Thread: A better way to grade Ursa Mini CinemaDNGs

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  1. #21  
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    Quote Originally Posted by dermot shane View Post
    i have emails from major facilities stating RCM, Truelight & ACES are not to be used on the film i'm hired to grade, only display refered workflow, only useing flatened EXR /DPX/ProRez, no access to the raw /cam orig...
    you may not be aware of what we are asked to take on, but that only means you are not aware of what's going on in the background of a post house, lack of awareness is to be expected, post houses do not share this stuff with cleints generaly
    I can only speak to my own experience.

    I know enough to ask the questions. I wouldn't accept a workflow I wasn't happy with.

    And if I went to a session where a process was happening that I didn't want or wasn't specified, I wouldn't proceed without asking why it was being done in a non specified way. Are you saying then one can't see a slight of hand ?



    Quote Originally Posted by dermot shane View Post


    i know more than a few colorists, don't know of anyone like that tho....

    I do.




    Quote Originally Posted by dermot shane View Post

    i have zero clue what youre on about here, can you be even a tiny bit more specfic?
    In this post, 4 above your own....

    Quote Originally Posted by CaptainHook View Post

    Quote Originally Posted by Juan Melara View Post
    Are you sure its 6000k and not D65? As pretty much every colourspace standard is D65 unless it specifically says so.
    I'm speaking of the white point of the source illuminant, not the colour space. Using Arri again as reference, take a look at the IDT folder for exposure index 800 and notice how many files there are:

    https://github.com/ampas/aces-dev/tr...alexa/v3/EI800
    Did you just learn something ?

    Quote Originally Posted by dermot shane View Post

    no matter what you think of the post sup, and how highly you rate your skills in post, we have to respect the post sup's call's, just as we respect the DP, the Director, the Producer's, the QC houses, and the bond agency...
    Sure.

    And we can do that through education. I've had no trouble bringing post sups, colourists, networks and studios along for the ride. So far I'm doing pretty well and I haven't screwed it all up. Guess I'm just lucky hey ?

    It's usually pretty easy to demonstrate these kinds of issues. I just hate that I have start again every time.


    Quote Originally Posted by dermot shane View Post
    overall i thibk you and Mr Hook may be over rateing yourselves in terms f knoledge of post where the rubber meets the road, but then you have said you are not a colorist, so you get a partial pass, opnions with out a solid foundation and based on a lack of knoledge are only that... opnions

    Yeah. I guess.

    It's what creative people have. Opinions. Thanks for the pass.

    JB
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  2. #22  
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    one should not assume that the colorist is the one making the decisions on the color path.... choice of CDL/LUT? sure - choice of tool set? maybe, sometimes - choice of color path? not really, that's in colabaration with the stake holders, no one works in a vacum, if the DP has enough pull get the Post Sup, Producer's and Bond to agree with a prefered workflow, awesome, bring it on...

    ps, 99.9% of the work i do in my suite is ACES, has been for years - first film i graded in ACES was in the summer of 2014 in Nocoda FimMaster, long before Resolve offered the choice, and working in AP0 was challengeing but the clean maths were worth the work, i get a choice, my friends working in facilities do not, this i know...

    ihe d60 thing? an assumption bundled into an IDT is not a color path, it's one part, (and not really a large part either) of a complete entity, once in linear light the working white point is defined by the ODT.. some camera's IDT assumeing 500 degree warmer whiteppint is not much of a deal once in the system esp with stuff like Baselight's color temp tools at hand ;-)
    Last edited by dermot shane; 11-25-2017 at 02:22 AM.
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  3. #23  
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    Quote Originally Posted by CaptainHook View Post
    I'm not in the Resolve team so my perspective is from the camera side and storing the data - where our SDI outputs are 10bit 422, and ProRes 422HQ (10bit) for recording is overwhelmingly the most commonly used format by people shooting our cameras (from conversations we've had with customers and even seeing recent facebook group polls etc). So for our cameras this is the reality we work with.
    That makes complete sense. Consider me on board with maximising the use of all the bits, even when using 10bits. I've done some further testing and even though It's not noticeable on the majority of footage, it is when working with synthetic tests like gradient ramps. And I'm sure there are plenty of potential worse case type scenarios where it could be a life saver.

    So as you commented on Jason Bowdach's FB post, with relation to curves, "better" is subjective. So take a look at the image below comparing two curves. One of them is a pretty standard log curve (not LogC), the other is BMD 4.6k Film. Both curves occupy the full range of values, maximising the use of all the bits.

    Subjectively speaking, which would you prefer as a start point, which would you prefer to grade?



    Objectively speaking, I can tell you one of them won't require you to pull out information from the shadows, the same one won't require you to shape the highlights. One of them is fully Cineon compatible when scaled back to the typical Cineon range simply by using the contrast tool. The same technique on the other one will make it even harder to pick out the values in the shadows.

    I keep using this same test shot as I think its one of those worse case scenario type shots I mention above. Not in the sense that its a bad shot (it's actually pretty awesome) but more in the sense that its pushing the camera to the limit of what dynamic it can handle and store. And it's showing up some potential difficulties that other shots may not show.

    You mention the high end needs adapt to how other cameras respond. I don't think you need to worry about them, they have the resources and the know how to figure all this out. You don't need to worry about people like me as we are more than capable of figuring it out too.

    You need to worry about the 30-40 or so people that uploaded grade tests of this same material, and couldn't wrangle the shadows and highlights. You need to worry about everyone that downloaded and worked with this test footage and couldn't tell there was an issue with the saturation. You need to worry about the people that are still not getting it right in some of the Ursa Mini productions I watched on youtube whilst researching this tutorial.

    So who are these people? Well they're your customers.

    In my humble opinion, keep the way you fill up all the values. That puts you ahead of everyone not doing that, including Arri. But possibly revisit the way the curve handles the outer most values, particularly in the shadows. The Ursa Mini is a fantastic camera, but I think it could be even better!

    Juan
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  4. #24  
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    I might be wrong but you just mapped wider LOG curve suited to wider dynamic range sensor data to the lower dynamic range sensor data. As result you got shadow recovery effect. Each sensor have native hardware-based response curve and input LOG curve must match that response. That is the reason why every camera manufacturer design its own LOG curve that match better to sensor low level data processing methods they used and to the actual sensor dynamic range. If you shoot same scene with actual Alexa camera and put same LOG curve and same LOG to REC transform node to the footage it will not have so washed shadows as sample from UM4.6 camera. Same concept goes to different color Gamuts.
    P.S. I never use ARRI cameras but my conclusion just based on open sources ARRI footage i downloaded and tested here and there.
    P.P.S. As i earlier it is just user option. Different LOG curves (and Gamuts) just works in different way and have different contrast response and contrast center Pivot point. But you can get same final result.

    Final LOG to Rec conversion LUT or transform method with proper dynamic range compression and highlights rolloff is way more important part in the grading chain.
    Last edited by shijan; 11-25-2017 at 07:26 AM.
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  5. #25  
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    Quote Originally Posted by dermot shane View Post
    one should not assume that the colorist is the one making the decisions on the color path....
    I know.

    But they do get to choose how they approach the grade within the defined tool set. And I constantly see idiotic things like starting with the Arri REC709 LUT as a starting point on a grade with Ursa originated material. That's just wrong and I've seen it go wrong and even when I ask for the colourist not to do it, they tell me that they get better results with Blackmagic shots. Until of course you get a shot that doesn't. You literally have to demonstrate it before they'll believe you, and they resist auditioning "your" way, because of exactly the same attitude I sense from you. I'm, just the dumb client who knows nothing and you as the colourist are all over it. You find out it was a different model of Blackmagic camera that their remembered history was with. As I mentioned in another thread, it takes till about episode 3 for the colourist to really understand how to get the most from the Ursa shots I shoot. I've seen it happen with many colourists.

    This kind of misunderstanding happens all the time to me with name and unknown colourists at big places and small places, not just with Blackmagic cameras but with other as well. Usually I let them do their process, because hey, this is acreative process and I don't want to mess with anyone's "way" of getting to the end result, as long as the result we're all happy with.

    And then when we can't get a result I expect or get image problems, then we get to wind their process back and we interrogate it and lo we find we can get the better result after all.

    I have the greatest respect for colourists. I can't do what good colourists do. They collaborate and multiply and take my work far beyond what I can ever do by myself.

    I just want to understand how they do it and when it doesn't work out, to be able to look at why. Look at the very fact that this thread exists, that someone has to teach and preach a better way to grade.




    Quote Originally Posted by dermot shane View Post
    ihe d60 thing? an assumption bundled into an IDT is not a color path, it's one part, (and not really a large part either) of a complete entity, once in linear light the working white point is defined by the ODT.. some camera's IDT assumeing 500 degree warmer whiteppint is not much of a deal once in the system esp with stuff like Baselight's color temp tools at hand ;-)

    Again, I think you're illustrating my point about knowledge. You missed it.

    I'm not talking about what you can correct with baselight. We're talking about an assumption about the CST tool within Resolve and the assumption it makes about the camera's whitepoint. Not Baselight.

    We're talking about the accuracy of a transform (the CST tool) when it assumes the camera's whitepoint is always 6000K. Other values are extrapolated from the 6000K reference.

    And it could be a lot different to a shot that I did last week where I was at 2600K. That's a substantial difference, not just "500" degrees.

    Did you know that 6000K was the assumption ? I didn't.

    JB
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  6. #26  
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    i knew that, i graded the first promo for Arri touting the Alexa - i had these transforms before they were released, and had to go through them to understand what i was dealing with, but i had developer to ask at the time.

    i've only done one series shot on the 4.6, using Resolve in ACEScct, the camera looks really awesome when exposed properly, great skintones from the get go

    with the show on 4.6 as always i prefer to keep the color path as clean and simple as possiable, the camera responds well, easy to work with - generaly i use exposure/contrast/pivot/saturation, and avoid lift/gamma/gain maths are cleaner, less pulling and pushing the image

    Resolve also has color temp adjustments (and L*a*b color science if one can make it work, i can and do), a 500degree shift to warmer is pretty minor really.

    and ACES is platform agnostic, same maths present to Luster, Nucoda, Baselight..Resolve, sane maths when working with the image, same maths on output
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    Anyone know where you can still find this footage for download? I'm pretty sure I downloaded it a long time ago, but I seem to have misplaced it. I have a theory that I want to test out.

    EDIT: Nevermind, was finally able to find links to them. Sorry for the bump!
    Last edited by RyLo; 01-02-2018 at 02:38 PM.
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    I'm trying out this method and having problems with areas of extreme contrast. I'm not sure if I'm doing something wrong or it's just a quality of outputting to Rec.709. I see a LOT of harsh, ugly fringing around things like lights/headlights from vehicles at night.

    This seems to happen the *moment* I put it into Linear gamma in the Camera Raw tab.

    I haven't really noticed it except in these instances. Otherwise, I haven't really had any trouble with it. A little puzzled.

    Using the method here, with no grade applied (literally just set up the color transform > node > transform structure, just did nothing on the second node). Check the headlights.
    Using BMDFilm (no grade/nodes applied--headlights look great)
    And BMDFilm with very basic primaries, just to see
    I could be doing something completely wrong, but I've looked over the settings from the video a dozen times. I know what I'm seeing in Juan's video, but highlight rolloff is nonexistent for me. Footage was shot in Raw on UM4.6k at 800 ISO.
    Last edited by TravisA; 04-01-2018 at 09:05 PM.
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  9. #29  
    Quote Originally Posted by TravisA View Post
    I'm trying out this method and having problems with areas of extreme contrast. I'm not sure if I'm doing something wrong or it's just a quality of outputting to Rec.709. I see a LOT of harsh, ugly fringing around things like lights/headlights from vehicles at night.

    This seems to happen the *moment* I put it into Linear gamma in the Camera Raw tab.

    I haven't really noticed it except in these instances. Otherwise, I haven't really had any trouble with it. A little puzzled.

    Using the method here, with no grade applied (literally just set up the color transform > node > transform structure, just did nothing on the second node). Check the headlights.

    Using BMDFilm (no grade/nodes applied--headlights look great)

    And BMDFilm with very basic primaries, just to see

    I could be doing something completely wrong, but I've looked over the settings from the video a dozen times. I know what I'm seeing in Juan's video, but highlight rolloff is nonexistent for me. Footage was shot in Raw on UM4.6k at 800 ISO.

    Same here. But easy fix, just desaturate blues.
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  10. #30  
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    Quote Originally Posted by deezid View Post
    Same here. But easy fix, just desaturate blues.
    Thanks, I'll give this a shot. I would really not want to have to go through and regrade everything for this project. Since it looked fine/great for most shots, I didn't notice this until I was literally at the end.
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