Re: [Gimp-developer] gimp gradients

BTW, this is my personal usecase scenario where editing a gradient in GIMP was unexpectedly a painful thing:

I was trying to create a sepia-like gradient -- a gradient that fades from black to sepia (for simplicity, let's just say RGB #804000) to white.  Y'know, something I can just Gradient Map onto a grayscale image later on.

This poses several challenges:

1 - Because the endpoints are black and white, any blend between those endpoints will only ever produce a greyscale gradient.  This applies in both RGB and HSV space (black and white by definition have saturation=0).  Therefore I require a node in the middle to specify the desired color.

2 - Because I will be tweaking or changing the color to suit my tastes (there's a specific image I'm trying to match), and this gradient is contiguous, I constantly have to tell GIMP to "Load endpoint's color from > neighboring endpoint" every time I make the slightest tweak to the node's color.  This doubles the number of steps I have to perform just to set one color -- but as a small optimization, I can simply tell GIMP to use my foreground color in the meantime.  The only problem with doing that, though, is once I'm finished tweaking the color I have to set the color type (and remember, on both sides) back to "fixed" before I save the gradient and quit GIMP.

3 - My chosen RGB tone doesn't exactly carry the same luminance as a 50% grey, does it?  So I need to apply the equivalent of a midtones/gamma adjustment to it.  I set each segment to Curved blending, drag this node to the left, brightening the overall appearance of the gradient....

4 - But I see another problem - the midpoints between nodes (white handles) don't move in  proportion to the overall length of their segment.  So I have to adjust them too.  Now instead of just manually positioning one handle, I now have to manually position three.

5 - And because this gradient should approximate a curved blend, I can't just re-center the handles in their respective segment - if my middle node is 40% from the left, each segment's midpoint also has to be 40% from their left endpoint too.

6 - And did I mention that I'm alternating between tweaking both the color and position as I go along?

7 - Cue banging of head against the keyboard in frustration and having to undo whatever steps GIMP may have interpreted those keystrokes as.  (Oh, wait, the Gradient Editor doesn't even have its own undo system -- cue banging of head against monitor....)

Now in some alternate universe where editing gradients is done solely on a conceptual level, I could have just:

a - Specified the starting color (RGB black) in HSL values of:  hue = 30°, saturation = 100%, luminosity = 0%.
b - Specified the ending color (RGB white) in HSL values of:  hue = 30°, saturation = 100%, luminosity = 100%.
c - Assigned HSL color mode to the segment.  (midpoint of segment becomes:  hue 30°, saturation = 100%, luminosity = 50%, a.k.a. RGB #804000)
d - Specified Curved blending on the segment and adjust the midpoint until I get the desired result.
e - Done!

Yeah, that would be nice....

-- Stratadrake
strata_ranger hotmail com
Numbers may not lie, but neither do they tell the whole truth.

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