Originally Posted by mark haflich
The size of the color space is not limited by HDMI 2.0. Whether, the color space can be reproduced by a display depends solely on the display and certainly no projectors out there can reproduce ITU 2020 because their primaries are not wide enough. Particularly with respect to green and to a lesser extent Red.
Scott. I am not sure of your explanation of what you get with longer color bit lengths, by explanation or analogy was correct, but of course I could be wrong. You say longer bit length, greater saturations can be displayed and then you make an analogy to dynamic range ala audio. My understanding is that the saturations increase as the color space is widened. In ITU 2020 the green primary is much more saturated than the rec. 709 green primary. The Red primary is noticeable more saturated but nowhere the increased saturation of the green. Blue hardly increases in saturation at all. There is no discussion of where the color space of xyYcc (Sony's x.v. color) lies. nor DCI. Todays consumer sets can not do DCI with the exception of the Sony VPL-VW1000/1100ES which has a yellow filter inserted mechanically into the optical engine to increase the if you will the saturations of red and green, red and green combined giving yellow. And DCI produces mainly more saturated yellows than Rec 709 and xyYcc. I am not sure about where DCI fits within 2020. Color bit length has really nothing to do with the color space width or greater area. It has to do with how many individual colors can be shown with the color space and affects visible banding because there will not be a smooth transition between the colors without being able to produce the color between two colors. especially visible in facial tones for example. the wider the color space the more bits one needs to eliminate visible banding.
Your comments please.
And calling Joe Kane a HT geek is just wrong. He is a HT nerd, not a geek.
And Joe is a friend who I like a lot and really is the father of gray scale calibration dating back to horrible gray scale temperatures in early CRT days.
Another thought, color bit length is much more important than chroma subsampling levels and I think 4:2:0 is fine for even 4K 60. But 8 bits which is what we are going to get at 4K 60 sucks and the color space we are going to get, xyYcc is also not going to deliver the promise of 4K.
Finally, the price of the Red Digital Redray is $1750 not $1800. More importantly, it is not presently shipping. Red shipped an initial batch and that has been it. I have had one on order since early Dec 2012 and it has not shipped and most others are in the same boat. Reportedly there are problems with the unit to get it to do simple things like fast forwarding etc. It does seem to work as a 4K playback loop player and I reasonably sure it will play 4K 24 fps out over a single HDMI. If one goes to their store its says if you order one now, it is expected to ship with 2 to 3 weeks. This same expectation has been there for at least 3 months, maybe longer. Like I say orders from early Dec 2012 a few days after the product was announced with a coming soon expectation still have not shipped. Red management is aware that their expectation statement is in serious error but refuse to making it accurate. Until orders are fulfilled with a reasonable pipeline, it should be treated as something that doesn't exist and can't be purchased.
I look forward to your response.
Thanks for your comments. I'm always looking to improve my understanding of things, and if someone can prove me incorrect about something, I welcome it. Also, I don't remember exactly what I said during the entire interview (my brain is a FIFO buffer!), but if I said that color space is limited by HDMI 2.0, that's mostly not true. (Enlarging the color gamut does increase the amount of data to some extent, and if many other parameters are increased as well, an enlarged color gamut could push it over the top of what HDMI 2.0 can handle, but that's a relatively minor point.)
After reading your comments, I've been thinking about color bit depths and the analogy to audio, and I now think the analogy is probably not valid. For audio, bit depth determines the quantization granularity of audio waveforms, whereas with color, it determines the number of steps in brightness between 0 and maximum, which is determined by the display's capabilities. So with color, bit depth does not correlate to dynamic range as it does in digital audio. It seems to me that, for a given bit depth, the increments from 0 to max are finer or coarser depending on the dynamic range of the display; for example, if the peak luminance of a display is 100 nits, the steps in color brightness will be finer than if the display has a peak luminance of 1000 nits. I will study this further.
If I said that bit depth is related to saturation, I was clearly wrong. I know these two things are unrelated. You are correct that saturation increases as the color point gets closer to the spectral locus (the outer horseshoe shape) of the CIE diagram.
As for whether bit depth or subsampling is more important to picture quality, I suppose that's a matter of opinion. I'll ask Joe what he thinks in the podcast today.
Re the price of RedRay, last time I looked, it was $1795, which I rounded up to $1800, but what's $50 between friends? I didn't know it's not currently shipping, nor about the problems you report. Thanks for the update!