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Thread: 4:2:2 colour sampling format

  1. #1
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    Default 4:2:2 colour sampling format

    Most domestic camcorders work on a 4:2:0 colour sampling format but my camera shoots with a 4:4:2 format. I don't fully understand what the difference is but I think it's basically more grey scale and colour information recoded by the camera. A bit like 16bit and 24bit screen resolutions. I can render with the 4:2:0 format and it looks nice but if I format with the 4:2:2 format I only get sound when I view the video with media player. I presume this is some sort of media player or codec problem.

    My question is 1. will I see a big difference in the image if I try and get media player to work with the 4:2:2 format or 2. is it not worth the hassle or even possible to view without some sort of BBC type of a set up ?

    OR 3. is my question to complex for this forum ?

  2. #2
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    You shouldn't see a great difference. The 4 at the front is the luminance, the second number is the luminance minus (I think) the red and the last number is the blue, if I remember correctly (too lazy to google it) all worked out with maths to get the levels of the colours. So full HD is 4:4:4: although 4:2:2 is generally said to be "broadcast quality" (whatever that non-existent standard really means nowadays) such as BetaSP and 4:2:0, if I recall was DV quality. Since a lot of footage shot on DV was copied onto BetaSP and "sold" as 4:2:2 I suspect that the actual difference is more interesting to those who look at waveform monitors, than those who look at pictures.

    I have a feeling that, in theory 4:2:0 was supposed not to be quite as sharp as 4:2:2 when shooting interlaced, can't remember why.

    I've not been a lot of help have I?

  3. #3
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    You've given me a feel of what I was suspecting. That I probably won't be able to tell the difference. I did a little fun shoot the other day and I thought the colours looks really vibrant without any post work on them and that was rendered in 4:2:0 having seen that it got me thinking if I could get an even better image out of my camera, so that's good enough for me. Cheers Rob.

  4. #4
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    Quote Originally Posted by Midnight Blue View Post
    You've given me a feel of what I was suspecting. That I probably won't be able to tell the difference.
    It is really more important when doing chroma keying. That is when you will notice a difference. 4:2:2 is better.
    Last edited by worddigger; 11-03-2010 at 03:20 PM. Reason: additional thoughts

  5. #5
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    DELETED
    Nothing to do with this thread.
    Last edited by TimStannard; 12-27-2010 at 10:26 PM.

  6. #6
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    lovin' it. Like the ding on the lens too - adds to the feel. Is the skater still alive? When he's not falling off he's excellent.

  7. #7
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    It is really more important when doing chroma keying
    Exactly. This is why doing green/blue screeing via DV is difficult. With 4:2:2 you get more shades of green and blue etc. and that makes it easier for the software to deal with what to take out and leave in since it has more information at its disposal.

    But just looking at 4:2:0, 4:2:2, or 4:4:4 I've never been able to see any difference between them.

  8. #8
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    Just out of interest, this all started with the invention of colour television. Black and white TV sets had become common place, as had transmitting black and white TV.

    To transmit just B&W would be no good for the new colour TV's and to transmit as colour wouldn't be any good for all those people who had spent a fortune on B&W TV's in the days when if you bought something you expected it to last.

    So they devised a system to transmit the luminance and colour separetely. The B&W sets would only display the luminanace and the colour sets would also access the colour information.

    Back then they had similar issues as we recently had when broadcast engineers were looking into how to get the higher bandwidth needs of HD out there. Except they never had the luxury of creating DVB-T2.

    So to reduce the bandwidth, they took advantage of how the eye works. The human eye has two different types of cells, rods and cones, one sees luminance, the others colour. The cells that see luminance are far greater in number, so we have a greater perception in detail to luminance than to colour anway.

    They reduced the resolution of the colour information (Hue & Saturation) and kept the B&W image (Luminance) at full resolution, I've heard from more than one person involved in broadcast engineering at/or around the time that it had the unexpected, but welcomed, side effect of looking more natural to our eyes on those sets.

    All these modern variations on this take advantage of the eye's perception in detail, and reduce bandwidths with no real loss of detail to our eye.

    But the detail does go, as mentioned previously. If you dont capture all the colour information, then that's the best your ever going to have to work with. That's where the jaggy's around the edges of green screen subjects come from, the image looks nice and crisp, but when you take out the green/blue etc. the jaggy's seem to be of a lower resolution than the image.

    The same holds true for colour work (in post), you can go a lot further in adjustment if you have a camera that records all the information. If you do all your colour work in camera this is of course diferent.

    For colour work reasons, I'd record at the higher chroma sampling rate, then reduce this for bandwidth reasons for final output.

    David.

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