(08-10-2025, 05:34 PM)Ofnuts Wrote: You don't need a "mask" (or at least not the "mask" concept as understood in Gimp). .There are plenty of tools to shift colors slightly.

* Colors > Color temperature an increase the intended temperature slightly (this is a prime candidate if you have two image that are likely two photos of the same source, but taken with a slightly different white balance)
* Colors > Hue chroma and slightly reduce the hue
* Colors > Hue saturation

The ultimate tool for this is a CLUT, using the GMIC plugin. Using the before and after images it will produce a Color Look-Up Table (CLUT) that maps the colors between the two images. With the same plugin you can re-apply the CLUT to a different image to obtain the same result (in theory, in practice you can only apply it to a similar image, a CLUT created using an image with plenty of reds  may not give good results on an image with plenty of blues.

(08-13-2025, 11:55 PM)AceMcHammer Wrote: ried the CLUT filter (Colors/CLUT before - after layers) and so it says that I need to layers to run the filter.  So I just simply duplicated the layer which gave me two layers but the filter still wouldn't run.  All I'm trying to do is make a color look up table of my preferred image and apply it to my uncropped high res image  

(08-14-2025, 12:04 PM)denzjos Wrote: That should be the clut:

Unzip the file (and remember where you unzipped the file).  
Then use G'Mic-Qt

(08-14-2025, 07:13 AM)Ofnuts Wrote: Yes, GMIC is a bit fiddly. You can tell it to use All layers, but first and foremost, you need to have two identical image that only differ by the colors. And the images you show haven't even got the sale size. So your first task is to use the Unified Transform tool to make them overlap, and then crop the image to some common part. Then you can use GMIC, asking it to create a new layer, and it will create this:



As a test, reapply the CLUT to the first image, and you get this:

(08-14-2025, 07:25 AM)rich2005 Wrote:

(08-13-2025, 11:55 PM)AceMcHammer Wrote: ried the CLUT filter (Colors/CLUT before - after layers) and so it says that I need to layers to run the filter.  So I just simply duplicated the layer which gave me two layers but the filter still wouldn't run.  All I'm trying to do is make a color look up table of my preferred image and apply it to my uncropped high res image  

A bit more about the gmic cubic look-up table (CLUT)  filter



As it states you need two images one before and one after. Unfortunately your small before / after images you posted are not geometrically identical, so you will have to do a bit of image matching.  Once you have done that and using gmic

(1) The two layers
(2) CLUT from before after
(3) Set the output mode
(4) Give the generated CLUT a name
(5) Set input layers to All

Ok that and it makes the CLUT

Now in your large image and gmic
(6) Apply External CLUT
(7) Find the CLUT just created
(8) Always a good idea to output a new file, just in case you screwed up.

(08-15-2025, 06:44 AM)denzjos Wrote: Over the years the same difficult problem has come up here on this forum. Here are some of the possible solutions:

1 - Try this with the two photos : https://github.com/samrocketman/home/blo..._match.scm (script)
Channels to use : 'LAB - Preserve Luma' or 'YCbCr - Preserve luma'

2 - https://patdavid.net/2012/07/getting-around-in-gimp-more-color

3 - You can try this : GMIC-Qt / Colors / Transfer Colors (PCA)

4 - https://www.dustfreesolutions.com/CT/CT.html

(08-16-2025, 09:44 AM)rich2005 Wrote: This is a bit off-topic, it is more general that applying a mask.

For those of you with a gmic plugin, in the Color Presets section there are hundreds of pre-made look up tables (LUT). You can select a pack and scroll through the presets. Also the first entry is to render a collage for a comparison of the effects. Something for eveyone.