H.264/QT Gamma Shift/Snow Leopard

[Ben Holmes]

Apple has shifted all system gamma to 2.2 – as has been widely reported here and elsewhere. In theory this should solve many of the gamma ‘bugs’ that have plagued QT for a while.

As I’m not letting Snow Leopard anywhere near a work machine yet, I’ve yet to see the evidence with my own eyes – others say it’s much improved, although I’ve also read some talk of gamut problems and colour shifts that may be related to driver issues. Again – I’d hold off a while until this is all shaken out.

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[Mark Lea]

I did some tests this morning with Snow Leopard and FCS1, and the gamma “bug” is still there when I encode H.264 clips from multiple sources. I tested an HDV clip, an Apple Intermediate clip, and a ProRes 422 clip. All encodes still look color shifted, and desaturated. I wish I understood this problem more, so I could understand why it is doing this, and how to correct it.

In other gamma related notes, I’ve noticed that the new gamma affects the Canvas in FCS1 (I assume the same would go for FCS2 as well, but I haven’t installed Snow Leopard on my production machine yet). As I’ve read elsewhere, the Final Cut Pro canvas is adjusted to reflect a 2.2-like gamma, when viewed in a 1.8 gamma environment. Now that 2.2 gamma is native in Snow Leopard, the same adjustment in Final Cut Pro is still there, making the Canvas video window darkened, and more contrasty. Is anyone else seeing the same thing?

Here’s how I tested it: On my Leopard machine, I placed a captured HDV clip in a sequence and viewed it in the canvas video window. I then opened the same clip in QuickTime, and viewed the windows together. Both windows displayed pretty much the same color and contrast.

On my Snow Leopard machine, I did this same process, and the canvas viewer was much darker than the QuickTime window. I opened the clip in both QuickTime X, and QuickTime 7.6, and had the same result. I’m highly confused.

[Thatcher Kelley]

I am having the same problem with Snow Leopard. If someone has the solution to this or an answer, let me know.

Thanks,
Thatcher

[Dean Isaacs]

Apple has a new support page which addresses gamma 2.2 in snow leopard.

Here is the link. https://support.apple.com/kb/HT3712.

This has me thinking: Perhaps it’s not the “values” that are being desaturated, but its the information code about how to display those values. Caution #1: I may have no idea what I’m talking about.

But a few things started me thinking this. (i) I have read in scattered places on the web that there is a “gamma tag” that causes the gamma shift and (ii) the above support page suggests that it is possible to open a Movie in Previews and using the Tools menu change the Color Profile. I don’t know what the correct Color Profile would be, if this works at all, but maybe this might work. I will try it when I get in front of a snow leopard system running fcs 3.0 –maybe at an Apple Store.

Caution #2. The support page says chaging the color profile is NOT reversible, so only do this on a copy of a movie or oe a movie made just for this experiment.

Dean Isaacs

[Anthony Dalesandro]

One of the things I do is in Compressor in the Inspector palate in the Filters button under the Color tab (phew) I change the Default for Encoder to Preserve Source. That seems to keep the color in check. Then under the Video tab a add a Gamma Correction filter of 1.07 to 1.12 depending on how dark the source footage is. This keeps it from getting milky.

This is my FCS 2 under 10.5 method. Haven’t upgraded to either FCS3 or 10.6 so I don’t know how effective it will be then.

—
Anthony Dalesandro
anthony@anthonydalesandro.com
https://www.anthonydalesandro.com

[Dean Isaacs]

Back from the Apple Store, where I tested on fcs 3.0 and Snow Leopard. Nice way to kill lunch.

1. Can’t use Preview to change color profiles on video. Preview doesn’t open videos. So much for an elegant fix.

2. Although I couldn’t figure out how to change the color profile of an existing movie, when you export using quick time conversion under options > filter you can choose another color profile. Some of the profiles make the colors look staturated again. But I don’t know if this is a rendered filter or just a different color profile tag. Interestingly, no matter what color profile is chosen in the filter menu, when I play the movie in QT X and use the get info, the color profile info is the same, “HD (1-1-1)”–whatever that means.

3. I know I can adjust the gamma in compressor. But if ones does this and Apple ever fixes this problem in QT, the “corrected” files may no longer display correctly.

4. Way too complicated for my small brain. Typical Apple. Beautiful products with irritating flaws they won’t bother to fix.

Dean Isaacs

[Ricardo Guerreiro]

This has worked with FCP7 and OS10.6 although for my particular footage I used a gamma correction of 1.20. And still there are people who say Apple takes this Pro Apps thing seriously!! I can’t believe I would find yet another one of these silly flaws. One pays 1000€ for a “pro” suite to then have to slove simple things with workarounds. Me and quite a few other people are still waiting for the “non-english” keyboard to work properly with FCP. I wonder how difficult that is for Apple to fix….

[Ricardo Guerreiro]

When I said “this” in the above post, I meant the procedure described by Anthony Dalesandro. I thought my answer would be just bellow his post.