any way to do hue vs. hue curves in GIMP? hue vs sat/lum/etc?

[clepsydrae]

Hello -- is there any way in GIMP (native or via G'MIC or a plugin) to do a hue vs hue adjustment? I'm aware of the basic color correction tools like Color -> Hue-Saturation that offer coarse adjustment, but I'm hoping for something akin to what you can do in Davinci Resolve, where you can adjust a smooth curve that controls the relationship. This image is showing hue vs luminance, but hue vs hue, hue vs saturation, etc, are all present and useful:



Anything like that for gimp? Thanks!

[rich2005]

Nothing I know like that. Davinci Resolve is a video editor. Can you give an example of a before / after applying a hue vs hue adjustment. I cannot grasp that one.

The Gimp gmic plugin does have colour curves, more variations than Gimp, Lch for example, but they are individual curves to adjust. Also in gmic and maybe applicable to video is applying an CLUT from one image to another image.

[clepsydrae]

lThanks -- Yeah resolve is for video, but darktable has this too, under the name "color zones".

It just takes the X axis as input e.g. hue and the curve determines output e.g. hue on the y axis.

In resolve you can do hue vs [hue/luminance/saturation], as well as [luminance/saturation] vs saturation.

For example, the following attachments, showing the original image, then a hue vs saturation that changes the mushroom's saturation, then a hue vs hue that changes its color, and then a hue vs lightness that changes its lightness. (These are crude examples just to get the idea across.)

It's a great way to selectively alter color in an image in a smooth way. I'm doing some visualizations of house painting and was hoping to be able to selectively and smoothly adjust colors. I don't mind (and will have to do) a little manual masking here and there, but I don't want to have to mask out every leaf and branch in the images to only adjust the colors I need to adjust. GIMP/G'MICs tools (as far as I have found so far?) are pretty coarse, it seems. But I suppose I can use darktable in conjunction. Unless there's an add-on I should know about?

original:
   
saturation dropped:
   
hue altered:
   
lightness increased:
   

[Ofnuts]

What you can do is decompose the image into its HSV components, and use the Hue component (or a transformation thereof as the selection). This technique, when used with Luminosity is called a "Luminosity mask" but it could be used with other criteria for the mask.

[clepsydrae]

Good tip, thanks!