[csswg-drafts] [filter-effects-1] Sepia definition should allow for higher quality implementations (#5026)

litherum has just created a new issue for https://github.com/w3c/csswg-drafts:

== [filter-effects-1] Sepia definition should allow for higher quality implementations ==
The [definition](https://www.w3.org/TR/filter-effects-1/#sepiaEquivalent) for `sepia` indicates that its definition is a simple matrix transform with hardcoded values from the spec.

However, macOS and iOS platforms come with a [built-in implementation of a sepia filter](https://developer.apple.com/library/archive/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html#//apple_ref/doc/filter/ci/CISepiaTone) which is results in a higher-quality result than the simple matrix transform listed in the spec.

(Left is the matrix transform listed in the spec; right is the platform built-in filter using Core Image)
<img width="1060" alt="Screen Shot 2020-04-29 at 12 56 03 PM" src="https://user-images.githubusercontent.com/918903/80642322-2522a900-8a1b-11ea-89c5-0d004af3a653.png">

The OS implementation does not simply consist of a matrix transformation; there is more complicated math involved in the kernel. Therefore, I'd like to propose broadening the definition of the sepia filter in the spec to allow for higher-quality implementations, without exactly specifying what calculations the implementations may perform.

In particular, for the specific example of sepia, the benefit of a higher quality implementation seems to outweigh the benefit of perfect consistency between browsers.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5026 using your GitHub account

Received on Wednesday, 29 April 2020 20:32:47 UTC