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> Subject: Re: [Gimp-user] What is wrong with this picture?
> From: liam holoweb net > To: strata_ranger hotmail com > CC: gimp-user-list gnome org > Date: Thu, 21 Feb 2013 14:35:07 -0500 > > I don't know where you get your "results should be like this"... you are > not "increasing the magenta channel by 30%", you are mapping all pixels > whose colour value in RGB space is within 30 degrees of magenta to a > completely different hue, to a different location in HSV space.... > > The effect you show happens with all the colour "channels". > > I think you are wanting to increase saturation. > > Or am I missing something? > > Liam > You missed only one (very important) detail: The tool's Overlap setting. IF we left the overlap setting at zero, then we would get exactly what you described -- only those pixels within absolutely 30 degrees of Magenta would be affected, everything else remains the same. BUT with an Overlap setting of 50%, this "blurs" the threshold between Magenta and Red (and likewise between Magenta and Blue). All pixels with hues falling between a 15° ~ 45° deviation from Magenta (a 30° range, or 50% of the 60° between Magenta and its neighbors) will receive a variable percentage (100% ~ 0%, respectively) of the Magenta channel's adjustment. Test it yourself: Paint a simple red-to-yellow gradient, then go to the Hue-Saturation tool and (with overlap = 0) drain all saturation out of Red. Next, slowly increase the Overlap slider and watch how the pixel-sharp threshold between the two channels becomes a smooth fade. It's very useful behavior when you're using this tool on photographs or other images with smooth color transitions around the hue thresholds; it just happens to make one epic screwup in this particular usecase. -- Stratadrake strata_ranger hotmail com -------------------- Numbers may not lie, but neither do they tell the whole truth. |