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Why do you get different drawing results?

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Welcome to the forum @Nikolaich


2 hours ago, Nikolaich said:

Why are the results different?

On the left is a black ellipse drawn with an opacity (alpha) of 70 on a layer with opacity of 255.

On the right is a black ellipse drawn with an opacity (alpha) of 255 on a layer with opacity of 70.


I may have misunderstood what you are asking. Could you show us the differences you are seeing please?


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I apologize, I didn't see the possibility to attach a picture. I'll show you an example.

On the left is drawn an ellipse of white color with alpha channel = 70 and the layer is set to transparency 255.

On the right, a white ellipse is drawn with alpha channel = 255 and the layer is set to transparency 70.

See what I'm talking about? It looks like the right ellipse has antialiasing applied, but the left ellipse does not.


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Why did the forum reduce the image for me? Now it can only be viewed normally at 5x magnification. :(

I apologize, I misnamed the tool. I was talking about the ellipse gradient. My mistake.

Edited by Nikolaich
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The gradient tool uses dithering to reduce the amount of color banding. The closer the colors are to each other, the more intense the dithering becomes and alpha counts as well, so alpha 255 to alpha 0 are maximally far from each other, but alpha 70 and 0 are much closer and get dithered harder.


When you change layer opacity, there is no dithering, and you get the banding instead. Here's a synthetic comparison: top part is a gradient from RGBA 255, 255, 255, 31 to 0, 0, 0, 0, on a black background. The bottom part is a RGBA 255, 255, 255, 255 to 0, 0, 0, 0, with layer opacity set to 31. After merging the layers, the visibility was boosted with the levels tool to bring the 31, 31, 31 to 255, 255, 255.



As you can see, the banding is intense on the bottom one, whereas the top one is very fuzzy but you can't really tell the banding. It's a tradeoff and you kind of just have to choose which is preferable for your use.

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