526608 - Moiré pattern in resized image

Status: VERIFIED WORKSFORME

(Core :: Graphics, defect)

Description

[Xuân Baldauf]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.23) Gecko/20090410 SUSE/1.1.18-0.1.1 SeaMonkey/1.1.18 Mnenhy/0.7.6.666
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.23) Gecko/20090410 SUSE/1.1.18-0.1.1 SeaMonkey/1.1.18 Mnenhy/0.7.6.666

It looks like the image scaler does not cater for moiré-patterns, while it possibly should.

Reproducible: Always

Steps to Reproduce:
1. Go to http://de.wikipedia.org/w/index.php?title=Wechselwirkende_Galaxien&oldid=66368093
2. Look at the last image in the chain of images at the right side (the image caption is "Zum Vergleich eine monospektrale Aufnahme von Stephans Quintett im Spektrum des sichtbaren Lichts"). 

Actual Results:  
This image has, as displayed, a very visible moiré pattern.


Expected Results:  
This image should not have a moiré pattern that visible.

The image (unscaled) also has a pattern, but this pattern is barely visible, not so pronounced like the scaled image.
The problem also happens in Firefox (however, to a lesser extent).

Comment 1

[Tim (fmdeveloper)]

Reduced html:

<img alt=""
src="http://upload.wikimedia.org/wikipedia/commons/3/3b/Stephans_quintet_nasa.gif"
height="208" width="210">

Displays correctly in IE8 on Vista

Removing height and width parameters makes effect go away in FF. Scaling issue?

<img alt=""
src="http://upload.wikimedia.org/wikipedia/commons/3/3b/Stephans_quintet_nasa.gif">

Comment 2

[:aceman]

Attachment: testcase

I can see it too, however it is possible the effect is simply a coincidence, just skipping the right pixels when scaling down the low quality (8bit) gif image.

Comment 3

[Manuela Muntean [Away]]

Attachment: screenshot_Nightly_2013-07-30

The image looks the same, both using the URL and testcase provided, with : latest Nightly (build ID: 20130730030204), Chromium and Opera, on an Ubuntu 12.10 32bit machine.

Please see the attached screenshot for details.

Reporter, do you still reproduce this issue?

Comment 4

[Manuela Muntean [Away]]

Marking this Resolved WFM. Please reopen the bug if anyone can reproduce the issue.

Comment 5

[Xuân Baldauf]

Seems to work for me.