368794 - PNG Gamma Correction not handled correctly.

Status: RESOLVED INVALID

(Firefox :: General, defect)

Description

[Ben Chambers]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1

PNG files with gamma correction stored in them are not gamma corrected by Firefox.  This results in the image either being too dark or (in this case) too bright.

Reproducible: Always

Steps to Reproduce:
1. Go to the page I specified
2. Look at the second post on that page, at the preview image.
3. Click on the preview to see the full image.
Actual Results:  
When viewing the full image, it appears extremely bright and washed out.

Expected Results:  
The image contains gamma information which Firefox should use to adjust the brightness.  The colors should appear as they do in the preview image (which contains no gamma correction information).

Many programs ignore gamma correction in PNG files, and blame the picture authors for the images looking wrong on various systems.  This is sloppy programming.  If gamma correction were not present, not handling it would be acceptable.

However, when the gamma information is present in a file, it should be accounted for.  Images containing this gamma correction should be adjusted accordingly.  Although doing so will probably break many existing web pages, it will break them in the same way that correct support of CSS breaks web pages designed for Internet Explorer.  That is, the web pages are already broken, and Firefox should behave appropriately regardless.

Since so much of the Web is imagery, I consider the lack of correct support for one of the most common image formats to be a bug in a major feature.

Comment 2

[Glenn Randers-Pehrson]

It's not a dupe.  The large image contains an incorrect gamma value (2.2 instead of 1/2.2) and Gecko is correctly processing it.