View Full Version : Recombining RGB to make colour image
12th November 2006, 18:10
Hi, is anyone able to tell me how to recombine three B&W images(channels) to form a colour image again.
12th November 2006, 21:55
Let's see...the quickest way I can come up with is this:
1. Pipe every image into its own Color->Mult node; rename every node to MultR, MultG and MultB (the renaming is not necessary for the outcome, but an important habit nonetheless).
2. In the Mult-nodes' parameters, set the values for each corresponding channel to 1 and the rest to 0, i.e. for MultR, leave Color->R to 1 and set G and B to 0. Do the same for MultG and MultB.
3. Now, select MultR and create a Layer->IAdd node. MultR is automatically piped into input A. Pipe MultG into input B. Rename the IAdd node R_G_IAdd.
Watch the output of R_G_IAdd in the Viewer, you'll see a coloured image now, comprised of, well you've guessed it, the Red and Green channels.
4. Select R_G_IAdd and create another Layer->IAdd node. Rename this to RG_B_IAdd and pipe the MultB node into input B.
5. View the output of RG_B_IAdd in the Viewer.
6. Et voila! You have succesfully re-combined the three images into one RGB/coloured image again!
7. (You could, of course, also pipe all three Mult nodes into a MultiLayer node and set the layer blend modes to Add. Should be a quicker way but I completely forgot about this. Hey I'm only human.)
Maybe there are more ways to achieve this (as always) but I think this is the most basic way to give an understanding of what happens in a film image.
You may want to build a macro for this setup, or experiment with colour-correcting the individual R, G and B layers, and thus building your own custom RGB colourcorrector in the process! Or even more fun, working with the colours' complements instead, Cyan, Magenta and Yellow and fiddling around with the values can give some insight into replicating the Technicolor process. Different beast altogether, but what the hell.
Sorry for the lengthy reply but I have no guessing of your experience so excuses if I over-infoed! In that case, hope it helps for anybody else! :twisted:
See ya! :?
13th November 2006, 08:29
That's great, thanks for spending the time to explain it well. :)
13th November 2006, 14:12
A loops picture == thousand words special :)
Nothing like as much control or as much fun to play with as the method above but a damn sight fewer nodes, no? ;)
13th November 2006, 21:29
If you are feeling lazy and that three nodes are too much hassle to add, you could always download the macro I put up on highend2d called, quite catchily, RGBCombine.
This will do the job, AND has a pretty icon.
14th November 2006, 14:52
Cool...the copy node..hadn't thought of that thanx loops great tip :D Come to think of it, I never use it!
Or is that weird? :oops:
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