Bug 231653 - [TextureMapper] large blur filter doesn't look smooth
Summary: [TextureMapper] large blur filter doesn't look smooth
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: Platform (show other bugs)
Version: WebKit Nightly Build
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords: InRadar
Depends on: 261022 261101 261102
Blocks:
  Show dependency tree / graph
 
Reported: 2021-10-12 19:02 PDT by Fujii Hironori
Modified: 2023-09-07 03:00 PDT (History)
5 users (show)

See Also:

Attachments
test case (452 bytes, text/html)
2022-02-21 15:56 PST, Fujii Hironori 		no flags Details
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Description Fujii Hironori 2021-10-12 19:02:56 PDT 
[TextureMapper] large blur filter doesn't look smooth

attachment#413757 [details]

https://speakerdeck.com/trishagee/code-review-best-practice
Comment 1 Radar WebKit Bug Importer 2021-10-19 19:03:20 PDT 
<rdar://problem/84444307>
Comment 2 Smoley 2021-11-02 17:19:27 PDT 
Thanks for filing, the attached test case and the linked page both look smooth for me on Safari Technology Preview 134. Are you seeing this issue there as well?
Comment 3 Fujii Hironori 2021-11-02 18:23:25 PDT 
TextureMapper is used only by GTK, WPE, WinCairo and PlayStation ports.
Comment 4 Fujii Hironori 2022-02-21 15:56:44 PST 
Created attachment 452789 [details]
test case
Comment 5 Fujii Hironori 2022-06-26 23:09:27 PDT 
FEGaussianBlurSoftwareApplier::boxBlurUnaccelerated is applying box-blur three times.
https://github.com/WebKit/WebKit/blob/a713d4c4e774133040e273ce5c2ec5e8ebf85e02/Source/WebCore/platform/graphics/filters/software/FEGaussianBlurSoftwareApplier.cpp#L302-L328

This is suggested by the spec:
https://drafts.fxtf.org/filter-effects/#feGaussianBlurElement

> For larger values of "s" (s >= 2.0), an approximation can be
> used: Three successive box-blurs build a piece-wise quadratic
> convolution kernel, which approximates the Gaussian kernel to
> within roughly 3%.
Comment 6 Akihiro Kiuchi 2023-09-01 00:30:52 PDT 
I will tackle this issue under mentorship of Fujii-san.
Comment 7 Fujii Hironori 2023-09-06 20:33:30 PDT 
All sub tasks have been resovled. No more remaining tasks. Closed.
Comment 8 Carlos Garcia Campos 2023-09-07 00:40:02 PDT 
Could you add a link here to the PR fixing this issue?
Comment 9 Fujii Hironori 2023-09-07 00:48:43 PDT 
https://github.com/WebKit/WebKit/pull/17419 fixed the pixelated problem.
https://github.com/WebKit/WebKit/pull/17471 is a speed up Gaussian blur filtrer.
Comment 10 Carlos Garcia Campos 2023-09-07 03:00:45 PDT 
Thanks, great job!