The following version of the script works with layermasks or channels. To create a channel from one of the red, blue, or green components just dragon-drop the thumbnail preview from the top (components) section of the Channels dialog to the bottom (channels) section. Make sure that the component is still active after the dragon-drop (see bug #696008).

http://chiselapp.com/user/saulgoode/rep ... 99c37cda66

I'll 'fangirl' a little more here, this is still awesome. thanks Pat.

I don't get it. I downloaded the saul goode version, and really can't get it to do anything interesting. Is this for use only on desaturated Base images? To use as a mask do you edit in channels? Is there a tutorial on how to use the script to best advantsge??? Once again hopelessly lost in the complexities of gimp. I HAVE read the tutorials, and they don't make much sense to me. I am not a beginner in gimp, been using it 4-5 years.

To use one of the channels as a layermask, you would perform "Layer->Mask->Add Layer Mask..." on your layer and when the dialog appears to present the options for the initial contents of the layermask, choose the "Mask" radio button and select the appropriate channel from the dropdown box.

If it helps, here is the relevant section from the blog post about using the masks.

Thanx for the answers, just returned accidentally, had forgot about this site. Been working real hard for the last 6 weeks trying to REALLY learn and it is finally starting to come together. Pat, I revisited one of your tutorials on masking that I couldn't make sense of and all of a sudden a light turned on and I was able to construct a mask for a specific reason different than your tutorial, and salvaged a really nice photo. Thanx to all of you for putting up with cranky slow learners. It gets so frustrating until the light clicks, then it's pure enjoyment.

Nice to see you are doing well in Gimp kjacobs4242. There is so much to learn but you did come to the right place for help to any question you have concerning Gimp. Just ask away and someone will come to your rescue, we have a great group of members that are very talented and are anxious to help.

Part of the problem I see with many tutorials is they don't make it clear what the end usefulness of a technique is. I went thru one that showed blending of Layer modes, using 2 different pictures to show how they blended. I couldn't figure out why any one would want to blend baby ducks and a metal cylinder. It took some time to realize for me the usefulness was in blending versions of the same pic to get better contrast, or colors. Once I saw that it all made sense. For many I suspect this is the case, once you understand the real world use it makes sense.

Thanx Molly. I had thought I was a member here, but it was at Gimp Forums, and I see some of the same people here. Was actually trying to post there and got back here by mistake, LOL. Ofnuts has been a big help to me for a couple years at the forums.

Indeed, this is one of the things I always try to keep in mind when I start writing something. I've always learned much better when I can find an applicability for the techniques I may be exploring. I'm glad you've managed to get a handle on some ideas! It's all downhill from here! Soon you'll be masking and blending like a pro, I'm sure.

As always, feel free to poke me as needed. Spend enough time here on the forums and you'll learn a lifetimes worth of interesting things...

This is coming from someone who don't understand all of these jargon. But, what does the Luminosity mask do? In a way that I would understand.

The masks will allow you to modify parts of an image based on their luminosity (brightness-ish). If you wanted to color only the shadows of an image, you could add a solid color layer and mask it with the dark luminosity mask to confine the coloring to just those dark tones (usually leaving the light and [mostly] mid-tones alone).

Mostly just a way to target modifications of an image to particular regions (based on perceived brightness).

Does that help?

Just a quick and HUGE thanks to Pat David for such a great set of tutorials and for being so available for newbies and lost souls!

You're very welcome, but I am only a single tooth in the gears. Don't forget all the others that do a far better job than I of helping folks!

Hi there, I am learning so much from you regarding
GIMP and the various things you can do. I have read and studied your tutorial on Luminosity Masks and have a question. I have tried to download and activate the code you and even Saul developed. I can download both of them, but how to I get it into GIMP? Hoping you can help... thanks so much..

I recommend using the Ofnuts luminosity mask. See here:
https://www.gimp-forum.net/Thread-ofn-luminosity-masks

Important Note
If you define your own masks be sure to read the docs on how to update!