Hello All...
Basic Q, I think, but having trouble finding an answer I need to move or copy the Red Channel to Alpha, and Green to the Red & Blue channels...How do I do it please? I don't think it's possible to copy and paste channels. I've tried 'Drag & drop' too, but no success.

Reason I want to do this is to remove the 'blue' from a Normal Map...I read somewhere it can be done...Can't remember where though probably 'barking up the wrong tree' with this one
Can anyone help please?
Thnks
Ralphc

Have you tried Colors>Components>Channel Mixer?

Not sure if this is what you are after but just had a play around and found this, so don't ask me to many questions on it as I probably won't know.

1. Open image in gimp. If the image has no alpha channel, right click on the layer and from the drop down menu select "add alpha channel".
2. Go Colours>Components>Decompose and change the colour mode to RGBA, click ok.
3. This will open up a new image with four layers named red, green, blue and alpha. Select this image.
4. Go Colours>Components>Compose and change colour mode to RGBA, here you can change which layer is controlling what channel then just click OK.

Hope this helps.

The RGB channels at the top of the Channels list don't really exist anywhere... they are the result of the composition of the visible layers. You can just copy them elsewhere if needed (drag to the bottom of the list to create a copy).

You can decompose the image in three R, G, B layers using Colors/Components/Decompose (and recompose the image later after editing each layer).

You can also work directly on your original image: right-click on one of the RBG Layers; and use the channel to replace/add/substract/intersect with the selection :.

For instance to move the red channel to alpha:

• Red channel -> Channel to selection
• In Layers: add layer mask -> init from selection -> apply mask

To exchange channels:

• Create one black layer for each output channel
• For each input channel
  
  • Channel to selection
  • Select target layer
  • Bucket fill selection with target color for layer
• Add the layers

Hi
Thanks all for your time and effort replying ...Certainly lots to look at and try out. I'll learn a great deal I suspect applying your suggestions. I'll feed back the results..well, I'll try to
Best Wishes
Ralphc

Hi Again..
Well, tried them all with varying results probably to do with my inability to follow instructions All 'work,' with slightly different results

I've attached an image of K1TesseraE suggested method, it seemed to work and represents the results. Thing is, I've now got a curious green line on parts of the image. I messed with the 'opacity' and it seems to remove it. I also duplicated the layer using 'Grain Extract' layer mode. So, all in all, helpful with some 'tweaking'

It's worth adding, whilst I was doing this, I learnt a lot about GIMP using tools I never would have used...so thanks for your help..good site this for tips
Ralphc

Hi K....
Thanks again for replying and apologies if I'm not making myself clear I remember your kind offer to help and I've kept it in mind...

"I still can't figure out what you're trying to achieve." ...No wonder as I'm not being clear...

Basically, I'm trying to repaint an aircraft for the Flight Simulator 2009 (FS9) I've attached an image of one I did (repainted) earlier that I've put on a couple of FS related sites

Basically, I've got the template, ( first example attached) which I repaint. I then save it in GIMP as a .png...move it to another programme, which changes it to a .bmp format. Then, I load it into the programme (FS9) as, for example bm_fuse_1_t.bmp It then appears repainted as a new aircraft, which is 'flyable.' (hopefully)

What I'm trying to achieve is to bring about a more realistic base texture, highlighting panel lines, rivets, window frames etc. I've used the Bump Map...and that seems to work OK, the Normal Map could give a better effect I think. Your Q re: 2D or 3D? I'm assuming it's 3D....but, with my limited knowledge of these things, I wouldn't bet on that being right

Hopefully, I've explained why I'm trying to do...apologies if this a little 'long winded' but, I'm on a steep learning curve with GIMP..even with the basic technical stuff.....which I keep stumbling across.
Thanks
Ralphc

Morning K...
Thanks for replying. Phew!! Glad it's clearer now

"The only thing I don't get is why you don't save your maps as .bmp in GIMP."

To answer that Q, I think (and no open another can of worms) I just do...Basically, once I've edited in GIMP..I save it in a file (as .png) then open it in another programme called DXTBmp..you can do some editing in that (I don't) and then send (as a .bmp file) it to the FS9 programme with the correct file name so that FS9 can 'read' it. Somewhere along the line, I saved it in GIMP as a .bmp and lost the Alpha effect (I seem to recall)

.bmp is the favoured format for FS9 - FSX (the later version) can use both .bmp & .dds files. GIMP can use both I know.

I just tend to do 'export to' as well. GIMP (2.8) seems to only save in .xcf. (probably wrong there) When I've finished and sometimes as I work, I 'save a copy' in .xcf and reload later. (GIMP has crashed a couple of times on me)

So, I think we're on the right track I've been doing some more research (the more I look the more complicated it gets)

Your help is valued. Hope this isn't taking up a lot of your time
Thanks
Ralphc

Hello K...
Glad that you found the time well spent. Me too So, As it stands, I'm on the right track. I recall that you said that the green/pinkish lines that appeared after I'd used your method of removing the blue 'sheen' were part of the process. I suspect, when I paint over these, they'll be hidden (hopefully)

I'm going to go back to the vid in the link you sent me right at the start and watch it again. I think it will make more sense.

I do have Blender too, but TBH...I'm sort of staring at it in a world of confusion More tuts needed I think!

I'll send in an image of my finished (eventually) project. I'll just have to stop experimenting!!

Thanks
Ralphc