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Video color space
Most DSLRs cameras allow you to specify a color space (sRGB or Adobe RGB usually).
Does this have any effect whatsoever on video files?
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12 Replies
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As far as I know, this only affects photos, since it is a profile mainly for print purposes and was originally developed to achieve better matching between RGB pictures and CMYK prints.
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Not really but, there are different sizes of color space, the Canon 7D has a color space of 4.2.0 I use Cineform Neoscene to transcode my footage to a .avi file and Cineforms codec increases the color space to 4.2.2 This is similar to sRGB and RGB in that RGB is a bigger color space than sRGB.
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Does that mean, you could actually record video in Adobe RGB, Norman?
On my Rebel T2i I can’t even switch between colour spaces when in video mode.
I know, that Adobe RGB contains more information than sRGB (especially in the greens). Assuming you could really record in Adobe RGB, that would be a cool thing, wouldn’t it? And since After Effects can (of course) handle Adobe RGB, having more colour information means more possibilities in post. -
[Norman Pogson] ” Canon 7D has a color space of 4.2.0 “
Color Space and Chroma sub-sampling are not the same thing. The h.264 codec that the 7D uses Y’CbCr color space commonly referred to as digital component and sometimes generically (although technically not correct) as YUV. Y’CbCr is simply a way of conforming image data off of the sensor. sRGB or Adobe RGB for photos are essentially the same thing – a way of conforming image data from the sensor to a space.
In Y’CbCr luma and chroma are separate Y’ is luma and CbCr are the chroma difference channels. Because of this separation chroma subsampling can into play to provide further compression ability.
Because our eyes are much more sensitive to luma (brightness) the Y’ component is hardly ever reduced (a notable exception is HDCAM (not SR) which is 3:1:1) however chroma often is often reduced severely. 4:2:2 means that chroma is being sampled half as often as luma 4:1:1 a quarter as often and 4:2:0 color is sampled 4:2:2/4:0:0 alternating lines
What makes matters a little more confusing is REC 709. For the purposes of color REC 709 describes a gamut. That gamut for REC 709 is significantly smaller then what Y’CbCr is really capable of.
What would be very cool (although bandwidth and other limitations exist) is for these cameras to one day be able to record R’G’B (chroma subsampling doesn’t come into play there) in an MPEG codec similar to how HDCAM SR works.
Robbie Carman
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Colorist and Author
Check out my new Books:
Video Made on a Mac
Apple Pro Training Series DVDSP
From Still To Motion -
Wow, thanks Robbie for that detailed explanation! Greatly appreciated!
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Robbie Carman“sRGB or Adobe RGB for photos are essentially the same thing”
Adobe RGB and sRGB are two different absolute color spaces, they are mapped in a totally different way. They vary widely in “size” of colors they are capable of reproducing, thats why RGB on a computer monitor looks duller than sRGB.
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You misread Robbie’s statement…
He was saying that comparing sRGB and Adobe RGB as Y’CbCr
Not that they do things the same way… but are similar in the way that Oranges, Clementines, and Tangerines are all round Orange Fruit
Richard M. Harrington, PMP
Author: From Still to Motion, Video Made on a Mac, Photoshop for Video, Understanding Adobe Photoshop, Final Cut Studio On the Spot and Motion Graphics with Adobe Creative Suite 5 Studio Techniques
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[Richard Harrington] “You misread Robbie’s statement…”
Thats correct Rich, Norman I was simply trying to make the analogy that placing sensor data into Y’CbCr is essentially the same thing as putting that sensor data into sRGB or Adobe RGB
Robbie Carman
—————-
Colorist and Author
Check out my new Books:
Video Made on a Mac
Apple Pro Training Series DVDSP
From Still To Motion -
It’s quite clear, he put a period and then said “. sRGB or Adobe RGB for photos are essentially the same thing – a way of conforming image data from the sensor to a space.”
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[Norman Pogson] “It’s quite clear, he put a period and then said”
sorry! I never claimed to be a good typer!
Robbie Carman
—————-
Colorist and Author
Check out my new Books:
Video Made on a Mac
Apple Pro Training Series DVDSP
From Still To Motion
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