After doing some testing with my companies c300 last week, we determined that the cinema lock (c-log) mode, and the cinema picture profiles have completely inaccurate colors!
Greens were skewed into blue, and reds were skewed into orange.
Very simple, just a quality grey card, macbeth color checkers, human face, and some problem fabrics in the shot.
Shot both daylight and tungsten. Metered shot, grey balanced off the card, and then checked for balance with the RGB waveform.
Some of the picture profiles we tested had correct colors. The EOS standard was the most accurate.
C-Log was radically skewed. Grey was correct, and the face was correct. But the green turned blue, and deep scarlet red turned orange.
We tested another camera against ours today. Exact same rendering of the green color! (As cyan).
If for some reason this is standard for the camera, C-Log is now unfortunately useless for any work involving accurate color reproduction.
Hmmm. Time to talk to the Canon Head Office.
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07-14-2012 06:45 AM
Last edited by Matthew Bennett; 07-19-2012 at 04:05 PM. Reason: Updated July19/2012
07-14-2012 07:49 AM
Sounds strange - my experience in testing has been the complete opposite. C-log has been the most accurate for me, while EOS has a pleasing but exaggerated color profile.
Is this what your camera looks like?
07-16-2012 04:02 PM
my guess is that you are color correcting the Canon Log improperly. Can you post the curve you've been using to color correct the footage? I find in Apple Color and DaVinci that you mostly adjust the bottom 1/3 of the curve the most directly.
Your stills look to me like you've pull the mids too far up.
07-16-2012 06:27 PM
You can't trust color accuracy in FCP.
Also, have you bypassed what Apple is doing to your colors by using a Black Magic Intensity Pro card?Bill Totolo
07-16-2012 08:40 PM
We worked the same footage in Apple Color and After Effects, with similar results - the green color of the shirt is being completely mis-represented in C-Log as well as many other picture profiles we tested.
I'm not a camera engineer, but this behaviour from a camera is bizarre, and well - unacceptable as our work is based around strict color accuracy. (as I'm sure pretty much everybody on the planet's is.. ;))
Anyway, we're taking it back and getting it replaced...
07-16-2012 08:44 PM
Haven't tried a BMD card even though we have one at the office...
The clincher is that some of the picture profiles reproduce the color well (varying degrees), with EOS STD being almost perfectly accurate.
We're going to test another c300 unit against ours, same setup, and see if the results are the same.
07-17-2012 08:46 AM
Matthew, my experiences are similar to your findings. Green is skewed to cyan in Cine gammas with low saturation. When shooting green screen with Cine gammas, the green looks blue. It is possible to go into the matrix and adjust for REC709 with a Chroma Du Monde chart.
There is also the zone based color correction circuit, but I haven't figured that out yet.
For what it's worth, I've had similar experiences with Panasonic cameras being green deficient out of the box, but in the case of the 2/3" high-end cameras, very easy to get accurate color points with matrix and color correction menus. I've had the same issue with EX1's, but harder to correct.
Here are my matrix color points for a more accurate REC 709 C300 file, this is just a rough baseline, but should get you closer:
Hope this helps, YMMV.Jeff Regan
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