1840447 - Noticeable banding on animated CSS gradient in Firefox, not in Chrome/Safari

Status: RESOLVED DUPLICATE of bug 627771

(Core :: Graphics, defect, P3)

Description

[Thomas Wisniewski [:twisniewski]]

Attachment: testcase.html

The attached testcase exhibits noticable color banding which doesn't appear to be OS-dependent. It was reduced from a Steam page, as reported on webcompat.com.

Comment 1

[Bob Hood [:bhood]]

Not as pronounced, but I see banding in Edge as well with the test case, especially at the hard-transition between colors.

FFx Release 114.0.2 (SW/WR) and Nightly 116.0a1 (WR) displays this harsh banding equally, so it doesn't appear to be related to hardware acceleration (or the lack thereof).

Comment 2

[Glenn Watson [:gw]]

We did previously have an existing gradient dithering implementation, however it was disabled in order to ship DirectComposition some time ago. The details are subtle but the old dithering implementation would cause unpredictable fuzziness failures due to where DC selects tiles within the virtual surface atlas. We should reimplement gradient dithering in a way that isn't affected by this.