- From: Khushal Sagar via GitHub <sysbot+gh@w3.org>
- Date: Wed, 17 Nov 2021 23:58:30 +0000
- To: public-css-archive@w3.org
khushalsagar has just created a new issue for https://github.com/w3c/csswg-drafts: == [css-compositing-2] Add plus-lighter to mix-blend-mode == This issue proposes adding "plus-lighter" to the list of blend modes specified in the [Compositing and Blending spec](https://drafts.fxtf.org/compositing/). This blend mode is useful when cross-fading 2 elements for which all or a subset of pixels have identical color values. An example showing the problem is here : https://static-misc-3.glitch.me/composite-test/2.html. Consider 2 elements each having a pixel with value C. These 2 elements are multiplied with opacity α and (1-α) respectively and placed in an isolated group. When blending using the 'normal' blend mode, the resulting pixel value is produced by source over compositing of the 2 elements : Co = αs x Cs + αb x Cb x (1 – αs). In this example, Cs = Cb = C; αs = α; αb = (1-α), which results in the follow color : C0 = C x ( 1 - α + α^2); For α = 0.5, this would be C x 0.75 while the desired result is C x 1. The proposed "plus-lighter" blend-mode will add the source and backdrop color value : B(Cb, Cs) = min(Cb x αs + Cs x αs, 1). The backdrop is replaced by the result of this blending operation. For the example above this would result in : Co = min(C x α + C x (1 - α)) = C This issue is related to the proposal in #6464 with the problem referenced in the explainer under [cross-fading](https://github.com/WICG/shared-element-transitions/blob/main/explainer.md#cross-fading) Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/6821 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Wednesday, 17 November 2021 23:58:32 UTC