P: Knockout behavior changed

[Nahum Reduta]

Before PS 2020, layers with shallow Knockout enabled and reduced Flow could be clipped to layer groups. These clipped layers would interact with each other, mainly allowing separate shadows to be added without stacking with each other.

When opening the same documents in PS 2020, the clipped layers with knockout give wildly different results. Solid color fill layers blend in Normal mode despite layer blend settings, and cause the attached group to also reduce in Flow, making these areas partially transparent. Regular layers appear to have a per-channel effect, with Flow and Opacity serving completely different purposes from before.

When playing with the "Transparency Shapes Layer" setting in Blending Options, it appears that PS 2020 show the previous behavior in preview, but continues to do the unwanted behavior when committing a change. (The setting doesn't actually change the result.)

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Top left: PS 2019 and Shade 1 shape
Top right: PS 2020 and Shade 2 shape
Bottom left: unblended contents of Layer 1
Bottom right: Layer 1 blending and clip

If the upper Shade had Knockout enabled, it would also show gray in PS 2020, while causing no visible change in PS 2019.

[Yves-CH]

look here the video https://feedback.photoshop.com/photoshop_family/topics/bug-report-photoshop-2020-version-21-0-0-crop...

[J453]

Nayhem, can you post your PSD for troubleshooting? (link to dropbox or CC Files)

I believe it is related to this: https://feedback.photoshop.com/photoshop_family/topics/photoshop-cc-2020-layer-effects-on-groups-cli... but want to confirm. Also try the workaround in the aforementioned link to turn on Legacy Compositing to see if the problem goes away.

[Nahum Reduta]

Sorry for late reply. Try this link: https://adobe.ly/2XbhooL

Enabling Legacy Compositing in 2020 does have the desired effect. Meanwhile, disabling LC in 2019 does not cause the problem to appear. Restarting PS or WIndows causes no change.

I vaguely recall seeing something like the other problems in 2019 on occasion, and it seems to continue in 2020. For me, it seems to be related to blending gamma and cache levels during zoom, along with a larger number of feathered/transparent layers.

[Nahum Reduta]

This whole process seems to work better when email notifications aren't piped to spam. 😛

[J453]

Thanks. This is perfect. Will look into it.

[Wabber_HM]

I'd like to add on to this issue with a similar issue I've encountered that might have to do with the same thing. I was using a vector shape to cut out the document in the shape of that shape in real time. Here is a link to a file that does this: http://ge.tt/3R424E73

To do this, at least 1 group with 2 layers and one layer outside the group is needed. The first item in the group is the shape layer and I have its Fill Opacity at 50% to demonstrate this bug. The Knockout for this shape is also set to Shallow. Below that, I have a Color Fill layer that is set to Knockout Deep. Fill Opacity won't matter for this demonstration, but it can be set to 0 to have only the shape show through.

Finally, when editing the Blending Options of the Group these are contained in, toggling the Blend Interior Effects checkbox or adjusting the opacity or Fill with the Preview checked on will show an incorrect preview of the shape knocking out through to the transparency, skipping the layer outside the group. Clicking OK will revert to the previous state where it did not show transparency. Enabling Legacy Compositing will prevent this preview issue from happening.

But what's not adding up is how Knockout behavior was changed. In my example, it's just temporarily previewing incorrectly, but the output is the same regardless of the compositing engine used, because the result is expected.

[J453]

Fixed in 21.0.2 or later