jjhunter: Watercolor of daisy with blue dots zooming around it like Bohr model electrons (i make icons now)
jjhunter ([personal profile] jjhunter) wrote in [community profile] gimp_gate2011-10-05 01:32 pm

What are some tips & tricks for matching color values of different lighting types?

I've seen some gorgeous photo manips where the artist adjusts for the effects of different types of lighting in different pieces of the source material. What are some good ways to do that? In the collage I created under the cut, I used 'Adjust Hue / Lightness / Saturation' under 'Colors' to, e.g., lower the saturation of both cyan and 'master' in the 'TARDIS console' layer. I was essentially matching it on the fly by eye, but I'm curious whether there's some use of, say, the eyedropper tool en masse to get a sense of the general color balance patterns

Other techniques I used include reduced opacity erasing to an alpha channel (dollhouse and sleeping man layers); duplication, rotation, and movement of the Sagrada Familia layer (Gaudí cathedral); and merge down (Escher layer to dollhouse layer).



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melannen: Commander Valentine of Alpha Squad Seven, a red-haired female Nick Fury in space, smoking contemplatively (Default)

[personal profile] melannen 2011-10-05 08:33 pm (UTC)(link)
My absolute favorite tool for that kind of adjustment, when I'm working with photos, is "curves" under the colors menu. You basically just play with the line it gives to to adjust the value of any pixel - it's like working with saturation/contrast/value/lightness all at once, and you can do things with it that would be really complicated to do with the sliders. Also,the gray behind the line is a graph of how many pixels of each value you have.

I haven't worked with it in colors much, but you can set it to only do one color at a time, adjusting the values of red/green/blue separately, and with the same graph showing for the color values of each pixel.

Levels is similar to curves in some ways, but it comes with an eyedropper - you get to pick an area of the image that you want to become white/black/midtone for each color, and it adjusts the whole image relative to that.