GNOME Bugzilla – Bug 730488
rotate layer introduces visible corruption
Last modified: 2015-05-23 17:15:29 UTC
Created attachment 276914 [details] The corruption becomes visible in the eyes of the pure Rotating the image introduces dots and strange patterns. When I say corruption I do not mean Soviet Russian corruption. To reproduce (where not forbidden)... 1. make a new image 500px x 500px. I used 8 bit RGB. There are also problems with 32 bit fp linear, but they are less visible. 2. use the bLend tool to make a smooth gradient from black to white; I had black at the top of the image to give that Mordor feeling. 3. Rotate by 15 degrees: Control-shift-R. 4. Expected result: a smooth gradient in an angled canvas. 5. Actual result: an uneven gradient in an angled canvas, complete with strange dots and/or (depending on bit depth) splodges.
Works perfectly fine here.
Created attachment 276967 [details] I can see her eyes With tonight's gegl + gimp it has improved. However, if you zoom in... The enclosed attachment is a screenshot after rotate, zoomed in, showing two corrupt pixels (one of them is green!). Image is 8-bit gamma RGB.
jkh in IRC pointed out that setting GEGL_LINEAR_BUFFERS=yes in the shell fixes the problem, and indeed it does seem to.
Both the bug and the solution still present in the git master. The bug affects scaling and other transformations.
IIRC this bug, as seen by the original reporter, was due to a custom configuration of BABL_TOLERANCE; which was introducing artifacts long suspected of only existing in canada. Closing during spring cleanup of bugzilla.