I am using the latest GIT of the STABLE branch (2.6.8) and am noticing
an anomaly when scaling layers. When upscaling a fully opaque layer
using the Scale Tool, the edges of the resulting layer are sometimes
have partial transparency. This doesn't always happen -- it seems
dependent upon the original and target sizes -- but it never seems to
occur when using "Scale Layer..." from the menus. While I am not sure
it should be considered a bug, my expectation would be that a fully
opaque layer should remain fully opaque when upscaled.
To demonstrate this behavior, create a new white image with the
dimensions 335x500, then create a new black layer with the dimensions
120x135 positioned with the top-left corner at 0,0. Using the Scale
Tool, type in the new dimensions of 335x500 and click "Scale". If you
zoom in on the lower-right corner, the semi-transparency of the right
and bottom edges should be evident.
Repeating the above, but using the menu command "Layer->Layer
Scale...", you should see that all of the edges are completely opaque.
I would also note that the behavior described in Bug #603620
(https://bugzilla.gnome.org/show_bug.cgi?id=603620) may have similar
underpinnings, and that the author of that report suggested this was a
regression from GIMP 2.4 behavior (I don't have access to 2.4 at the
As a final comment, the PDB functions 'gimp-drawable-transform-scale'
and 'gimp-drawable-transform-scale-default' both exhibit this
anomalous behavior (for all interpolation modes except None). Indeed,
it is when scripting that I find this behavior problematic.
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