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FCS Inconsistent Gamma Shift Issues
I’ve been following message boards for the last couple years following the various Black Level and Gamma issues associated with Macs and the FCP workflow. I’ve found work-arounds along the way, usually involving adding Gamma filters during certain steps to compensate for this issue. My company is encoding a massive amount of media now, however, and it’s about time I understand WHY Apple programs have these inconsistencies.
I’m quite aware of the 2.2 Gamma adjustment in FCP. My issue is not how FCP views content, it’s how it exports it. I was under the impression that even though the FCP monitor adjusts the Gamma, it exports the footage the same as it comes in. This is often true, but I’ve come across a situation that just doesn’t make sense…
I import an AIC clip into FCP. If I then immediately export that clip, and then compare the resulting AIC to the original AIC, the new export is washed out (1.8 Gamma vs. the original 2.2 Gamma, perhaps.) BUT, if I apply a filter to the clip and then export (forcing FCP to render the timeline) then the resulting clip is identical to the original! This happens when the filter does nothing, for example, applying the Gamma Correction filter at 1 (no change).
The same thing happeneed when dropping a telecined AIC into Compressor and then reversing the telecine. The resulting clip is a washed out AIC. It’s not changing compression formats, why does it do this?
I can deal with problems and oversights, but inconsistencies will be the death of me, since I can’t create a batch process for everything, and I’m growing very tired of compensating for these brightness issues.
I’m using FCP 6.02, Compressor 3.
Side note: if I drop the resulting washed out clip into Quicktime and check the new ‘Enable Final Cut Studio color compatibility” in prefs, it corrects the Gamma and is no longer washed out. But, then it won’t correctly display other clips that aren’t washed out (it darkens them). If I drop the washed out clip in MPEG Streamclip, it looks fine.
So, I can deal with the washed out clip, but only if every clip coming out of FCP is the same, which is not the case.
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3 Replies
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I stumbled on this thread in search of other exporting issues, and thought I’d drop my 2 cents in what I’ve found in my research. I’ve noticed the biggest problem is in a chroma shift rather than just a gamma shift. I put Macs digital color meter on bars that were in FC6 and then on a variety of exported clips including a reference clip, a self contained movie (all with the same sequence settings, a flip 4 mac export from FC6, H264 etc. What I discovered was that the green percentage values were going up by almost 20 percent while the Red and Blue values were only shifting up by maybe 2 to 5 %. This is clearly not just a gamma adjustment. In fact the gray bar only changes by 2 % as well, which Im sure is just the gamma shift But still that is with FC gamma compatibility checked in QT. So where is this DRASTIC GREEN SHIFT coming from? I’m Baffled, because there is really no work around for this, there is no color management in FC like there is in say Adobe programs, or what have you. I’m guessing that perhaps working in YUV colorspace may have an effect on the RGB color meter readings, but with a 20% shift up in Green Value, I’m guessing there is more to it than that.
Any workarounds or advice would be much appreciated.
Thanks,
Chris Wiegand
http://www.stonekap.com -
And as a follow up – what determines how Apple tags their videos with the correct Gamma? I’m looking at two videos in Quicktime right now, both exported from FCP, and when I click the “Enable FCS Color Compatibility” box, one video darkens, the other doesn’t.
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Correction: It seems like only videos exported from Compressor shift Gammas with the box checked or not checked in Quicktime. FCP seems to stay steady. Any idea why Compressor does this and if any other programs produce this result as well?
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