Output colorprofiles and compression standards?

[agwah]

Going to the stores and expos of digital cinema stuff one sees that no display or projector behave in the same way. There are tons of varying compression artifacts and colors seem to get destroyed and bent out of shape differently on almost every device.

This effect was the same in photography a couple of years ago, but today most professionals have settled on a couple of standard ways of calibrating their screens and then delivering the image with a widely accepted color profile. This together with that the different printers have had their systems calibrated have made most jobs come out pretty good.

Is there going to be a standard delivery format for most festivals and digital cinema projectors. So that before sending it out, one can utilize the right compression and color profile for a universal and somewhat predictable result across a lot of venues.

Is there going to be a device that can calibrate the home TV/HDTV.

Hoping for a standard developed where one can anticipate the final look on a well calibrated computer monitor.

 

[Chris Kenny]

The DCI standard is supposed to deal with this problem. The spec anticipates that "creative color decisions" will be made on a "calibrated projector in a controlled mastering room", but desktop previewing solutions will no doubt emerge. (Or maybe they exist already? This sort of thing is hard to track down.)

There are already standards for managing color across printers, scanners, monitors, etc. and devices and software that work with these standards. I am unaware of any technical reason these could not be extended to digital cinema projectors. Theoretically, with the right equipment, you could just generate ICC profiles for such projectors, and preview their output in any app that supports ICC profiles, on a monitor that's been calibrated for ICC workflow. Of course, ICC workflow isn't extensively used for video work right now, so it isn't supported by most video apps, but this is something that could change. Anyway, you'd only really need support in your color grading app.

Unfortunately, I wouldn't expect to see color management extend to consumer HTDVs and projectors any time soon. I expect that five years from now, you'll still see something different on every screen when wandering through your local electronics shop. One problem there is that consumer electronics companies don't even really want accurate color. Nice warm oversaturated images look better to the sort of people who buy TVs by wandering around the floor until they find something they like the look of. (That is to say, most people.)

If anyone actually knows if there's a DCI ICC profile somewhere in the world, and how one might go about getting a copy, or if anyone knows what the situation is with creating or viewing DCI masters on the desktop, that would be extremely interesting information. I haven't been able to find anything.

 

[glenn chan]

Rec. 709 defines particular chromaticities (colors) for red, green, and blue. Consumer monitors are supposed to conform to those standards. Color grading should be done on a monitor that follows Rec. 709 colorimetry.

I'm not exactly what the standards say about standard transfer function... I think it's that they assume the transfer function of a CRT. There are multiple viewpoints on what exactly that is though.

1b- Color management in Rec. 709 is simple- grade on a broadcast monitor that follows Rec. 709 chromaticities. Unfortunately, you can't get CRTs like that. And the cheap LCDs (i.e. Sony Luma) aren't close.

SMPTE C chromaticities are pretty close to Rec. 709 though.

2- DCI defines XYZ color space for masters. XYZ is an absolute color space and encompasses every color that we can see. Some/many of those colors exceed the color gamut of real displays; the display system needs to map those colors into ones that can be displayed. This is an imperfect process.

The advantage of this system is that it allows for colors beyond Rec. 709 color space, as long as the display system can display that color. For example, you can reproduce the cyan color used in printing (i.e. if that color were in the scene somewhere).
Downsides may be cost, and inconsistencies in mapping out-of-gamut colors.

I think wide gamut video systems are a pretty recent development, so we may not know that much about their pros and cons in practice. At least personally, I haven't seen that much literature on that.

 

[agwah]

Thanks Chris and Glenn,

DCI System Spec Recommends three formats:
4096 x 2160 JPEG 2000 24 FPS
2048 x 1080 JPEG 2000 24 or 48 FPS
X’Y’Z’
12 bit 16 Ch. Audio

JPG2000
http://www.jpeg.org/public/DCINEMA-v2.pdf
http://www.fnordware.com/j2k/

XYZ Colorspace
http://en.wikipedia.org/wiki/CIE_1931_color_space

From the spec sheet:
http://www.dcimovies.com/DCI_Digital_Cinema_System_Spec_v1.pdf

8.2.2.5. Color Space Conversion
The projection system is required to convert the incoming DCDM* color space to its native color space.

What is this "DCDM* color space" Is it that the JPG2000 has a colorprofile natively or do you select a profile before exporting it to a j2k file?