[compositing] comp-op="dst-out" issue #1797

Andrey-VI opened this Issue Apr 3, 2013 · 2 comments


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I found strange behavior (I think it's a bug) using a lot of layers with comp-op="dst-out" and opacity="0.5" settings. I made a small test-case for this issue:
There are 2 images. The first image made with only layers "0" and "RGB" enabled:
With this image the only one thing is strange: opacity of the low grey part not 0.5, but 0.49 (or 127 instead of 128). So (128,128,128,128) became (128,128,128,127).

The second image made with the layer "0" is turned off:
A lot of issues here.
a) The RGB-squares now with alpha transparency 195 of 255 (0.76).
b) The first line of 6 gray squares with invalid color and opacity:

  1. (32,32,32,62)
  2. (32,32,32,63)
  3. (31,31,31,64)
  4. (31,31,31,65)
  5. (30,30,30,66)
  6. (30,30,30,67)
    с) The second line of next 6 gray squares also with invalid color and opacity:
  7. (123,123,123,122)
  8. (124,124,124,123)
  9. (125,125,125,124)
  10. (126,126,126,125)
  11. (127,127,127,126)
  12. (128,128,128,127)

But the second image should be the same as the first!
Hope this helps.

cc @artemp
(Artem, did you received my letter about this issue?)

Any help on this bug?
This is blocking issue for our new hybrid maps design.

cc @artemp


artemp commented Apr 10, 2013

@Andrey-VI - thanks for reporting, I'll look into this issus asap.

@springmeyer springmeyer added post3x and removed post3x labels Sep 6, 2014

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