Gamma in Color does not Match FCP Gamma

[Steve MacMillan]

Have you written the Apple engineers about this?

There is also a pretty fundamental math error in the way the Color applies Lift, Gain, and Gamma. (I don't know if Graeme or someone else is going to stomp all over me. I can't believe I am the first person to notice this. So maybe I am all wrong.)

The correct formula for Lift, Gain and Gamma is:

Result = ((Value + Lift) * Gain) ^ Gamma

Applying Lift in Color should cause the histogram to shift to the left and right without changing shape which is what it does.

Applying Gain in Color should not move the left end of the histogram, but should cause the histogram to spread out towards and past the right end of the histogram. This is not what happens. The histogram grows from some point off the left side of the histogram. This indicates that Gain and Lift are being applied in the wrong order.

Similarly, applying Gamma in Color should not affect the right or left sides of the histogram but should only move the middle of the histogram. Again, however, this is not what happens. Both the left and right edges and the gain seem to be affected.

As near as I can tell the actual formula in the program is something like:

Result = Value ^ Gamma * Gain + Lift.

Unfortunately, while this should be a pretty simple bug to fix, it is also going to be very difficult to change since it is going to completely invalidate every color correction ever done.

 

[Elyse]

I've found when I export RED footage from FCP, it crushes EVERYTHING. I found it was when I used the appleprores codec.

Animation codec kept the color and quality. I suggest using that instead.

 

[Kaku Ito]

REDCINE-X's ProRes4444 rendering is consistent through the monitoring in REDCINE-X, then render out on FCP then sent result on Apple Color.

 

[Jim Collins]

Yes, it has been reported.

Yes, it has been reported.

Have you written the Apple engineers about this?

Yes, I submitted a bug report several days ago. And Apple does actually act on them. I submitted a bug report about a year ago concerning a bug in the RGB histogram. The Blue Histogram was actually the Red Histogram over again. My guess is that when the original programmer wrote the program he wrote the red part, then used copy and paste to create the green and blue code sections. He remembered to change the green histogram to display the green data but then forgot to change the blue. Apple fixed it in the last big update about 6 months ago.

 

[Luis Otero]

Update?

Update?

Hey there,

Any update on this so disturbing and abnoscious issue. Please, advise. No Kona, just a BM Intensity Pro for monitoring. :yikes: