Film-Tech Forum ARCHIVE: Barco Color Calibration

This is topic Barco Color Calibration in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Phil Ranucci (Member # 3820) on 04-27-2015, 12:51 PM:

Question about calibrating color on Barcos.
After measuring native colors and applying the correction, we selected color verification as the target color source and verified the corrected colors and white was spot on. But a white test pattern called up on the Barco (corrected or uncorrected} was way off. If we ran the GDC framing chart the white was correct.
What am i missing? I thought test patterns were stored on the ICP board which also does the processing, so why isn't white white?
Thanks!

Posted by Steve Guttag (Member # 268) on 04-27-2015, 01:00 PM:

If you are calling the white (or any other pattern) via the Test pattern section of communicator, it is likely that the TCGD is no longer Color Verification and that you are now reading via the TCGD buried in the PCF for the format that is selected.

Note, officially, color is supposed to be read by playing an appropriate pattern from the SERVER not the projector. That would ensure that the entire signal path is accounted for. Does anyone do that outside of 3D? Probably not too many though it is easy enough to do the verification that way.

Posted by Dave Macaulay (Member # 813) on 04-27-2015, 02:49 PM:

You can get a white pattern dcp from freedcp.net. When projected it should read 0.314/0.351 after calibration. Just play it and pause, it will project white until ejected. This is good for 3D as it will run your 3D adapter at sync speed.

Posted by Steve Guttag (Member # 268) on 04-27-2015, 03:16 PM:

Note, anyone that has access to Dolby's customer site can download their 3D test patterns so you can get all four stimuli. They will work for 2D or 3D color tests.

Posted by Marco Giustini (Member # 4544) on 04-27-2015, 03:34 PM:

I use the internal patterns but always verify via server. As Steve says that accounts for everything. Also I found that white from server is usually slightly less bright than white from projector.

Posted by Dave Macaulay (Member # 813) on 04-27-2015, 03:57 PM:

White patterns are basically uncorrected color. You can't add more green to the colors so to get that you turn down red and blue... corrected color will always be a bit less bright than uncorrected - unless by some miracle the uncorrected color reads 0.314/0.351.

Posted by Justin Hamaker (Member # 2165) on 04-27-2015, 03:59 PM:

I'm not certain with the Barco projectors, but with the NEC projectors, you have to load the test pattern, then apply the various screen filed - Lens, Screen, MCGD, etc.

Posted by Marco Giustini (Member # 4544) on 04-27-2015, 11:50 PM:

Dave, what I meant was that the white corrected from the server reads slightly less bright than the white corrected from the projector. Not a huge amount. Obviously there is a big difference between corrected and uncorrected, as you said.

Posted by Ian Freer (Member # 1940) on 04-28-2015, 12:21 AM:

I've noticed the same as Marco;
If I put up a corrected test pattern from the projector (MCGD applied and the Target set as Colour Verification), I get 314 x 351 at X fL.
Then play the Dolby FS White from the server, I still get 314 x 351, but at about 2fL less than directly from the PJ.
Is there a particular reason that anyone is aware of for this?

Posted by Marco Giustini (Member # 4544) on 04-28-2015, 06:37 AM:

I thought it was less than 2fL but it may be. I believe there is a contrast control in the ICP, never played with that. But it would make sense for the FS patch from the server to provide the same value.

Posted by Steve Guttag (Member # 268) on 04-28-2015, 07:01 AM:

Justin...for the NEC projector, I suggest you acquaint yourself wit the TI ICP/Enigma program.

You can then apply the test pattern via the TI program and not have to put up with NEC's quirk of always popping you back to full-screen. In fact, I find myself using the TI program for setting screen files and sometimes MCGD files too.

Posted by Justin Hamaker (Member # 2165) on 04-28-2015, 11:55 AM:

Thanks for the tip Steve, I will try that next time I work on my screen files.