Color Spaces in Video

A

Andeeeh

New member
Hi all,

I have trouble understanding color spaces in the video world,

What I (think) I know so far is that each coder has a different color space or gamut?
or rather they each compress the color gamut differently. Codecs such as Prores 422, and 444 have the the widest color space, only 422 loses a bit of information the blue chroma and red chroma.

I am working on a project and i am baffled on the color shifts i am seeing when i am outputting to different codecs etc and even watching the same file across different players.

I know I can assign a color profile to a composition in after effects and embed that profile in some codecs? Can i do that in premiere?

If anyone has any information, can correct me or explain to me about color spaces in the video world and how i can control it or keep all my output the same.
 
Color profiles =/= color subsampling.

Without getting into it too much, you can have color profiles in certain formats based on their ability to manage color. Think of color profiles as defining "what color this video is supposed to be", while color subsampling is much closer to the resolution of color. Wikipedia has a very good description of the process.

http://en.wikipedia.org/wiki/Chroma_subsampling

While a loss of resolution is definitely noticeable, 4:2:0 is so common DVD and Blu-ray delivery simply because the effect is supposed to be minimal in the human visual system. I suspect you are seeing a bigger change in color profiles between codecs, rather than subsampling (unless you're working with green screen footage, then you have to seriously consider color subsampling).

As for your real question of wanting to maintain consistent colors, it really depends on your source material, how the camera records, etc. Most prosumer HD cameras record in Rec.709 colors (regardless of how you alter the color, cinema gamma, etc), and many professional codecs offer options for how to encode color profiles.
 
Thanks for that explanation! so can you explain to me color profiles and how each codec handles them generally? and how I can assign color profiles?

The project i am working on right now involved me shooting on a 5D MKII which is records into a H.264 MOV ( REC.709). I converted all the files into Prores 422 (HQ) via mpeg stream and edit them in premiere. I then encode them to different deliverables such as MOV H.264, H.264 MP4, FLV files.

So does this mean all my outputs still retain a REC.709 gamut? or are them compressed down because i am outputing to codecs of lesser quality and lose some color information?
 
H.264 is generally Rec.709, and anything out of the Canon DSLRs is certainly 709, though you already know this. ProRes is also 709 (though I rarely use it, so I don't know if there's a configuration for that, but it's default seems to be 709), so the problem stems from Premiere, at least I suspect so. Given that it likely shares its importing engine with After Effects, the following article may help you:

http://blogs.adobe.com/toddkopriva/2009/03/prores-422-colors-in-after-eff.html

Basically, as far as AE is concerned, it attempts to open ProRes in straight sRGB, which is of course incorrect, and it wouldn't surprise me if Premiere treated ProRes the same way. Again, generally, H.264 is Rec.709, and I have no idea for FLVs (I assume VP6?), so you should be fine for your output.
 
It is good learning about the color spaces in video.It is really some great features discussed here about the adobe color scheme and nice blog shared too.Thanks for whole information.
 
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