I got a question if the eraser is really erasing when I try to use the split to alpha feature. Here is my layer:
After I 1. duplicate the layer, 2. use the split to alpha feature, 3. turn off the transparency mask, it will look like this:
I want to know why will this happen, does it mean there is a bug for the eraser tool that is not discovered yet?
It looks like the layer called âFeetâ had a large amount of paint on it that was erased using the Eraser brush or the Pixel brush set to Eraser mode.
The Eraser brush or the Eraser mode works by reducing the alpha channel to zero for total erasing.
However, the hue components (R,G,B) of the erased pixel remains and can be seen, with an alpha value of 1, when the layer is split so that the Hue components and the alpha component are separated.
Here is a similar situation where I âaccidentallyâ put a small amount of grey paint under a painting of a foot and also a large amount of red paint above it. I erased those mistakes:
To fully explain the content of a split alpha layer and its associated transparency mask, you need to know the full history of the original layer in terms of what painting has been done on it and what erasing has been done on it.
Thank you for answering my question.
So, will this consider a bug for the eraser tool that donât remove the hue components and be fixed in the further versions?
Also, is there a way to remove the unwanted pixel instead of using eraser tool?
I made a mistake in using the word âhueâ. I should have said âR,G,B componentsâ.
I donât think itâs a bug. The eraser works because it removes painted pixels from the paint layer.
It removes them by making them âinvisibleâ, i.e. by forcing alpha = 0 for them.
When you use Split to Alpha, you then see those âerased pixelsâ because in the split image content the alpha is increased to 1 and the removal of the pixels is then done by the associated transparency mask.
As you can see from your own screenshots and from mine, if a pixel was never painted then the split image shows it as black. That is because what people think of as an âempty/transparentâ pixel in a paint layer is in fact a black pixel with an alpha value of 0.
What you seem to be expecting is that erasing paint will set the alpha = 0 and also R,G,B = 0,0,0.
Do you have a good reason to require that an erased pixel has the colour black as well as being transparent?
If so, you can create a Feature Request topic in which you ask for that to be done.
Any feature request topic should explain why the current behaviour causes problems and what benefit the requested change will give.
For an explanation of the background and the âtechnicalâ aspects, you can give a link to this topic.
You could paint it black before you erase it.
Also, you could paint it black on the split content paint layer.
Iâve just thought of a workaround to get the result that you seem to want:
Turn off the visibility of all layers except the paint layer that you are interested in.
Then in the Layers Docker, do right-click â New Layer From Visible
That will give a new layer that is the visible content of the canvas at that moment.
If a pixel seems to have no content, even if it has paint that has been erased, the newly created layer will have all transparent pixels as R,G,B = 0,0,0.
Here is a simple example:
The blue and green paint was a mistake that I removed with the eraser.
All paintings are illusions. If you know the tools and you know some tricks, you can change the details of the illusion and nobody (except you) will know that itâs been changed 
Thank you, that is what I want
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