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PPilmeyer / drawchemy

Abstract drawing application on Android.
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Partial opacity greenifies blended colors #5

Open ShadowKyogre opened 8 years ago

ShadowKyogre commented 8 years ago

I've noticed this for a long, long time and thought it was just my screen. Then I took a color picker to it and noticed drawchemy WAS adding slightly more green even though I don't want it to.

Steps to reproduce:

  1. Set the opacity for the current color (black is best to demonstrate) to half
  2. Start drawing overlapping patches of transparent black

Expected approximate result (made in gimp for comparison):

expected-opacity-blend

Result (made in drawchemy):

greening-opacity-blend

PPilmeyer commented 8 years ago

using RBGA for the manager canvas might solve this issue.

ShadowKyogre commented 4 years ago

So some years later, looked at the api documentation and found this bit about RGB_565 .

https://developer.android.com/reference/android/graphics/Bitmap.Config#RGB_565

Mentions that without dithering, result can show a greenish tint.

DrawManager lines 75 and 79 make a reference to RGB_565.