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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Fix for FCP L&T Gamma Shift?

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Spencer C

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Whenever I bring a clip in through log and transfer there is a noticeable shift in the gamma. It seems that lots of people are having this issues. I was just wondering if anyone had found a fix for this yet or if the best thing to do is to just use redrushes or Red Alert. Any help would be appreciated.
 
I think we are concluding that FCP and Color output gamma 1.8 from the monitor while you work, then apply FCPLUT when you output in Color.

Adobe apps might output to monitor and files with 2.2 gamma, how do other people find this?
 
Gather round everyone and whip out your LUTS.

Whose first?

Or is it on a Pay Per View basis ( :Emoticom Optional: )

A Penny for your thoughts :mail1:


DogDay.
 
I would not be so conclusive about color outputing gamma 1.8 to the monitor. I do not know yet. Since the same clip appears different when monitoring from color or from FCP (through the sdi out of Kona 3).
I think there is also some diffrences if you render QT from dpx in color or you render QT's from imported Qt's and an other diffrence is whether you entered color through send to color from FCP, or EDL, or just simple import of clips. More then that diffrent render setups in FCP give diffrent looks to the clip on the monitor.

Your expirience?

But to keep optimizim in the air I have a fealing that Apple is about to free us from all that this year.
 
I tested it, it works for some of the conditions mentioned above. It is a greate help if you go QT all the way in 8bit.... but as we allready discussed elseware it is not a propper gamma shift but a diffrent spread of black and white values.
 
Evangelos,

In my case, FCP and Color output from Multibridge Pro are the same (on the monitor).
Then apply the FCP LUT in Color then it shifts up the dark area (that is most noticeble) and I guess that is making 1.8 gamma to 2.2?

I might test this with the film lab. At least work with how we are comfortable with FCP/Color/Video Hardware then apply LUT at the end.
 
With FCP L/T and an AJA Kona card, be sure to turn on the 444 Chroma filtering when using a ProRes422HQ sequence. Would that resolve the gamma shift? I have not had the chance to run my material through a scope.
 
According to a recent AJA Kona 3 Support for Red whitepaper:

"Like REDCODE proxy files, these Apple ProRes 422 (HQ) files generated via the Log and Transfer process are assigned HD video values by default, resulting in a Rec. 709 HD video color space with a gamma of 2.2."

It might be worth it to try Scott's suggestion above. Also be sure that your monitor is set to displaying gamma of 2.2 to match the video clip values.

For more info on this last point --- see this older thread: http://www.reduser.net/forum/showthread.php?t=23625&highlight=gamma+shift&page=5
 
I don't think color sampling depth changes gamma values but worth trying.

From my gathered information, we just have to wait until Snow Leopard and QT X come out to be really correct.

My belief before was that when you use extra video hardware then you can get whatever gamma values from that hardware. But in FCP and Color, that doesn't seem like the case. So even Snow Leopard and QT X support native 2.2 but then what will happen when you have to mach to DCI 2.6 gamma?
 
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