Thread: X-rite color checker for ursa mini pro

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  1. #31  
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    Quote Originally Posted by shijan View Post
    ColorChecker is ColorChecker it can only match different cameras to look similar. But i experimented with Arri color tool and with the luts generated in that application. It is only my own current conclusion and i may be wrong, but seems that Arri looks are not suited well for non Arri footage. It seems that Arri looks itself have some kind of additional background matrix color correction that puts in place colors from Arri cameras (Actually this is what Blackmagic should do for their cameras instead burn in that correction to camera ProRes files)
    I find that when you set timeline to Arri WideGamut/LogC and apply Arri looks to Blackmagic footage it looks more less ok. But when you apply same Arri look to Blackmagic footage that was corrected with ColorChecker - reds are shifted into deep dark magenta and some other colors became very strange and overloaded.
    Is that something they could do in a firmware update? As I find grading the blackmagic footage pretty hard(I am not a pro colorist). Canon, red and alexa are way more easy to grade then blackmagic. They should put a team on this, and really start cracking the color science of those camera's and implementing that in the UMP.
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  2. #32  
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    Quote Originally Posted by shijan View Post
    ColorChecker is ColorChecker it can only match different cameras to look similar. But i experimented with Arri color tool and with the luts generated in that application. It is only my own current conclusion and i may be wrong, but seems that Arri looks are not suited well for non Arri footage. It seems that Arri looks itself have some kind of additional background matrix color correction that puts in place colors from Arri cameras (Actually this is what Blackmagic should do for their cameras instead burn in that correction to camera ProRes files)
    I find that when you set timeline to Arri WideGamut/LogC and apply Arri looks to Blackmagic footage it looks more less ok. But when you apply same Arri look to Blackmagic footage that was corrected with ColorChecker - reds are shifted into deep dark magenta and some other colors became very strange and overloaded.
    What format is your original video in? Is it ARRI raw or is it Prores in log C?
    Here are before and after samples of wide DR wide gamut CDNG raw exposed ETTR from an earlier version of Resolve without color management. graded from scratch with raw menu tools in REC709. REC709 is seriously chroma clipped before correction.



    Only peak values that were clipped in the raw file still show as clipped after grading.



    With a true raw format one can work from wide gamut full linear DR to a finished grade without loss, or one can convert to a log space and work from the compressed values out.
    If one wants to use third party LUTS as part of a grade, then your timeline needs to be in the color space the LUT was written for.
    What I love about Resolve's color managed options is that you have a mathematically correct conversion between color spaces to match your chosen workflow, whatever that might be.
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  3. #33  
    Senior Member shijan's Avatar
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    I use BMMCC RAW files for all my tests. Mathematically correct is not always good looking. There are a lot of different ways to work in Resolve with RAW and get more less same result. I tested different workflows and ended up to work in LOG timeline and use RAW sliders only for White Balance and Expose. When you work in LOG timeline you are see all actual data. You don't have any hidden highlights which needs to be recovered with hidden sliders or curves. Digital tools in LOG behaves same as light and colors in real world and you start to think in real f-stops instead of abstract slider positions and guessed curve shapes. And finally it is simpler, faster and more precise and natural looking. LOG curve was created for film scans long time ago because people wanted to work with scanned digital data same as they work with physical film. In LOG All parts of tonal curve interact in very complicated way. RAW sliders are just digital amplification of sensor signal, they just change parts of tonal curve in very simple way.
    Last edited by shijan; 06-26-2017 at 10:56 PM.
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  4. #34  
    Senior Member CaptainHook's Avatar
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    Quote Originally Posted by shijan View Post
    It seems that Arri looks itself have some kind of additional background matrix color correction that puts in place colors from Arri cameras (Actually this is what Blackmagic should do for their cameras instead burn in that correction to camera ProRes files)
    Arri's LogC does have a Wide Gamut matrix applied the same as BMDFilm with Gen 3 colour science to take it out of camera RGB. Going into Rec709 requires another matrix again for both Arri and BM "log footage" including a gamma function. So we are the same in that respect, the actual matrices are obviously different.


    Quote Originally Posted by shijan View Post
    I find that when you set timeline to Arri WideGamut/LogC and apply Arri looks to Blackmagic footage it looks more less ok. But when you apply same Arri look to Blackmagic footage that was corrected with ColorChecker - reds are shifted into deep dark magenta and some other colors became very strange and overloaded.
    That's because Arri's LogC to 709 LUTs are expecting Arri Wide Gamut as the input - when you run Blackmagic footage via the ColourChecker plugin you cannot target Arri Wide Gamut as a destination colour space. If you run Arri footage through the same process you will find odd results too. If you want to run Blackmagic footage through Arri's LUTs, you could use Resolves FX plugin (or RCM) to transform into Arri Wide Gamut and Arri LogC and then it would look more reasonable when applying the Arri LUT - but from my testing with both cameras it wont make them match but can be "okay" under daylight type sources. It doesn't really work well under tungsten in my testing. However, i find just using BMDFilm with a tone curve applied and overall sat adjustment is a better match visually across colour temps than trying to transform into Arri Log C and applying their 709 transform. YMMV.
    Blackmagic Design
    My BMD LUTs.

    **Any post by me prior to Aug 2014 was before i started working for Blackmagic**
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  5. #35  
    Senior Member shijan's Avatar
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    I found that there are two different implementations of RAW input colors in Resolve. To get correct colors from RAW you need to bypass input color space transform in project settings:




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