By: henus at mail dot ru
-Status: Feedback
+Status: Open
Bug Type: GD related
Operating System: Windows XP
PHP Version: 5.2.0
Assigned To: pajoye
New Comment:
it`s not solve my problem :(
first -
about blue color - look at my submission from
[18 Jan 11:03am UTC]
if use
imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, -255);
the result is
http://www.fort-ross.ru/henus/gd/result_incorrect.png
with legibly visible artefacts.
second -
image
http://blog.thepimp.net/misc/bug40158_result.png
also has artefacts at the adges...
pixel from edge with coord (95,11) have wrong color
red-98
green-98
blue-164
(why is red0 and green0 ? after substracting 255???)
(should be
red-0
green-0
blue-102)
third -
look at my submission from [18 Jan 5:56pm UTC]
why is 255-255=126
one more demo -
using
imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, 0);
mask - http://fort-ross.ru/henus/gd/mask3.png
incorrect image - http://fort-ross.ru/henus/gd/result_incorrect3.png
correct image - http://fort-ross.ru/henus/gd/result_correct3.png
Previous Comments:
[2007-01-18 18:51:59] [EMAIL PROTECTED]
(rgba(255,0,0,xxx)) should have been (rgba(0,0,255,xxx)) but you
noticed it :)
[2007-01-18 18:51:04] [EMAIL PROTECTED]
An absolute black image is not what you should expect.
imagefilter($mask, IMG_FILTER_COLORIZE, -255, -255, 0); will replace
the white color with blue (you remove all components but the blue):
http://blog.thepimp.net/misc/bug40158_filtered_mask.png
imagecopy($imagemain, $mask, 0, 0, 0, 0, $imagewidth, $imageheight);
will copy it over the $imagemain, the border of the quadrant will be
blended over black:
http://blog.thepimp.net/misc/bug40158_result.png
Each pixel in your circle are rgb(255,255,255) with some alpha value in
the edges (and only in the edges). You are substracting 255 to the R and
G component, the result is blue.
Now, take a look at this image:
http://blog.thepimp.net/misc/bug40158_correct_filtered_mask.png
It is what you are expecting (if I understand correctly your problem).
The edges of the circle have a blue color with various alpha values
(rgba(255,0,0,xxx)). You can reproduce it by disabling the alpha
blending mode in the mask image (imagealphablending($mask, false); ).
The alpha component will be kept and stored in the image instead of
being used as a blending value.
Let me know if that solves your problem.
By the way, COLORIZE uses gdImageColor. The lines you are referring to
are in the contrast function.
[2007-01-18 18:32:16] henus at mail dot ru
i expect absolutely black image like
http://www.fort-ross.ru/henus/gd/result_correct.png
instead of
http://www.fort-ross.ru/henus/gd/result_incorrect.png
i use colorizing by black for clearness.
[2007-01-18 18:11:31] henus at mail dot ru
correction fo my previous post about
php-5.2.0\ext\gd\libgd\gd.c
Lines 3682-3688:
new_pxl = gdImageColorAllocateAlpha(src, (int)r, (int)g, (int)b, a);
if (new_pxl == -1) {
new_pxl = gdImageColorClosestAlpha(src, (int)r, (int)g, (int)b, a);
}
if ((y = 0) (y src-sy)) {
gdImageSetPixel (src, x, y, new_pxl);
in gdImageSetPixel src should be absolutely transparent, with
alpha=127
differently it mix colors.
[2007-01-18 18:09:31] [EMAIL PROTECTED]
Please provide an *image* showing what you expect.
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/40158
--
Edit this bug report at http://bugs.php.net/?id=40158edit=1
