Re: Pre-meeting Thoughts on HDR Canvas

On 2021-01-27 18:32, Justin Novosad wrote:
> The CSS and SVG specifications do not explicitly address the issue of 
> gamma-correct blending, but the examples in the CSS spec suggest doing 
> things the "wrong" way, which ignores gamma correctness.

The SVG specification explicitly says that filer operations are in 
linear-light sRGB by default (with an option to change to sRGB, where 
speed is more important than getting the right result); and that all 
other operations are (sadly) in gamma-encoded sRGB by default (with an 
opt-in for linear-light sRGB).

The CSS Compositing specification, sadly, requires operations in 
gamma-encoded sRGB. This choice was primarily driven by backwards 
compatibility with existing content; and secondarily with compatibility 
of blend modes, as popularized in Adobe Photoshop, which are also 
computed in gamma-encoded RGB spaces.

CSS Compositing thus needs to add an opt-in for linear-light compositing.

-- 
Chris Lilley
@svgeesus
Technical Director @ W3C
W3C Strategy Team, Core Web Design
W3C Architecture & Technology Team, Core Web & Media

Received on Wednesday, 27 January 2021 17:46:18 UTC