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Dealing with compression artifacts and yucky image quality in LOG color space?

Discussion in 'Pro/Adv Discussion' started by Justin Kietzman, May 14, 2016.

  1. Justin Kietzman

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    I've been working with the Phantom 3 Advanced and I never seem to be able to get the LOG footage to look any good, I keep trying to shoot in it because it is similar to the Blackmagic footage I work with on a daily basis.

    The LOG color space seems to really bump up the compression of the image, it can be seen very very heavily at exactly 45 seconds into this video we made a while ago:



    (just jump ahead, video is boring), if you look at the trees in the middle of the river, it should be painfully obvious.

    I am currently working on another piece for a client, that has a lot of trees in the shot, and unfortunately I shot in LOG colorspace back when I took the footage months ago.

    Does anyone have any idea how to combat this, other than pumping the contrast slider to 100 and hoping that helps?
     
  2. MikeyOnline

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    LUTs are the way to handle D-Log space. What software do you use: can it handle application of 3D LUTs? If so, you can try these two that I made:

    Feedback on this 3D LUT

    See my notes in that thread though: I've not had much luck getting any one LUT to match all shooting conditions. That is, I've found you need a different LUT for different lighting and exposures. Seems like D-Log space doesn't follow the same tone curves for various exposures which makes it hard to dial in. As a result, I've stopped using it and have just gone back to "None" for color.

    You may also want to check out these LUTs. I have not tried them but $25 may be worth it for you:

    PRESETS FOR DJI LOG

    Oh yeah, forgot to mention. I believe the reason the compression artifacts show more in D-Log is that by the time you apply the proper contrast, whether through a LUT or other means, you've compressed the dynamic range a bit making the artifacts show more by the time you make your adjustments. With the other color presets, the color is adjusted pre-compression which helps.

    Best of luck,
    Mike
     
  3. shockwave199

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    What frame rate are you filming in? With the P3A, it's common knowledge that if it's 60fps, there is a bug that drops the bit rate substantially. You first need to drop the camera into photo mode and then back to video mode and then film. That will give you full bit rate while filming. I do this regardless of what frame rate I shoot in, even though it's only reported to happen in 60fps. This may not be causing your problem but it's worth a try. For some odd reason I can't play your video. I've never had any luck correcting compression artifacts after the fact. The only thing I do is very high renders so as not to make matters worse. Anyway, good luck.
     
  4. 2nd2non

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    I hear the current FW version 1.8 has issues with D-log. I've stayed on 1.6 for this reason. This has been reported on this and the inspire forum
     
  5. froezen

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    One school of thought is that shooting in log on these cameras will never give great results with 8 bit colour. This informative video explains why;
     
    #5 froezen, May 15, 2016
    Last edited: May 15, 2016
  6. MikeyOnline

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    I happen to agree with that video. Same thing I've found: I gave up on D-Log for the same reasons (and more).

    Mike