Need Help with adding color

[rich2005]

I do not know of a tutorial and not really beginner stuff but try;

Use the path tool https://docs.gimp.org/2.10/en/gimp-tool-path.html and
1. Trace around the car body
2. Trace around the black panel

3. Use the body path (path to selection) for layer masks https://docs.gimp.org/2.10/en/gimp-layer-mask-add.html

4. One for the colour layer (in multiply mode) and 5. one for the original image (in normal mode).

6. The other path - black panel - supplies a selection. 7. Use the curves tool to get some sort of match (hopefully) with the main body.

I got this (detached the docks for visibility).



Once that is satisfactory, paint in the colour layer mask to uncover the wheels and the window area.

For you to play with: https://www.dropbox.com/s/r2caeb0xscfyyr...cf.gz?dl=0 1.5MB Gimp .xcf.gz image

If you have a larger image use that. One of those things where larger is easier.