50464 - PNG images /w transparency do not display correctly in 256 colour mode.

Status: RESOLVED WORKSFORME

(Core :: Graphics: ImageLib, defect, P3)

Description

[david.mcbride]

From Bugzilla Helper:
User-Agent: Mozilla/4.74 [en] (WinNT; U)
BuildID:    2000082608

Images embedded in web pages which contain alpha channels (with .PNGs, perhaps 
other file formats) do not display correctly:  the transparency mask is set 
correctly (ie the areas which are supposed to be transparent are); however the 
image itself is squashed horizontally and repeated three times.  Also, the 
colours of the squashed image are incorrect - the first instance of the image 
contains only the red channel (ie no green or blue), the second repetition of 
the image contains the green channel, the the third repetition contains only 
blue.

Reproducible: Always
Steps to Reproduce:
1) Setup NT to use 256 colour mode
2) Go to http://www.doc.ic.ac.uk/~dwm99 in mozilla.
3) scroll down to image of Tux - it displays incorrectly.

Actual Results:  The .png images with transparency information are on the page 
display incorrectly as described in 'Description'.  					

Expected Results:  The non-transparent parts of the image should contain either 
the correct colour for each pixel or, where not possible using the current 
palette, an image with the colours dithered appropriately.				

The machine this has been tested on is a Intel Pentium box running NT4 SP5.

Comment 1

[Peter Howkins]

Also see this on build 2000091212 on windows 98, in 256 colours. I also see this 
when the image is loaded as a direct url.
http://www.doc.ic.ac.uk/~dwm99/Resources/Penguin.png
This fails as well, not just embedded in pages.

Comment 2

[Paul Wyskoczka]

Updating QA Contact

Comment 3

[pnunn]

All pnunn bugs reassigned to Pav, who is taking over
the imglib.

Comment 4

[Daniel Steinberger]

the problems described in this bug work for me in 2002022103 - it's been a long
while for this bug without progress.. almost a year. and over a year since
[e-mail] confirmed the problem. i checked it out, but what you
describe does not happen for me.
nevertheless, this bug falls under the criteria for bug 121230, this image gets
scrambled, too.

so, i will just mark this bug WORKSFORME, since i guess it's fixed already.
complain or jump over to bug 121230 if there's anything wrong with this.