The colorpicker currently has a sample radius limit of 9 pixels. I'd propose raising this limit -- if the user is trying to sample e.g. the skin color from a very high-res photograph (or worse, a photograph that has been up-scaled), sampling a 9px radius circle is still not quite enough to get a good average of the color, due to the camera noise et cetera.
Ideally I think the tool could be able to show a brush outline which indicates the sample radius, although just upping the limit would fix the issue too.
The current workaround I'm using is to just downscale the image 4x or 8x, and then sample.
I agree -- what would be a good maximum? The maximum is defined in the wdgcolorpicker.ui, changing that fixes the tool. I also agree with the cursor suggestion.
Git commit aa8a176e1a9e2e114b3375e1028b86c8f52e78d3 by Boudewijn Rempt.
Committed on 28/01/2015 at 15:18.
Pushed by rempt into branch 'calligra/2.9'.
Related: bug 900
M +21 -34 krita/plugins/tools/defaulttools/kis_tool_colorpicker.cc
M +4 -1 krita/plugins/tools/defaulttools/wdgcolorpicker.ui