86079 - 8-bit interlaced PNG not showing transparency

Status: VERIFIED DUPLICATE of bug 84980

(Core :: Graphics: ImageLib, defect)

Description

[Lectos]

From Bugzilla Helper:
User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 4.0)
BuildID:    2001060703

Certain 8-bit interlaced PNG with tranparency are not showing transparency.  If 
the image is opened by itself in the window, transparency shows up like it is 
supposed to.  This is occuring with PNG images on other sites as well.   You 
can see a good example of this on the PNG test site at 
http://www.libmng.com/pub/png/pngs-img.html   The background of the 
pengbrew_160x160.png image should be transparent.  It displays as the yellowish 
color used for transparency instead of being transparent.  The rest of the PNG 
transparency tests on the page pass.   This occurs in Win ME/NT/2k so it is a 
build bug not an OS bug.

Reproducible: Always
Steps to Reproduce:
1. Load the page and look at the image of a Penguin holding a beer  
(pengbrew_160x160.png) image.


Actual Results:  The background of the image should be transparent.

Expected Results:  The background of the image shows as the yellowish color 
used for transparency layer.

Print Screen showing problem:

http://lectos.tripod.com/pngproblem1.jpg

Print Screen showing image opened in browser window (transparency seems to work 
here):

http://lectos.tripod.com/pngproblem2.jpg

Comment 1

[Lectos]

Here is another example of some 8-bit PNG images showing partial transparency:

http://lectos.tripod.com/pngproblem3.jpg

You can see it in action at http://lectos.tripod.com/htmlstuff.html

Comment 2

[[e-mail]]

Works on Linux 2001061421, Windows specific?

Comment 3

[Lectos]

I haven't tested this build on Linux but I would say that this is just a 
problem with the Windows version.

Comment 4

[Aaron Kaluszka]

*** This bug has been marked as a duplicate of 84980 ***

Comment 5

[Terri Preston]

Verified Duplicate