About the "copy" blending mode

[dk8]

I don’t know what “copy” means in blending mode.
It says in the reference that it copies the previous layer exactly. But when I actually put a paint layer in copy mode, it behaves as if it erases the layer below it. What is going on?

I couldn’t figure it out after reading this topic.

How is the Copy blending mode practically different from Normal?

I notice that Filter layers will use the Copy blending mode by default, but when I switch it to Normal, there doesn’t seem to be a visible change? The most information I could find on Copy is Misc — Krita Manual 5.0.0 documentation , and it says that it’s useful when using Filter layers and masks, but why is that exactly when Normal seems to achieve the same effect? Also, does anyone else notice strange canvas compositing with the following steps? Is this a bug to report? Draw on layer 1 on …

Is this blend mode for use with filter layers and not paint layers? Copy sounds interesting, so I’m wondering if it could be used for something…

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[TheTwo]

@dk8

But when I actually put a paint layer in copy mode, it behaves as if it erases the layer below it. What is going on?

I think this is its algorithm.This is to prevent the overlapping of translucent areas.

@dk8

Is this blend mode for use with filter layers and not paint layers?

Yes, the content of the filter layer needs to completely replace the original content. If you change the blending mode of the filter layer to “normal”, you will clearly see the change of alpha

This is my research, but it is in Chinese:
混合模式-正常与复制的区别 (yuque.com)

[dk8]

Thanks. I was confused because I didn’t understand why an action that hides the layer below is called “copy”.