#39273 [Bgs]: imagecopyresized() not compatable with alpha channel
ID: 39273 User updated by: seth at pricepages dot org Reported By: seth at pricepages dot org Status: Bogus Bug Type: GD related Operating System: Mac 10.4 PHP Version: 5.1.6 Assigned To: pajoye New Comment: I'm American; if I'm exposed to more than one language my head explodes. ;) Yep, that image is exactly what I'm looking for. Thanks for not just ignoring me after marking the bug bogus, I've had that happen also... Previous Comments: [2006-10-28 15:14:41] [EMAIL PROTECTED] Sorry for my bad wording (images "speak" better), but we are getting somewhere, finally. We were talking of two different problems. I was talking about a common misunderstanding and you about a more specific problem. Thanks to have insisted and nice catch :) Check this image: http://blog.thepimp.net/misc/39273_out.png Is it what you expect? [2006-10-28 14:43:21] seth at pricepages dot org translucide (French) = translucent (English) Sorry, that confused me for a bit. "Boolean transparency" means that the pixel is either fully transparent, or fully opaque. Never partially transparent. The area outside of the line is fine, it should be transparent and it is in your image. This is correct. What is suffering from "boolean transparency" are the edges of the line. For example: In your example script, one alpha value was 63, and the other was 127. In your output PNG, those values have been changed to 0 and 127. I should mention that if you are using Microsoft's Internet Explorer version 6 or less, a PNG image will display with boolean transparency due to a bug in the browser. So you won't be able to see the difference. Use FireFox. [2006-10-28 14:19:46] [EMAIL PROTECTED] Pardon? What is a boolean transparency? Please understand these three things: - The transparent color is one *color*, an index for palette based image or 32bits value for truecolor images. It defines which color is used as the *background* color (like white is the background color of a white paper). - The *alpha* channel of a pixel defines how translucide the pixel has to be. It has nothing to do with the transparent color. - Your image has *no* transparent color but many pixels with various *alpha* levels. Load the result images in your favourite paint programs to see what I mean. The area outside the line is translucide, it is due to the alpha channel. [2006-10-28 14:11:56] seth at pricepages dot org But that has one of the bugs that I pointed out: boolean transparency. The original doesn't have that problem. [2006-10-28 14:04:59] [EMAIL PROTECTED] Use the code I just gave you, it does create the resized version (by copying): http://blog.thepimp.net/misc/39273_out.png 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/39273 -- Edit this bug report at http://bugs.php.net/?id=39273&edit=1
#39273 [Bgs]: imagecopyresized() not compatable with alpha channel
ID: 39273 Updated by: [EMAIL PROTECTED] Reported By: seth at pricepages dot org Status: Bogus Bug Type: GD related Operating System: Mac 10.4 PHP Version: 5.1.6 Assigned To: pajoye New Comment: Sorry for my bad wording (images "speak" better), but we are getting somewhere, finally. We were talking of two different problems. I was talking about a common misunderstanding and you about a more specific problem. Thanks to have insisted and nice catch :) Check this image: http://blog.thepimp.net/misc/39273_out.png Is it what you expect? Previous Comments: [2006-10-28 14:43:21] seth at pricepages dot org translucide (French) = translucent (English) Sorry, that confused me for a bit. "Boolean transparency" means that the pixel is either fully transparent, or fully opaque. Never partially transparent. The area outside of the line is fine, it should be transparent and it is in your image. This is correct. What is suffering from "boolean transparency" are the edges of the line. For example: In your example script, one alpha value was 63, and the other was 127. In your output PNG, those values have been changed to 0 and 127. I should mention that if you are using Microsoft's Internet Explorer version 6 or less, a PNG image will display with boolean transparency due to a bug in the browser. So you won't be able to see the difference. Use FireFox. [2006-10-28 14:19:46] [EMAIL PROTECTED] Pardon? What is a boolean transparency? Please understand these three things: - The transparent color is one *color*, an index for palette based image or 32bits value for truecolor images. It defines which color is used as the *background* color (like white is the background color of a white paper). - The *alpha* channel of a pixel defines how translucide the pixel has to be. It has nothing to do with the transparent color. - Your image has *no* transparent color but many pixels with various *alpha* levels. Load the result images in your favourite paint programs to see what I mean. The area outside the line is translucide, it is due to the alpha channel. [2006-10-28 14:11:56] seth at pricepages dot org But that has one of the bugs that I pointed out: boolean transparency. The original doesn't have that problem. [2006-10-28 14:04:59] [EMAIL PROTECTED] Use the code I just gave you, it does create the resized version (by copying): http://blog.thepimp.net/misc/39273_out.png [2006-10-28 13:15:45] seth at pricepages dot org I ran your code before I posted my last comment, but I still don't know what you are implying. The results are exactly as I expect them to be. If this bug is bogus, please tell me how I can create an enlarged version of test.png? It isn't possible without applying a fix. 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/39273 -- Edit this bug report at http://bugs.php.net/?id=39273&edit=1
#39273 [Bgs]: imagecopyresized() not compatable with alpha channel
ID: 39273 User updated by: seth at pricepages dot org Reported By: seth at pricepages dot org Status: Bogus Bug Type: GD related Operating System: Mac 10.4 PHP Version: 5.1.6 Assigned To: pajoye New Comment: translucide (French) = translucent (English) Sorry, that confused me for a bit. "Boolean transparency" means that the pixel is either fully transparent, or fully opaque. Never partially transparent. The area outside of the line is fine, it should be transparent and it is in your image. This is correct. What is suffering from "boolean transparency" are the edges of the line. For example: In your example script, one alpha value was 63, and the other was 127. In your output PNG, those values have been changed to 0 and 127. I should mention that if you are using Microsoft's Internet Explorer version 6 or less, a PNG image will display with boolean transparency due to a bug in the browser. So you won't be able to see the difference. Use FireFox. Previous Comments: [2006-10-28 14:19:46] [EMAIL PROTECTED] Pardon? What is a boolean transparency? Please understand these three things: - The transparent color is one *color*, an index for palette based image or 32bits value for truecolor images. It defines which color is used as the *background* color (like white is the background color of a white paper). - The *alpha* channel of a pixel defines how translucide the pixel has to be. It has nothing to do with the transparent color. - Your image has *no* transparent color but many pixels with various *alpha* levels. Load the result images in your favourite paint programs to see what I mean. The area outside the line is translucide, it is due to the alpha channel. [2006-10-28 14:11:56] seth at pricepages dot org But that has one of the bugs that I pointed out: boolean transparency. The original doesn't have that problem. [2006-10-28 14:04:59] [EMAIL PROTECTED] Use the code I just gave you, it does create the resized version (by copying): http://blog.thepimp.net/misc/39273_out.png [2006-10-28 13:15:45] seth at pricepages dot org I ran your code before I posted my last comment, but I still don't know what you are implying. The results are exactly as I expect them to be. If this bug is bogus, please tell me how I can create an enlarged version of test.png? It isn't possible without applying a fix. [2006-10-28 10:49:54] [EMAIL PROTECTED] "I am aware that the image is fully black, except for variations in alpha. That is why this is a bug related to the alpha channel and not any other." You are not aware that your image is *NOT* fully black. Background color (the transparent color) is not the same than a color with a ALPHA component. Please run the code I gave you, read the results (like the values of the channels in these two pixels, or any other). 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/39273 -- Edit this bug report at http://bugs.php.net/?id=39273&edit=1
#39273 [Bgs]: imagecopyresized() not compatable with alpha channel
ID: 39273 Updated by: [EMAIL PROTECTED] Reported By: seth at pricepages dot org Status: Bogus Bug Type: GD related Operating System: Mac 10.4 PHP Version: 5.1.6 Assigned To: pajoye New Comment: Pardon? What is a boolean transparency? Please understand these three things: - The transparent color is one *color*, an index for palette based image or 32bits value for truecolor images. It defines which color is used as the *background* color (like white is the background color of a white paper). - The *alpha* channel of a pixel defines how translucide the pixel has to be. It has nothing to do with the transparent color. - Your image has *no* transparent color but many pixels with various *alpha* levels. Load the result images in your favourite paint programs to see what I mean. The area outside the line is translucide, it is due to the alpha channel. Previous Comments: [2006-10-28 14:11:56] seth at pricepages dot org But that has one of the bugs that I pointed out: boolean transparency. The original doesn't have that problem. [2006-10-28 14:04:59] [EMAIL PROTECTED] Use the code I just gave you, it does create the resized version (by copying): http://blog.thepimp.net/misc/39273_out.png [2006-10-28 13:15:45] seth at pricepages dot org I ran your code before I posted my last comment, but I still don't know what you are implying. The results are exactly as I expect them to be. If this bug is bogus, please tell me how I can create an enlarged version of test.png? It isn't possible without applying a fix. [2006-10-28 10:49:54] [EMAIL PROTECTED] "I am aware that the image is fully black, except for variations in alpha. That is why this is a bug related to the alpha channel and not any other." You are not aware that your image is *NOT* fully black. Background color (the transparent color) is not the same than a color with a ALPHA component. Please run the code I gave you, read the results (like the values of the channels in these two pixels, or any other). [2006-10-27 17:22:07] seth at pricepages dot org I am aware that the image is fully black, except for variations in alpha. That is why this is a bug related to the alpha channel and not any other. Well, I went in and fixed it myself. The problem was in the function gdImageGetTrueColorPixel(). It assumed that palette images always have binary transparency, with a correct value in im->transparent. Because my source image didn't have a correct value in im->transparent, it was always marked as opaque. This line: return gdTrueColorAlpha(im->red[p], im->green[p], im->blue [p], (im->transparent == p) ? gdAlphaTransparent : gdAlphaOpaque); Needs to be changed to: return gdTrueColorAlpha(im->red[p], im->green[p], im->blue [p], (im->transparent == p) ? gdAlphaTransparent : im->alpha [p]); Making this patch also fixes the same bug in imagecopyresampled(), and who knows what else. Although, I would recommend using gdTrueColorAlpha() at the appropriate point(s) in gdImageCopyResized() instead of gdImageGetTrueColorPixel(). This would eliminate an extra function call, branch, and color lookup. 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/39273 -- Edit this bug report at http://bugs.php.net/?id=39273&edit=1
#39273 [Bgs]: imagecopyresized() not compatable with alpha channel
ID: 39273 User updated by: seth at pricepages dot org Reported By: seth at pricepages dot org Status: Bogus Bug Type: GD related Operating System: Mac 10.4 PHP Version: 5.1.6 Assigned To: pajoye New Comment: But that has one of the bugs that I pointed out: boolean transparency. The original doesn't have that problem. Previous Comments: [2006-10-28 14:04:59] [EMAIL PROTECTED] Use the code I just gave you, it does create the resized version (by copying): http://blog.thepimp.net/misc/39273_out.png [2006-10-28 13:15:45] seth at pricepages dot org I ran your code before I posted my last comment, but I still don't know what you are implying. The results are exactly as I expect them to be. If this bug is bogus, please tell me how I can create an enlarged version of test.png? It isn't possible without applying a fix. [2006-10-28 10:49:54] [EMAIL PROTECTED] "I am aware that the image is fully black, except for variations in alpha. That is why this is a bug related to the alpha channel and not any other." You are not aware that your image is *NOT* fully black. Background color (the transparent color) is not the same than a color with a ALPHA component. Please run the code I gave you, read the results (like the values of the channels in these two pixels, or any other). [2006-10-27 17:22:07] seth at pricepages dot org I am aware that the image is fully black, except for variations in alpha. That is why this is a bug related to the alpha channel and not any other. Well, I went in and fixed it myself. The problem was in the function gdImageGetTrueColorPixel(). It assumed that palette images always have binary transparency, with a correct value in im->transparent. Because my source image didn't have a correct value in im->transparent, it was always marked as opaque. This line: return gdTrueColorAlpha(im->red[p], im->green[p], im->blue [p], (im->transparent == p) ? gdAlphaTransparent : gdAlphaOpaque); Needs to be changed to: return gdTrueColorAlpha(im->red[p], im->green[p], im->blue [p], (im->transparent == p) ? gdAlphaTransparent : im->alpha [p]); Making this patch also fixes the same bug in imagecopyresampled(), and who knows what else. Although, I would recommend using gdTrueColorAlpha() at the appropriate point(s) in gdImageCopyResized() instead of gdImageGetTrueColorPixel(). This would eliminate an extra function call, branch, and color lookup. [2006-10-27 14:01:12] [EMAIL PROTECTED] There is nothing wrong in imagecopyresize (or imagecopy). The problem you have is the misunderstanding of what is the background color, the alpha channel and alpha blending. Your original image has many black colors, one is transparent (what you consider as background), and the other with various transparency levels. Try the code below, it will explain you what is your image and how it works. http://bugs.php.net/39273 -- Edit this bug report at http://bugs.php.net/?id=39273&edit=1
#39273 [Bgs]: imagecopyresized() not compatable with alpha channel
ID: 39273 Updated by: [EMAIL PROTECTED] Reported By: seth at pricepages dot org Status: Bogus Bug Type: GD related Operating System: Mac 10.4 PHP Version: 5.1.6 Assigned To: pajoye New Comment: Use the code I just gave you, it does create the resized version (by copying): http://blog.thepimp.net/misc/39273_out.png Previous Comments: [2006-10-28 13:15:45] seth at pricepages dot org I ran your code before I posted my last comment, but I still don't know what you are implying. The results are exactly as I expect them to be. If this bug is bogus, please tell me how I can create an enlarged version of test.png? It isn't possible without applying a fix. [2006-10-28 10:49:54] [EMAIL PROTECTED] "I am aware that the image is fully black, except for variations in alpha. That is why this is a bug related to the alpha channel and not any other." You are not aware that your image is *NOT* fully black. Background color (the transparent color) is not the same than a color with a ALPHA component. Please run the code I gave you, read the results (like the values of the channels in these two pixels, or any other). [2006-10-27 17:22:07] seth at pricepages dot org I am aware that the image is fully black, except for variations in alpha. That is why this is a bug related to the alpha channel and not any other. Well, I went in and fixed it myself. The problem was in the function gdImageGetTrueColorPixel(). It assumed that palette images always have binary transparency, with a correct value in im->transparent. Because my source image didn't have a correct value in im->transparent, it was always marked as opaque. This line: return gdTrueColorAlpha(im->red[p], im->green[p], im->blue [p], (im->transparent == p) ? gdAlphaTransparent : gdAlphaOpaque); Needs to be changed to: return gdTrueColorAlpha(im->red[p], im->green[p], im->blue [p], (im->transparent == p) ? gdAlphaTransparent : im->alpha [p]); Making this patch also fixes the same bug in imagecopyresampled(), and who knows what else. Although, I would recommend using gdTrueColorAlpha() at the appropriate point(s) in gdImageCopyResized() instead of gdImageGetTrueColorPixel(). This would eliminate an extra function call, branch, and color lookup. [2006-10-27 14:01:12] [EMAIL PROTECTED] There is nothing wrong in imagecopyresize (or imagecopy). The problem you have is the misunderstanding of what is the background color, the alpha channel and alpha blending. Your original image has many black colors, one is transparent (what you consider as background), and the other with various transparency levels. Try the code below, it will explain you what is your image and how it works. http://snaps.php.net/php5.2-latest.tar.gz For Windows: http://snaps.php.net/win32/php5.2-win32-latest.zip 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/39273 -- Edit this bug report at http://bugs.php.net/?id=39273&edit=1
#39273 [Bgs]: imagecopyresized() not compatable with alpha channel
ID: 39273
User updated by: seth at pricepages dot org
Reported By: seth at pricepages dot org
Status: Bogus
Bug Type: GD related
Operating System: Mac 10.4
PHP Version: 5.1.6
Assigned To: pajoye
New Comment:
I ran your code before I posted my last comment, but I still
don't know what you are implying. The results are exactly as I
expect them to be.
If this bug is bogus, please tell me how I can create an
enlarged version of test.png? It isn't possible without
applying a fix.
Previous Comments:
[2006-10-28 10:49:54] [EMAIL PROTECTED]
"I am aware that the image is fully black, except for
variations in alpha. That is why this is a bug related to
the alpha channel and not any other."
You are not aware that your image is *NOT* fully black.
Background color (the transparent color) is not the same than a color
with a ALPHA component. Please run the code I gave you, read the
results (like the values of the channels in these two pixels, or any
other).
[2006-10-27 17:22:07] seth at pricepages dot org
I am aware that the image is fully black, except for
variations in alpha. That is why this is a bug related to
the alpha channel and not any other.
Well, I went in and fixed it myself. The problem was in the
function gdImageGetTrueColorPixel(). It assumed that palette
images always have binary transparency, with a correct value
in im->transparent. Because my source image didn't have a
correct value in im->transparent, it was always marked as
opaque.
This line:
return gdTrueColorAlpha(im->red[p], im->green[p], im->blue
[p], (im->transparent == p) ? gdAlphaTransparent :
gdAlphaOpaque);
Needs to be changed to:
return gdTrueColorAlpha(im->red[p], im->green[p], im->blue
[p], (im->transparent == p) ? gdAlphaTransparent : im->alpha
[p]);
Making this patch also fixes the same bug in
imagecopyresampled(), and who knows what else.
Although, I would recommend using gdTrueColorAlpha() at the
appropriate point(s) in gdImageCopyResized() instead of
gdImageGetTrueColorPixel(). This would eliminate an extra
function call, branch, and color lookup.
[2006-10-27 14:01:12] [EMAIL PROTECTED]
There is nothing wrong in imagecopyresize (or imagecopy).
The problem you have is the misunderstanding of what is the background
color, the alpha channel and alpha blending.
Your original image has many black colors, one is transparent (what you
consider as background), and the other with various transparency
levels.
Try the code below, it will explain you what is your image and how it
works.
http://snaps.php.net/php5.2-latest.tar.gz
For Windows:
http://snaps.php.net/win32/php5.2-win32-latest.zip
[2006-10-27 04:17:23] seth at pricepages dot org
Description:
imagecopyresampled() should be copying the alpha channel, but
it doesn't seem to be doing so. This is a palette based source
image being copied to a true color image.
If you use imagecopy() instead, the image copies as expected
(mostly).
Reproduce code:
---
http://leopold.sage.wisc.edu/test.png');
$width = 300;
$height = 300;
$srcW = imagesx($small);
$srcH = imagesy($small);
$img = imagecreatetruecolor($width, $height);
//Make a transparent canvas
$trans = imagecolorresolve($img,255,255,255);
imagecolortransparent($img, $trans);
imagealphablending($img, false);
imagefilledrectangle( $img,
0, 0,
$width, $height,
$trans);
//This shouldn't *need* to be on, but it does
imagealphablending($img, true);
//One of these works, the other doesn't
//imagecopy($img, $small, 0,0, 0,0, $srcW, $srcH);
imagecopyresized($img, $small, 0,0, 0,0, $width, $height, $srcW,
$srcH);
header('Content-Type: image/png');
imagepng($img);
?>
Expected result:
An enlarged, pixellated, mostly transparent, image.
Actual result:
--
A black, opaque, image.
--
Edit this bug report at http://bugs.php.net/?id=39273&edit=1
