Calibrating for video accuracy

[Josh Bass]

Ok I just realized what I wrote up there and now I feel like moron.

So the Ipad obviously won't play 10/8 bit uncompressed, so you'd have to save your test files in a format it can work with, and deal with any resulting gamma shift. Like I said, definitely a poor man's solution.

[Ivan Castell]

Originally Posted by Josh Bass

Ok I just realized what I wrote up there and now I feel like moron.

So the Ipad obviously won't play 10/8 bit uncompressed, so you'd have to save your test files in a format it can work with, and deal with any resulting gamma shift. Like I said, definitely a poor man's solution.

Yes, not ideal but it should work from what I do (not high end broadcast stuff).

My only solution it's to get an original MXO (that's what i'll do + the HP Dreamcolor), but I still wonder if anyone knows if CS6 or other NLE can deliver a YUV to RGB accurate signal to an accurate monitor and you can trust it. Apparently CS6 is able to do that (Speedgrade?, AE?). Don't know about avid. It's not that I want to avoid buying an I/O card, but looking in the forthcoming 2-3 years that I won't upgrade my computer it'll be nice to know if we really need it for NLE/Color correction apps that the hardware don't support it.

[Josh Bass]

Boo. Eyeball compared ipad mini and regular by pulling up the same color chart on both via google image search. Colors definitely dont look the same; mini's desaturated/washed out compared to full size. Maybe thathats only the new full size ones with the retina display that look that different; no way to tell (i did this at microcenter).

Researching online confirms, saying that mini displays 62% of full color gamut.

[Eric Olson]

Originally Posted by Will Thompson

My understanding was that even if an HDMI monitor receives a YUV signal, most will still convert to RGB before displaying anyway.

Right! The CRT and LCD display technologies used in all televisions and computer monitors create color using red, green and blue additive primaries. If you look with a magnifying glass at any screen you will see these primary colors, either as dots or vertical stripes. The choice reflects human physiology: the eye has three types of cones that are sensitive to three different wavelengths of light--red, green and blue. Therefore, at some point, YUV must be converted to RGB in order for us to see the colors.

Accurate video monitoring involves calibration and correct viewing environment. Calibration is a result of software, firmware and hardware working together in a predictable way. A trivial mistake is when the difference between full and studio swing levels create what is sometimes called a gamma shift. PC systems can be configured in so many ways that it can be complicated to ensure an BT709 transfer function when displaying video. Macintosh computers are less configurable and therefore easier to calibrate. However, there is almost nothing to configure with a reference monitor directly fed by a YUV signal.

Correct viewing environment is as important as calibration. Computers monitors are generally viewed in well lit rooms while televisions are viewed in darker rooms. In addition, any windows open on your PC desktop, especially windows with black on white text, give off ambient light that affects the perceived brightness and color of the video window. This is why a dark color scheme defaults with most video editing software. Make the video window full screen and pay attention to room lighting.

In the end, your viewers will watch the video using a mixture of CRT televisions, gas plasma displays, various types of LCDs, computers and projectors. Many televisions will still have the vivid picture profile selected from the showroom at a discount store. For the same reason an audio engineer checks how popular music will sound in an automobile, most video should be checked on a variety of display devices. With experience, monitor calibration and attention to viewing environment one gets better at achieving reasonable image levels the first time around.

[Sareesh Sudhakaran]

Originally Posted by Ivan Castell

I'm thinking of buying an HP Dreamcolor (that can work in HD 709 color space) and connect it directly with a displayport cable. Like most people on this thread I've read the provideo coalition post, and if CS6 can really do an accurate YUV to RGB conversion, then I don't see the need for an I/O (for me). I just want an accurate broadcast preview. Does anyone know if this it's true?

You don't need an I/O card only for display. A 10-bit GPU is good enough, like Firepro and Quadro. Displayport is perfectly fine.

And by the way, the conversions from Y'CbCr to RGB and back are clearly defined mathematically, with interpretations left to the user (you). If a manufacturer cannot do it correctly, they've made a simple math mistake. I have yet to see this in reality. If you're having color problems, or have heard of problems by other people, then something else was wrong.

Most consumer grade monitors can display 90% or more of Rec. 709 (sRGB), but a broadcast monitor should be capable of 100% - otherwise what's the point of spending extra?

[Josh Bass]

I thought I read that the Dreamcolor needed a specific something something kind of input to activate its something something engine, otherwise you wouldn't be taking advantage of the color accuracy it's capable of.

What consumer monitors are you referring to? I would happily take 90% accuracy over 0%, which is what I have now.

[Sareesh Sudhakaran]

Originally Posted by Josh Bass

I thought I read that the Dreamcolor needed a specific something something kind of input to activate its something something engine, otherwise you wouldn't be taking advantage of the color accuracy it's capable of.

What consumer monitors are you referring to? I would happily take 90% accuracy over 0%, which is what I have now.

Ha Ha! 0% as in switched off? You just need to switch it on.

If you're serious, the

ASUS PB278Q

 

ASUS PB278Q

and Ultrasharp series (the cheaper ones) easily reach 100% sRGB, which is about 72% NTSC. Most monitors above $1,000 should do 100% sRGB and Rec. 709 easily. This is more than enough for broadcast work HDTV mind you, not NTSC or PAL.

The monitors more than $1,000 aim to get 95% or more of Adobe RGB, which is wide gamut. If you're going cinema quality, you'll need a P3 based projector. The 'cheaper' cinema monitors are close, but not good enough. By cheap, I mean the most expensive ones by Eizo, NEC, Dolby, etc.

No, the Dreamcolor doesn't need anything extra. I confirmed that two years ago with HP and Nvidia. All it needs is a GPU that delivers 10-bit. Unless they lied...

Wish you and everyone else a happy new year!

[Josh Bass]

My mistake on the dreamcolor, then. Maybe I'm thinking of what I read/heard about why it didn't make a good FIELD monitor.

I was being somewhat facetious about 0% accuracy, but I really am using an SD 13" CRT Sony production monitor hooked up via firewire and calibrated to color bars from my NLE to judge color at this time, which is wrong on many levels.

When you distinguish between NTSC and REC 709 (e.g. this monitor is good for REC 709, but not NTSC), are you talking about SD vs HD?

This would be for use on my personal projects (I don't offer myself professionally as a colorist) to myself piece of mind that on those rare occasions when I have a screening (festival, event etc.) or something, I'm sending out an image that looks how I think it does. So not broadcast, not cinema quality.

Everything I've read says that any computer monitor, no matter how nice, unless it's able to be calibrated to the 709 colorspace, is no good for that type of color correction. So that would be your Eizo, dreamcolor, etc. The rest are good for the RGB colorspace only (i.e. computer/web stuff). So now we're left with the $2500+ monitors like TV Logic, Flanders, etc., or some plasmas. And even those monitors are no good unless professionally calibrated (i.e. by someone who does it professionally for a living, not by you or me).

Did I get all that right?

[Sareesh Sudhakaran]

Originally Posted by Josh Bass

When you distinguish between NTSC and REC 709 (e.g. this monitor is good for REC 709, but not NTSC), are you talking about SD vs HD?

Either way. You could assign an HD video to either PAL or NTSC if you wanted to. It sounds weird, but there are scenarios where it's useful. E.g., I am not very experienced with NTSC, but Rec. 709 is very close to PAL, and I remember moving between the two, temporarily, just to make sure my grade would work for both HD and the DVD version. You can't do that with NTSC, though.

NTSC is a better color space overall, compared to Rec. 709, sRGB or PAL. It covers roughly 54% of CIE XYZ, while PAL is about 37% and the other two are 35%. And cinema quality, either P3 or ACES, is about 70%. Don't ask me how I came up with these numbers. It's ugly.

Most monitors are either HDTV or sRGB, and the old broadcast field monitors are still around only because a lot of people are still shooting SD, instead of shooting in HD and down-converting it in post. When you're in such a production, having a monitor with the ability to do both is quite beneficial. But it's getting rarer by the second.

This would be for use on my personal projects (I don't offer myself professionally as a colorist) to myself piece of mind that on those rare occasions when I have a screening (festival, event etc.) or something, I'm sending out an image that looks how I think it does. So not broadcast, not cinema quality.

Everything I've read says that any computer monitor, no matter how nice, unless it's able to be calibrated to the 709 colorspace, is no good for that type of color correction. So that would be your Eizo, dreamcolor, etc. The rest are good for the RGB colorspace only (i.e. computer/web stuff). So now we're left with the $2500+ monitors like TV Logic, Flanders, etc., or some plasmas. And even those monitors are no good unless professionally calibrated (i.e. by someone who does it professionally for a living, not by you or me).

Did I get all that right?

A computer monitor capable of 100% sRGB is good enough for professional, broadcast quality HDTV grading and testing. I have written an article that might shed more light on this: What is Color Gamut and a Wide Gamut Monitor?

But hold on, we are only comparing color space, and nothing else. A high-end Dell ultrasharp is the perfect color space, but it is a consumer device. An Eizo (the higher end ones, the cheaper ones are priced like the Ultrasharp) has internal calibration and are built for heavy, demanding work for years, just like the Dreamcolor. Unlike cheaper monitors or television panels, it will not lose quality. Not to mention they are 10-bit, while the consumer monitors are 8-bit.

For small production houses and content producers like you and me, we don't need anything better than a $2,500 Eizo, if it is paying for itself. If it isn't, we are perfectly okay with an Ultrasharp, or any monitor that does 100% sRGB at more than 350 nits or so.

[Josh Bass]

Thanks. Now with these "good enough" monitors (a $2000 anything monitor, in my case is definitely not paying for itself), how does one calibrate them? A specialist? Spyder (or other similar device0? Via the matrox/aja/whatever i/o box one uses to send the video signal from one's NLE/CC software?

[Sareesh Sudhakaran]

All you need is a good GPU and a calibration kit like the X-rite. Spyder's fine too.

Don't forget middle gray walls! You'll need a hood to cut off light hitting your monitor. Light reduces contrast and kills Dynamic range.

[Chris Soucy]

This throw any light on the Ultrasharps?


CS

PS: That any better?

[Josh Bass]

I thought the idea was NOT to shed light on the Ultrasharp! GET IT? SHED LIGHT?????

But seriously. . .do you have that a little larger? It's very tiny on my screen.

[Chris Soucy]

Upload updated. Got it as a .gif too if that's more usefull.


CS

[Josh Bass]

Thanks. Not sure what all that means, exactly. I'm guessing it's good.