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Isolating pure primary colors without white?
I have been given a 3D-rendered sequence containing only elements of:
Pure Red 255,0,0
Pure Green 0,255,0
Pure Blue 0,0,255
Pure White 255,255,255I am trying to isolate these four different values to use as four separate mattes.
Normally I would work with separate B/W mattes for each element I needed to matte, but I have been given this sequence from an outside source.
The trouble is that white contains all the colors, so whether I choose R, G, or B, white is included. Ironically, keying does not give pristine results
Is there a channel effect I can apply which will isolate only pure colors of either R,G, B, or white?
Thanks!
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12 Replies
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– Have you tried a Luma Key instead of a chroma Key? Luma keys are designed to pull out blacks and whites.
– Also Perhaps you can use the “Change to color” effect to change it to a color you can key out with keylight.
Just suggestions – no idea if they’ll work…
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Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
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Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com -
If it’s what I think it is, have them re-render it properly with the 3 primaries plus black. I take it it’s a 3D pass to get 3 channels of data in one render. Like a normal map, or a lighting map.
Chris Smith
https://www.sugarfilmproduction.com -
Thanks for the suggestions… tried the luma key but it’s very crude… looking for a better degree of precision than that.
Surprised AE can’t make the differentiation, though I appreciate that White = 100%R+G+B (!)
Think it’ll just be easier to request the channels as seperate sequences. Live & learn…
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Just a thought: if you take out the R, then the G, then the B, what’s left?
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Chris, you’re completely correct.
I guess they were trying for four different sets of data in one pass….
Pleased to know it couldn’t be done with white & that I wasn’t missing some channel functionCheers –
M -
I totally missed the 3D nature of your render. Well, good to know chris was on top of it.
Good luck.
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Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
—————————————-
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com -
You could use the alpha channel as the 4th channel. If you can get your 3d program to write data to that channel that is not transparency. Then when you import it to AE make sure the alpha channel option is set to ‘none’.
However it seems like a real bear to do. I would just deal with the 3 channels at a time.
Or you can look at Open EXR which has generally unlimited channels. AE 7 now uses Open EXR, but I’m very unfamiliar with how to implement all the channels in AE. In Nuke for example it sees Open EXR very similar to a multi track audio tape. It allows you to split the tracks and do with them what you please. This way you can keep many, many passes from 3D all self contained in one file.
Chris Smith
https://www.sugarfilmproduction.com -
In response to Steve’s post –
If I take out R, G & B I’m left with black.
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If it really contained only “pure” colours, then I don’t understand why it couldn’t be keyed cleanly. Did the composition match the dimensions of the file? Are there mixed colours, like red and blue overlap to make purple?
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He may have meant use RGB to mask out everything that isn’t white.
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