The Great Gamma Problem

I and several other people complained bitterly for a long time that the Mac insisted on adding gamma/brightness conversion to stills imported into a Final Cut project that wasn't applied to a movie. So the exact same still imported as a QT and a TIFF would look very different on the timeline.

I also know that one of the versions of Final Cut had a selector where you could prevent that gamma boost.

What version and where is the control panel?

Koz

Are you talking about the gamma level property that stills have? It's trivial. Just open up the item properties window for any still in the browser and put in whatever gamma value you want. You can context-click to get a menu that lets you choose from 1.8, 2.2 and 2.22.

The "default default," if you know what I mean, is "source," but since many stills don't have a gamma value encoded into them, Final Cut has to make an assumption. If you want it always to assume 2.2 or whatever, you can set the default gamma value under the editing tab of the user preferences window.

Be extremely careful about "would look very different on the timeline," though. Make sure you're only comparing how things look on calibrated broadcast reference monitors. The gamma curve of a computer screen is different (by design, and also by engineering tolerances) from the gamma of a television. If, just to pull a crazy example out of thin air that could never happen in real life, your graphics guy complains at you because a shot doesn't look the same on your expensive, carefully calibrated broadcast monitor under typical living-room lighting as it looked on his on-sale-at-Best-Buy computer monitor in a dark room, it's not really the software's fault.

FCP always assumes that all RGB based sources are created with a gamma level of 1.8, and applies a gamma correction to allow it to fit seamlessly into the video gamma of 2.2.

Select the clip in timeline, apple 9, select "Gamma level", change from "source" to 2.2.

If you're going to be doing this a lot, go to User Preferences, under the "Editing" tab, "imported still/RGB Video gamma", switch from source to 2.20.



www.strypesinpost.com

No, it's much more serous and straightforward. I created the slate frames for the company and they have gray scales and color patches, etc. etc. If I create a QuicKTime in one of the linux machines and pull that into a FCP project and also pull in the original TIFF still, the still will be significantly brighter than the movie. This error used to have its own web site where I took waveform stills of all the errors. Known problem, and it appears on an NTSC monitor.

The errors get stuck and appear on a DVD burned from the project. We have a broadcast waveform monitor on the DVD player

<<<Just open up the item properties window for any still in the browser and put in whatever gamma value you want. You can context-click to get a menu that lets you choose from 1.8, 2.2 and 2.22. >>>

Where? Be very specific. Edit > Item Properties....

What version of FCP?

Koz

<<<FCP always assumes that all RGB based sources are created with a gamma level of 1.8>>>

Which Final Cut do you have?

Koz

Unless I totally misunderstand what you're talking about, that's not actually a bug. That's correct behavior.

The TIFF file format does not store a gamma value within it. Instead, it has an optional LUT that maps values for red, green and blue. This is usually omitted, but even when it's present, it's not possible to look at the embedded LUT and extract a gamma value from it.

The default gamma value for a computer monitor, historically speaking, is 1.8. This is in contract to television, where it's 2.2. But 1.8 is merely the default gamma for computer monitors. It's not universal. Your Linux computer, for example, might have a gamma of 2. Or 2.2, or 2.4, or 1.9, or whatever the hell. Nobody has the foggiest idea what your gamma was, because it's not carved in stone the way 2.2 is for television.

So all Final Cut can do is (a) make a guess, and (b) give you the opportunity to correct it if it guesses wrong.

Now, you might not actually be talking about gamma. You could be talking about RGB-YUV conversion and tonal mapping. If 255 RGB is meant to be white, then it should map to luma 235 (in 8-bit, obviously; I can never remember the numbers for 10-bit or higher). But if 255 RGB is meant to be superwhite, then it should map to luma 255. Again, Final Cut has to guess at this, and it gives you the option of changing its interpretation.

(It's even uglier, since Apple decided to change the monitor gamma from 1.8 to 2.2 in 10.6. I get why they did it, but seriously, guys.)

Macs traditionally have a gamma of 1.8 (until Snow), PCs are somewhere in the region of 2 to 2.2, depending on the mood.

So basically FCP will assume it's 1.8. Yea, I just wrapped a project where I had to roundtrip to AE on PCs. Everything comes back bright, so I have to drop the gamma to 2.2, because there wasn't gamma correction anywhere along the lines, and when the video finally comes back as Animation, FCP assumes it's 1.8 gamma and compensates for it.

I'm on FCP 6, but I think you can switch the gamma in FCP 5 or even 4. One format that doesn't allow you to switch gamma interpretation, is a Png QT file. Convert that to animation, and you're cool.

To toggle white level, click apple 0, under video processing tab, select "interpret maximum white as white". This option, I recall had different meanings in FCP 4 and earlier (or was it some version of FCP 5).



www.strypesinpost.com

<<<I think you can switch the gamma in FCP 5 or even 4. >>>

No. I'm here to tell you that 5.0.4 has no such controls. The Item Properties panel is a reader. No controls at all. So between 5.0.4 and 6.0, they put the knobs in no doubt due to our constant complaints.

We will shortly be delivered many hundreds of carefully numbered TGA files which we will prepare into terrific looking videos for application to DVD. And they will all be too bright. I remember trying to figure out a manual conversion in the gamma tools and I never got better than just OK. I don't even remember where the research is now.

So this is me looking for somebody to write a check for an upgrade.

Koz

[oops, sorry....didn't see the later post]
Just butting in here, but how does the change in gamma in Snow Leopard factor into this? I believe the whole system went from 1.8 to 2.0 with SL, no?

FCP 7.0.3, PPro CS5.5, MPro Octo 2.8, 16 gigs RAM, Matrox MXO2, Sony EX1

Quote

We will shortly be delivered many hundreds of carefully numbered TGA files which we will prepare into terrific looking videos for application to DVD. And they will all be too bright.

Okay, come on. I'm as much a fan of breathless hyperbole as the next guy, but the preference is right there. You can change the default gamma assumption from source to 2.2, or to any arbitrary value you want. Yes, that only applies to stills that you have not yet loaded into Final Cut, but really, what else is Final Cut supposed to do? It can't tell what the artist's monitor was set to when the file was created!

EDIT: Aw, crap. Sorry, Koz. I totally misread your post. You're saying that you're currently using version 5.whatever, and the gamma interpretation preference is not there, right? My bad, man. I apologize.

Quote

Just butting in here, but how does the change in gamma in Snow Leopard factor into this? I believe the whole system went from 1.8 to 2.0 with SL, no?

I'm not positive that they changed it. I read long ago that they were planning to change it to 2.2, but I can't swear that actually made it into the release. I'm still on 10.5 here. But if they did change it, it doesn't affect Final Cut. Final Cut's gamma-value assumption is not linked to the operating system or to your display. I think if you go into the System Preferences you can find a way to change your display gamma to, like, four, or some other unusual value. This doesn't affect Final Cut at all.

No, the preference is not right there which is why I wanted everyone to reveal their version number. Somewhere between 5 and 6, they put those controls in -- which I would kill to get.

I warned the engineering group I was going to come looking for dollars and it was too late to call in sick.

Koz

I didn't work on 5.0 at all. I skipped that number between 4.5 and 5.1. Just as a last check before we write this off, to change the gamma source, you right click on the word "source". It's not an obvious changeable option.



www.strypesinpost.com

<<<right click on the word "source".>>>

Good to know. I'll try it when I step into the shop again. Thanx.

Koz

<<<I'll try it when I step into the shop again.>>>

Zippo. Nada. Right or Left Clicking on Source only gives me confirmation of the filename of the still. No control panels.

So that's our upgrade path.

I did think about this a bit in the shower (some of my best work...). That's how to control the gamma of an item. I have 764 items -- a numbered TGA still collection. Now what?

Koz

Make sure you're looking in the right place. The "Source" field is up at the top of the item properties window, but lower down there's a "Gamma Level" field, with "Source" as the default value in that field. If you click where it says "Source" next to the "Gamma Level" label, you can put in an arbitrary value. If you context-click, you get a pop-up with 1.8, 2.2 and 2.22.

If that feature's not there in 5.whatever, then it's not there, but at least make sure you're looking in the right place for it. Or maybe pop up the PDF of the manual and search for "gamma?" It comes up as the second or third relevant reference in the version 6 manual.

As for your numbered sequence, as I described up yonder, go into your user preferences, look in the editing tab and change the "Imported Still/RGB Video Gamma" to whatever you want. By default it's "Source," but you can change it to 1.8, 2.2 or 2.22, or "Custom," which is any arbitrary value. That's the gamma Final Cut will use for newly imported stills forevermore, or until you change it again. (This feature may or may not be in version 5.whatever.)

<<<lower down there's a "Gamma Level" field>>>

Not for me, there isn't.

<<<user preferences, look in the editing tab and change the "Imported Still/RGB Video Gamma" >>>

I would if I had that setting.

I think this was the FCP right before they did all that business with the extra tools. I like to think that my web page with all the Final Cut gamma errors published had something to do with it. I since took it down, but we never got the program update to gain the extra tools and found it relatively painless to work around it...until now.


The current work-around is to import the still sequence in QuickTime Pro and export an uncompressed movie. Pull that into Compressor and etc, and etc. That's seems to be a relatively benign pipeline, and the production people seem to be pretty happy with the results.

OK, less unhappy...

Koz

You realize the upgrade to Final Cut 7 is only $300, right? It sounds like you're wasting more than that just running that workaround of yours once.

I mean, the correct zero-cost workaround is to have your graphics guys work in gamma 1.8. If they're working in a different gamma, then all the format changes in the world aren't going to help you.

<<<You realize the upgrade to Final Cut 7 is only $300, right? >>>

Plus the cost of the Intel Macs to run it...

<<<have your graphics guys work in gamma 1.8.>>>

Our Movie guys already work in oddball gammas and colorspaces. We were thrilled to find any pipeline at all that worked. We got around the 24.00/23.976 thing with the Targa Sequences. The machines seem to be relatively OK with that. Fortunately, we don't need sound...yet.

[sigh]

Koz

We're not completely hopeless. We're on the budget trail, especially given the recent problems. I have meetings with people trying to shift dollars around to do upgrades back here. The machine with the gamma problems is the "modern" machine.

Koz

>You realize the upgrade to Final Cut 7 is only $300, right?

Hmm... Get FCP6?



www.strypesinpost.com

I'm not a business whiz by any stretch of the imagination. But from talking to business whizzes, I've picked up on the magic of depreciation.

Let's say a brand new Final Cut-based edit room, suitable for onlining, costs around $25,000. That number's really approximate; that's what I paid for the two I built last year. What I understand from the business guys is that that expense is really easy to absorb, because everything in that room depreciates, and you can put that depreciation down on your taxes. It reduces your taxable revenue like a deduction, which in turn reduces your tax burden. So you spend a chunk of money now, then take a part of that chunk off your taxes for the next five years (three years? I forget), so the actual cost over time is much lower than it seems.

Accountants know about this stuff. I only know what I'm told. But it's worth looking into, if you're having trouble justifying capital investment.

Of course, that only works if your company actually has the cash to spend. If you're in a very tight liquidity situation, that might not be an option, which would suck tremendously.

I say again: Make your graphics guys work in 1.8. They should have been doing it already, or at the very least coordinating with you on issues of color space, dynamic range and nonlinearity.

<<<Of course, that only works if your company actually has the cash to spend. If you're in a very tight liquidity situation, that might not be an option, which would suck tremendously. >>>

We're moving into a new building and The Movies is not known for its regular paycheck.

We did get a pipeline to work, so the production people are happy and I'm on the radar for new machines. We had the older one go down a bit ago and it took three of us to bring it back up. I told everyone I can't support this machine anymore. The next time it goes down that's the end of the story, so make sure your work is backed up.

Koz

Tip for next time around the purchasing maelstrom: Put a lifespan on your capital equipment. Say "We're going to buy so-and-so many systems with such-and-such specs, and use them until July of 2014, when they'll be fully depreciated. At that time we'll replace them, and we anticipate that the overall budget for capital outlays at that time will be $XXX,XXX." Then update that capital equipment plan annually.

Sorry if this stuff is elementary. I had to learn it the hard way, 'cause I'm dumb, and I have this natural tendency to assume everyone else is also dumb like me, so I get all excited and share.

I think someone in accounting actually keeps track of stuff like that, but I suspect at the end of the depreciation period, it merely becomes a "free" machine or a machine we don't have to buy or rent.

I know the end date of the depreciation period is supposed to be the end-of-life date...

Koz

Quote

I suspect at the end of the depreciation period, it merely becomes a "free" machine or a machine we don't have to buy or rent.

Got that backwards, I'm afraid. When the asset's fully depreciated, you can no longer deduct a fraction of its original purchase cost from your taxes. So at the end of the depreciation period, your tax burden goes back up to where it was before you bought the asset. In a very real sense, the end of the depreciation period is where you have to start paying for it, 'cause you lose that deduction.