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Discussion Starter · #1 ·
Does anyone have a color space primer? When using a video processor, you have control of the the color space (RGB, YCbCr, etc.), but it is confusing on what is the best color space to output from each device (if you have the ability) and what color space send to the video display from the VP.


I'm assuming the best color space setting maybe specific to a particular manufacture so how do you find out what the optimum color space to use?
 

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Quote:
Originally Posted by snooktarpon /forum/post/17050766


Does anyone have a color space primer? When using a video processor, you have control of the the color space (RGB, YCbCr, etc.), but it is confusing on what is the best color space to output from each device (if you have the ability) and what color space send to the video display from the VP.


I'm assuming the best color space setting maybe specific to a particular manufacture so how do you find out what the optimum color space to use?


The best colour space is not a fubction of the manufacturer...the image is ultimately converted to RGB thus the question is which combination results in i) the least amount of conversion between colour spaces ii) the best de-interlacing and scaling iii) the best colour accuracy and iv) conversion to RGB...with so many combinations and permutations it is generally a matter of trial and error to see which looks best...
 

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Quote:
Originally Posted by snooktarpon /forum/post/17058881


Are there standard test patterns (on DVE DVD, etc.) that are good for testing the different color spaces?

The test pattern work regardless of whether they are SD or HD...the issue is the colour space twist; that is, a SD test disk inserted a blu-ray player will have to be properly setup depending on whether you want to calibrate to SMPTC-E or REC709...


The preferred approach that I like / use is to use SD test patterns when calibrating to SMPTC-E and HD test patterns when calibrating to REC 709 as this avoids any and all colour space twisting issues...


HTH
 

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Quote:
Originally Posted by snooktarpon /forum/post/17050766


Does anyone have a color space primer? When using a video processor, you have control of the the color space (RGB, YCbCr, etc.), but it is confusing on what is the best color space to output from each device (if you have the ability) and what color space send to the video display from the VP.


I'm assuming the best color space setting maybe specific to a particular manufacture so how do you find out what the optimum color space to use?


If you want a university level text about color space there is a good book by Charles Poynton. Won't exactly tell you how to set up your scaler but will give you all the background behind it.


Here's some free stuff from him: http://www.poynton.com/ColorFAQ.html
 

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Discussion Starter · #6 ·
What I was asking about test pattern is what should you look for to determine if a particular color space is better (RGB vs YCbCr)?


I have a feeling the differences will be minimal and may not be noticeable using the naked eye, a blue filter, and a color test pattern. If that is the case, then I don't see how color space choice is that critical. When using a VP, you have color spaces options so I thought maybe there is a methodology to selecting a particular color space.
 

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There's no particular advantage to either. If you had an xvYCC source (which you almost certainly don't), you'd want to use YCbCr, but otherwise, it's they're basically equivalent.


I would personally tend to try to minimise the number of conversions. Conversions can lead to rounding errors.


So as a first pass, for a computer display, output RGB, because the computer works in RGB. For a DVD/Blu-ray, output YCbCr, because the data on the disc is in YCbCr.


The display has to ultimately use RGB for output, but it may well convert incoming RGB to YCbCr to (pointlessly) allow the Colour control to work on it, before going back to RGB.



So you could find yourself going YCbCr on disc -> RGB on HDMI -> YCbCr in TV's adjustments -> RGB display! Outputting YCbCr over HDMI avoids that sort of daftness.


If your TV's colour control doesn't work on RGB input, that's a good sign, and suggests the TV handles RGB better. In which case the choice of outputting RGB or YCbCr from the player boils down to whether you trust the TV or player to do a better conversion. The conversion is well-defined, and they should give identical answers, but TVs do tend to have deliberate errors in their conversion matrixes to counteract other deliberate errors in white balance. In a well-calibrated system, the players YCC->RGB conversion may be better.


There may be other factors, like there may be a full-range/limited-range ****-up at one end of the link rendering levels bad on RGB, and using YCbCr would side-step that problem.


Also, YCbCr 4:2:2 permits greater bit-depth, which may be an advantage if you're performing any sort of gamma/brightness manipulation in the player. It would avoid posterisation. HDMI 1.3 adds Deep Colour for YCbCr 4:4:4 or RGB 4:4:4 as well, but YCbCr 4:2:2 has the advantage for pre-HDMI 1.3 kit. Don't use YCbCr 4:2:2 for computers though - you lose horizontal colour resolution, whereas DVD and Blu-ray have lower colour resolution to start with, so don't lose anything by using 4:2:2.
 

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...When using a video processor, you have control of the the color space (RGB, YCbCr, etc).....


RGB and YCbCr are not color space. They are video signal formats. They both produce the same color. Color space relates to the signal ratios required to generate specific colors.
 
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