RGB tinting and compositing in Premiere Pro 1.5
Posted 05 October 2006 - 10:19 PM
I'm trying to play around with color, by filming in black and white. I've got test clip of a still scene that I shot three times, once with each of the three primaries as a filter. So, I've got the color records in BW form. I've tried numerous ways to convert this to rgb, but with middling success. I've tried tinting, color balance, nothing seems to yield very pleasing results. Also, I'm having trouble trying to composite the image. I've tried working with opacity, but again, mixed results. Perhaps there is a keying effect?
Posted 06 October 2006 - 07:24 AM
Layer your three files up in the timeline. From top to bottom, R>G>B
Apply an "Arithmetic" filter to the red filter, set the Operator to Max and set the Red Value to 255.
Instead of a Black and White image, you should have a Black and Red image.
Do the same for the Green and Blue layers, set the operator to max (on both) and set their respective colour values to 255 (green layer, r = 0, g = 255, b =0 and blue layer, r = 0, g = 0, b = 255)
Now apply a screen key (Premiere doesn't seem to have transfer modes) to the red and the green layers.
That should be it. Hope it helps.
Posted 06 October 2006 - 02:35 PM
This is much more (needlessly) difficult in Pro than it was in 6.5; the compositing arrangements in the recent versions of Premiere are a pain.
You will have to precomp two channels then put the third over the result. In the first timeline, dump your red record above your green record and apply the levels filter to both, using the solid black handles to remove everything except the appropriate channel from the greyscale images. Then put the overlay filter on the top one, set to Screen. At this point you'll have a red/green/yellowish image.
Then, create a new timeline, and put the first one on the bottom track; dump the blue record above it. Repeat the levels trick with the blue record and Screen it over the first precomp. You should, subject to the mathematics of the Screen operator and how well the primary filters you used match the chips in the camera, have something approaching a colour image.
Posted 07 October 2006 - 03:58 AM
Nope, what I outlined was for doing it in Premiere Pro 1.5. Reading what I reply with originally, I didn't make that clear at all. Sorry.
Are you talking about doing this in final cut?
If you can read Shake nodes, here's how the idea works.
All we're doing is taking the colour value from each pixel and adding it to the final image (A screen key will do the same thing in Premiere).
So in the above example the values at 1594, 534 (part of the surrounding green screen) read something like this...
R Layer: R = 0.345 G = 0 B = 0
G Layer: R = 0 G = 0.7333 B = 0
B Layer: R = 0 G = 0 B = 0.235
So if we add up all the red values we're only going to get a final value of 0.345 and if we add up the green values we're going to get 0.7333 (you can see where this is going right). In the end we're going to get something with a lot of green and a little bit of red and blue mixed in as well.
I used an AdjustHSV node in Shake just cause it was there, you could probably use a similar Colour Adjustment fitler in Premiere to tint the individual colour layers, I believe there is a Tint filter effect in Premiere you could use. Levels will work as well - like Phil suggested. You can also add other filters to each layer to see what effect it has on the final RGB image.
You shouldn't need to precomp anything in Premiere - you can, but it seems unnecessary - we're only dealing with three layers.