Calibrating for video accuracy

[Chris Soucy]

Well, I'm sure Sareesh can tell us.

Don't pretend it means anything to me either, but they're beutifull screens.


CS

[Josh Bass]

Sareesh melted my brain. I'm still reading that if you intend folks to see stuff in 709, that's the space you should grade in. Which brings us to the issue of LUTs for monitors in other color spaces. . .so if working with an sRGB monitor, how do you apply those? Is it through the CC software or an i/o box or something else?

[Sareesh Sudhakaran]

Originally Posted by Josh Bass

Sareesh melted my brain...

Well, I'm sure Sareesh can tell us.

All right, you asked for it!

In traditional science, whenever you see the term 'Delta', it means 'difference' or 'deviation'. If I have seven cups to my left and three to my right, my cup-delta is 4.

In the image Chris has scared us with, Delta-E shows how each color deviates from the 'perfect color space' value. Every monitor, even the most expensive ones in the world cannot reproduce a space perfectly.

Color space is theoretical. The color space of the human eye is CIE XYZ, but even the eye cannot see all the colors in this space!

The Delta-E of the human eye is about 1. The best color grading monitors should have a Delta-E of less than 3. The Delta-E of the Ultrasharp is about 4, which they represent as <5 for both sRGB and Adobe RGB.

Delta-E has many variations, this one was ratified in 1994 by CIE so it's called DeltaE94.

So bottom line, the graph shows us that the Ultrasharp is better than consumer grade monitors, but not as good as the best monitors on the market - but we already know this, right?

The bottom-left graph should be perfectly horizontal, but it is not - I don't think there is a monitor capable of it, so I guess it's pretty good that it manages to be horizontal most of the way.

The bottom-right is just a gamma curve - at 2.2, which is standard. No vodoo here. It does tell you that the display max is at 250 nits (cd/m squared).

Bottom bottom line? Take all this with a grain of salt. Color graphs are to monitors as sensor megapixels are to camera manufacturers. Don't believe everything you see.

I'm still reading that if you intend folks to see stuff in 709, that's the space you should grade in. Which brings us to the issue of LUTs for monitors in other color spaces. . .so if working with an sRGB monitor, how do you apply those? Is it through the CC software or an i/o box or something else?

Yes, nobody claims any different. Walk into any broadcast studio and all you'll see are monitors in Rec. 709 (assuming they're shooting and broadcasting HD).

But, sRGB = Rec. 709, which makes any monitor that can show 100% sRGB good enough for Rec. 709.

LUTS can be applied two ways: software or hardware.

The software LUT tells the graphics driver/software to skew the data to make things look different. The monitor does not change.

The hardware LUT does the same via firmware living inside the monitor. The panel does not change.

In your case, Josh, LUTs are handled by software. That's good enough, and is the most versatile way to do things nowadays. The cool thing about LUTs is that they don't need a lot of computing power. It's like having a multiplication table in your hand so you don't need to calculate for yourself.

You can create your own LUTs, dump them in the software of your choice - whether it be color grading or editing or vfx - and it just skews the data to show you the space you are working in. A monitor is like a butler. It takes orders from its master (the GPU software) and tries its best. A butler can only be pushed so much.

Working with color profiles and LUTs are not as easy as I'm making it out to be. There's a lot of stuff happening under the hood that you should be aware of. I highly recommend you start working with free software, like Resolve, Red Cine-X, etc. and try to solve one problem at a time. Working in Rec. 709 is the simplest workflow in video - it has been designed specifically for ease of use.

Is anyone still reading?

[Josh Bass]

Gothcha! Still reading.

Anyway, I hate to be "that guy" (confession: I'm ALWAYS "that guy"), but research indicates that while the primaries and white point are identical between sRGB and REC 709, the gamma is different, one is 2.2 while the other is 2.4 (guessing sRGB is 2.2).

So that means we need a way to tell the thing to display with a 2.4 gamma, and can basically leave everything else the same, do our Spyder calibration, and we're good to go, yes? So is altering the gamma a simple thing?


As for getting complicated, no worries; again, I'm not trying to be pro colorist. I just graded (it was a very gentle, conservative grade) my last short with the CC tools in FCP 6, and would do it again if I had to. I now have access to the tools in After Effects and Premiere (though someone pointed out AE doesn't have video scopes, at least not free ones. Boo.), and will start playing with the free version of Resolve soon.

[Sareesh Sudhakaran]

sRGB and Rec 709 are equal color spaces. Gamma is a different thing altogether.

Gamma has nothing to do with color, it is applied on the luminance (Luma) only. When you change the 'color space' in software, the gamma is one of the things which are 'skewed'.

That's because Rec. 709 is a color space, but when used in broadcast it also includes many other things, like resolution, frame rate, gamma, etc. Just like NTSC, which is an umbrella term for color space as well as 59.94i, color, its gamma, etc. Professional software allows you to define gamma independently to color space. Consumer apps do not - they just provide 'presets'.

All this is nothing - the difference between 2.2 and 2.35 (the broadcast standard), or 2.4 (the rounded value) is not beyond the capability of any monitor, consumer or professional. A bigger jump is a gamma of 1.8, which Apple displays had pre-2009, and that caused a lot of problems.

Both sRGB and Rec. 709 are color spaces designed from the ground up to work equal to one another. They knew that one day HDTVs and computer monitors will probably use the same technology. Hasn't that turned out to be true today?

To answer your question: Altering gamma is a simple thing. Especially if you're working in professional software like Adobe's or Apple's or whatever. It can take care of everything under the hood so you can keep working, or it gives you the power to make your own variations, through color profiles or LUTs.

The GPU software just takes orders from your app and skews the data and passes it on to the display.

If your display is capable of 100% sRGB, and is calibrated for it - it is more than capable of working in the Rec. 709 color space for all practical purposes.

I just burned a 100 calories...

[Sareesh Sudhakaran]

You're going to love this discussion: What's your display gamma?

Take a look at the last question, after everything that was discussed...

[Josh Bass]

Ha. Oh well. I've done it, on this forum even. like recently.

Anyway, if anyone's interested, apparently there's a known issue with the newer ipads where the screen on some of them is either noticeably yellower than what looks "white" overall, as in, the white balance is off, or there will be portions of the screen that are like that . . .like the one i just got, where the left side (in portrait mode) has a noticeable yellow cast to it. some folks say this has something to do with glue that hasnt quite set yet and the problem will self-correct in days or weeks or months, some say it never changes. No one conclusively knows what the issue is or how to fix it other than exchanging ipads 'til you get a "perfect" one. i'll give this a few days and see what happens. leaving the brightness maxed and leaving the ipad on all the time with something pure white displayed is supposed to help.

long story short, if you had the idea to get and use the ipad to proof stuff for your photo or video work. . .good luck.

[Josh Bass]

Let's go at this from another angle. . .

If one was to get an actual plasma TV to use rather than a computer monitor, which kind would you recommend? Does it need to be the higher end Panasonic Pro series (I think these are in the $2000-2500 range), or would something "lighter" do? Would any of the i/o boxes run to it? I realize with these it's generally advised to have it really and truly calibrated by a professional (i.e. adding hundreds of dollars to the cost), but simply using a calibration DVD or running bars to it can at least get you in the neighborhood

[Eric Olson]

Originally Posted by Josh Bass

Let's go at this from another angle. . .

If one was to get an actual plasma TV to use rather than a computer monitor, which kind would you recommend? Does it need to be the higher end Panasonic Pro series (I think these are in the $2000-2500 range), or would something "lighter" do? Would any of the i/o boxes run to it? I realize with these it's generally advised to have it really and truly calibrated by a professional (i.e. adding hundreds of dollars to the cost), but simply using a calibration DVD or running bars to it can at least get you in the neighborhood

For digital photography the files will be printed by expensive calibrated printers. For digital cinema the files will be projected by expensive calibrated digital cinema projectors. For videography, the files will be played back on cheap LCD televisions and old CRT televisions. However, people get used to their misadjusted televisions so correctly calibrated video is still important. Moreover, before calibrating your editing monitor, it is important to realize that your eyes are already calibrated to whatever television is sitting in your own living room.

If you are used to purple skin tones and neon green grass, then all bets are off when trying to edit video using a reference monitor. Similarly, musicians who play Hindustani classical music do not listen to western popular music because it would ruin their artistic sense.

[Josh Bass]

My personal experience has been the eyes will acclimate pretty quickly to new things. If you have a properly set up monitor, within a few minutes of looking at it, you'll see everything on it as "right" (providing the material being viewed is "right."), even if you were looking at purple skin tones 15 minutes before.

I have my mac monitor set up with a program called "flux" that changes the color temperature to really warm after sunset. Supposed to be better at letting you feel tired/sleepy when you should, whereas staring a blue monitor is supposed to keep you awake. Don't worry, if it's all BS, it was a free program so I didn't get "suckered." Point is, I barely notice the change, except when I see it happen. After a few minutes, it's just "there."

[Chris Soucy]

I think you're on a bit of a hiding to nothing on this one, Josh.

As I found out when I ventured into HD video, calibrated Hitachi CRT monitor ( a beauty, too), the works.

Stills? No problem, had everything calibrated, it was WYSIWYG, all along the chain.

Video? No matter what I did, I'd go to see where the content was being played (if possible) and discover their screens were all set to "showroom shock and awe" mode, made a mockery of anything I did in trying to balance the colour, the screens simply screwed it no matter what I had done.

In the end I simply shot it all as flat as a tack and left it at that, none of it was heading for broadcast anyway, and even if it was, so many screens out there that only approximate to "true colour" just made the entire process moot as far as I was concerned.

Did I get any complaints?

Nope, not a one, from a soul.

My suggestion, for what little its worth:

Get yourself a (half) decent editing monitor, an UltraSharp Dell will do, and run the finished product by your very own HDTV, set to your own preferences, and see how it looks.

If it looks good, go for it.

Mr and Mrs Joe Average, especially in NTSC challenged North America, would'nt know correct colour if it sat up and bit them.

I was always stunned by the neon/ flourescent TV grass of football games in Canada, well, neon everything actually, thank god for PAL in Europe/ Australasia and elsewhere.

I know, those days are supposedly past, but the punters, unfortunately, haven't, quite yet.

Just my 2 cents.

Regards,


CS

[Josh Bass]

What you say may be true, but the sick neurotic part of me that isn't listening still has pride in his work and wants it to be seen the way he intended it, whether it comes out that way or not based on someone's flawed display. I think the idea behind the expense and effort of proper calibration is that your material, when graded/corrected on a calibrated system, has the BEST chance of looking the MOST correct on the HIGHEST number of displays.

[Sareesh Sudhakaran]

Originally Posted by Josh Bass

Let's go at this from another angle. . .

If one was to get an actual plasma TV to use rather than a computer monitor, which kind would you recommend? Does it need to be the higher end Panasonic Pro series (I think these are in the $2000-2500 range), or would something "lighter" do?

I use Panasonic monitors regularly with the C300. With plasma, I will only recommend the best quality. However, plasmas are disappearing from the marketplace, and I wouldn't invest in one today.

[Chris Soucy]

Josh...............

Unless you're planning on shooting a better version of "Star Wars" or "Lord of the Rings" or some other epic, destined for cinema & TV release worldwide, give the "sick, neurotic" part a swift kick up the ass and just bloody well get on with it (producing content, that is).

No one, I can assure you, will know, but YOU!

Shoot it flat, it'll be cool.

(BTW, if it's going for the afformentioned "blockbuster" category, you need do nothing anyway, that's what editors are for, they do have their uses).

Another 2 cents, this is starting to rack up, much more of this and you'll owe me a beer!


CS

[Josh Bass]

Your beer's in the mail. If you don't receive it in a few days. . .the. . .um. . .mailman took it. That's why he's stumbling and putting other people's mail in your box.

Anyway, I may have found the unholy grail.

We're goin' old school here, but I'm finding a lot of validation for the practically ancient Sony PVM 14L5 (or if your spine wronged you in some way and you want to get revenge on it, the 20L5) monitors for color grading. They are old-timey, "they don't show Howdy Doody anymore, Grampa, jeez! And stop biting my head; it's not a cantaloupe" CRT monitors, 14 and 20" respectively. They take a component input as is, and can be upgraded with an SDI card. Granted, they don't show full HD resolution (at least the 14. . .it's like 800 lines) BUT they do show the proper color space, and are apparently very popular in grading suites. Can show SD too if you're into that, but need to be recalibrated each time you switch back and forth.

These thing are a couple hundred dollars on ebay, WITH the card sometimes, (obviously have to watch for the condition and age, etc.) But this is supposed to be an MC Hammer-worthy legit solution. Except for the tiny screen and ridiculous size.