[Gimp-user] 3 monochromes to 1 RGB

[rich404 <forums gimpusers com>]

> I want to fuse three monochorme images into one RGB image. I was told
> I should use the function color>components>compose...
>
> When I load the images separately, the other images never appear as
> options for the "compose" function. When I load the images as layers
> of a single image, none of them appear as an option.
>
> GIMP help says absolutely nothing about this. It only assumes all of
> them would be available to chose and attribute to a color channel.
>
> What am I doing wrong?

What version of Gimp? 2.8 has a message bottom of the image window tell you only
possible on an image that has been decomposed. https://i.imgur.com/YEiBuSB.jpg
Gimp 2.10 has a big pop-up message.

However, 2.8 or 2.10 you can re-assemble like this:

Open the greyscale images https://i.imgur.com/YEiBuSB.jpg (detached the layers
dialogue for better visibility)

Make a new RGB image like this: black background + 3 layers filled Red Green &
Blue, each with a white layer mask https://i.imgur.com/pTMSJ3Z.jpg

see: https://docs.gimp.org/2.10/en/gimp-layer-mask-add.html

Copy in turn each greyscale image to the appropriate **layer mask**
https://i.imgur.com/YZiVXlT.jpg

Put each layer (R, G & B) into Lighten only mode https://i.imgur.com/MPt6bOV.jpg

rich: www.gimp-forum.net

-- 
rich404 (via www.gimpusers.com/forums)