GIMP Version: 2.8.14
Operating System: Windows
GIMP Experience: New User

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Hi, I have the feeling this may be more of a tech forum than a how-to, if I'm right please suggest other places I could get advice....but......

I am pretty slow and dim when it comes to layers and masks. I have only just figured out, courtesy of the GIMP manual, how to de-saturate a pic and then re-introduce colour by duplicate layer, add mask and then painting over. But for subjects with fur (almost all of mine) the painting-over is never going to be accurate enough. Browsing Youtube, I found out about Threshold, and can use that to isolate my subject (a horse) nicely enough. But for the life of me I can't work out how to lay that "silhouette" that over the image (right term?) to use as a mask and then only apply (in this case) the re-colouring to the masked area...

Could someone be very very very kind and try to explain how to do that in a series of one line idiot proof steps?

Thanks in advance.

If you duplicate your horse layer and create a silhouette of the duplicate, it is in correct position automatically.
I think your problem is that you did not invert the colors?

Step 1.
Duplicate layer. desaturate (or extract blue channel), brightness-contrast, some black brushing on the horse.
Invert colors.



Step 2.
On the BW layer, select all (Ctrl+A), Copy (Ctrl+C).
Right-click the original layer to bring up contect menu, "add layer mask" (White full opacity)
Ctrl+V, anchor layer.



Now you could color over the horse, just remember to switch from layer mask to the actual image!



If you want to keep the horse as reference to paint accurately, create new transparent layer and use same layer mask.
Draw on the the transparent layer. (Changed blending mode to LCh color, it's not available on 2.8, but you can use some other blending mode, all depending what kind of overcoloring you are looking for)

dweeble: Welcome to GC! The forum moves quite a lot depending on what members are more active at the time, so please don't be discouraged or scared off if we're having a techie day . First time I ever heard of layer masks I thought it sounded scary and complicated, but when I got round to using them I felt like a wzard. Nidhogg gave you good instructions here, don't be afraid to come in and ask if you need clarification or an alternative method (there are always alternatve methods and usually plenty of them) or something. Good luck!