Bug 231653

Summary:

[TextureMapper] large blur filter doesn't look smooth

Product:

WebKit

Reporter:

Fujii Hironori <Hironori.Fujii>

Component:

Platform

Assignee:

Nobody <webkit-unassigned>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

aki.develop8128, cgarcia, kdwkleung, smoley, webkit-bug-importer

Priority:

Keywords:

InRadar

Version:

WebKit Nightly Build

Hardware:

Unspecified

OS:

Unspecified

See Also:

https://bugs.webkit.org/show_bug.cgi?id=87695

Bug Depends on:

261022, 261101, 261102

Bug Blocks:

Attachments:

Description	Flags
test case	none

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!