FORUMS: list search recent posts

scope discrepancy

COW Forums : Flanders Scientific

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Robert Arnold
scope discrepancy
on Feb 10, 2011 at 7:48:56 pm

I asked this question in the Color forum, and someone there suggested I try here also:


I'm working through Steve Hullfish's excellent book, The Art and Technique of Digital Color correction. I've just started doing tutorials, and I'm noticing that the scopes in Color and the scopes on my FSI monitor (connected via a Kona LHi card) don't agree when I work with files from the tutorial. For example, when I have grayscale_neutral.mov loaded, the scopes in Color match what's shown in the book (with all three colors in the parade sitting nicely on the 0 line), but on the FSI scopes all three channels are crushed well below 0, and the highlights stretch higher than they do on the Color scopes. The discrepancies are on the order of 5 IRE in both directions. I haven't had this problem when working with any of my own footage. Any ideas what might be going on?

Thanks!


Return to posts index

Bram Desmet
Re: scope discrepancy
on Feb 10, 2011 at 9:16:58 pm

Hi Robert, the monitor's scopes show you what you are sending, it is that simple. We don't manipulate the signal at all before going to the scopes so what you see is what the monitor is getting...So I would check your settings on the editing system or output card. A very useful tool is the measurement feature on the monitor which allows you to measure a specific point on screen to get exact RGB and IRE measurements, this may help diagnose the issue with your setup on the computer side of the equation.

Bram Desmet
FSI (Flanders Scientific, Inc.)
http://www.FlandersScientific.com


Return to posts index

Bram Desmet
Re: scope discrepancy
on Feb 10, 2011 at 9:40:01 pm

one other thought...can you bounce the same footage to FCP and see if you get the same results?

Bram Desmet
FSI (Flanders Scientific, Inc.)
http://www.FlandersScientific.com


Return to posts index


Robert Arnold
Re: scope discrepancy
on Feb 11, 2011 at 2:04:35 am

I sent it back to FCP, and the scopes on the FSI (viewing via FCP) look like they should. So the question is: why is color sending a different signal to the display?


Return to posts index

Erik Lindahl
Re: scope discrepancy
on Feb 11, 2011 at 10:53:46 pm

This might be off the bat but as as I know Color works in RGB where FCP in general works in YUV. Color output will be converted at some point from RGB to YUV and it COULD be this conversion is done wrong on your setup (i.e. the scopes show your "raw" color information).

Try changing your Kona settings under I think "codec" in their control panel and make sure they are correct. As look through your Color settings if anything is off there. Last but not least try outputing from other apps such as After Effects (if you have that) or the AJA TV app and see if your output differs.

But I could be off the bat here as stated.

------------------------
Erik Lindahl
Freecloud Post Production Services
http://www.freecloud.se


Return to posts index

Robert Arnold
Re: scope discrepancy
on Feb 13, 2011 at 3:56:22 am

Well, here's what I've discovered: If the shot is in the Animation codec, there will be a significant difference in both the image itself and the resulting scope readings between Color and my external monitor. The image that is getting sent out is *significantly* more contrasty, by about 5-7IRE on each end. If I take the same shot, transcode it to ProRes, and bring that into color, the image and scopes match perfectly between color and the external monitor. Similarly if I take a shot that was originally in ProRes and transcode to animation, it will exhibit the aberrant behavior.

I looked under the AJA codec tab, but the only enabled option was Gamma, and this setting did not seem to have any effect. (It was under "YUV - RGB Conversion".)

I tested with AJA TV, and the two shots codecs appear (and scope - can that be a verb?) exactly the same, so this would seem to me to be a definite Color bug.

My setup: Mac Pro (2009), Color 1.5.3, Kona LHi, FSI 1760.


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]