Thread: Desaturated shadows?

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  1. #71  
    Moderator Phil Holland's Avatar
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    ACES, current version, has known high/near edge of gamut issues.

    When creating your own gamut limiter and LUT a few questions will need to be asked and the one shoe fits all situation gets trickier.

    However, that shoe works best when the footage itself is not over exposed, which is a problem everybody deals with it appears.

    Again, RWG/Log3G10 is not out of gamut, you are trying to put a really wide gamut color space into a smaller one and in this case clipped values.

    Graeme it appears has gone super accurate with what the current IPP2 transforms do, which is good because well exposed high gamut colors render well.

    It's not uncommon to develop 2 or even 3 LUTs to have some sort of gamut limiting logic to them to handle clipping differently. Since you're working in Resolve you are presented several different ways through OFX plugins. You can also develop your own limiter within nodes.

    Fundamentally you are clipping values and the camera is still attempting to capture something, which is creating colors it can possibly capture. When creating your limiter you might encounter situations where you could possibly record an non-clipped value, but your limiter may trample on it. Which is why it's a bit tricky to do a one shoe fits all situation, which gets you back to not overexposing.

    It's interesting to see how each manufacturer handles clipped values. It's a problem everybody deals with. Some just choose not to deal with it which creates the worse offensive results and occasionally wild artifacts.

    What's even more interesting is seeing out of gamut colors that make it to the big screen that haven't been attended to after a full color and finishing pipeline has been explored. Don't know how that stuff passes QC, but it happens alarmingly often.
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  2. #72  
    Senior Member Christoffer Glans's Avatar
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    Quote Originally Posted by Phil Holland View Post
    ACES, current version, has known high/near edge of gamut issues.
    Seems like we have to wait for a release again. Whenever I'm like "Ok, let's change workflow to ACES" I always encounter problems. When it's ready I think it's the best route to take, but it never seems to be optimal and ready for prime use.


    Quote Originally Posted by Phil Holland View Post
    However, that shoe works best when the footage itself is not over exposed, which is a problem everybody deals with it appears.
    Can still happen though, I mean, this shot of the tail-light is me just screwing around filming some test shots, but the environment is pretty well exposed while light sources will always be extreme. If I were to expose for the light sources I can end up with underexposed subjects instead.

    Quote Originally Posted by Phil Holland View Post
    Graeme it appears has gone super accurate with what the current IPP2 transforms do, which is good because well exposed high gamut colors render well.
    Sure, but how? I'm trying to limit the out of gamut stuff manually, but I'm not really getting it right, not like the limiter does. So how did he limit the gamut for each color space when developing the LUTs?

    Quote Originally Posted by Phil Holland View Post
    It's not uncommon to develop 2 or even 3 LUTs to have some sort of gamut limiting logic to them to handle clipping differently. Since you're working in Resolve you are presented several different ways through OFX plugins. You can also develop your own limiter within nodes.
    This is just it, trying to limit with nodes instead of the gamut limiter, but I'm not sure how that's done?

    I found that instead of limiting the gamut to REC709, which as you say creates some weird color shifts in colors that are not out of gamut, I tried to limit to DragonColor 2 instead, which gives a much better result "out of the box". Have to start the grill to see how it reacts to fire.

    REC709 limited




    DragonColor2 limited

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  3. #73  
    A couple of thoughts re: Resolve, here. I avoid using LUTS. As you know, LUTS will clip at the limits of the gamut, since the "correction" is applied in discrete values. Using a color space transform FX is a completely mathematical transform in 32 bit space, therefore with no limits. Second comment relates to the default application of IDT and ODT saturation and luma rolloff or knee in the Resolve color management workflow. Default Resolve v17, especially with wide gamut workflows, will place a knee on the gamma in an attempt to roll off the highs and shadows in a smooth fashion. I, routinely, shut the s-curve, saturation and luminance remapping off in Resolve Settings/Color management, because I don't like the way it rolls off the shadows and highlites. All this is clearly defined by Alexis Von Hurkman in his Ripple Training description of Resolve 17.
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  4. #74  
    Senior Member Christoffer Glans's Avatar
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    Quote Originally Posted by Bill Ravens View Post
    A couple of thoughts re: Resolve, here. I avoid using LUTS. As you know, LUTS will clip at the limits of the gamut, since the "correction" is applied in discrete values. Using a color space transform FX is a completely mathematical transform in 32 bit space, therefore with no limits. Second comment relates to the default application of IDT and ODT saturation and luma rolloff or knee in the Resolve color management workflow. Default Resolve v17, especially with wide gamut workflows, will place a knee on the gamma in an attempt to roll off the highs and shadows in a smooth fashion. I, routinely, shut the s-curve, saturation and luminance remapping off in Resolve Settings/Color management, because I don't like the way it rolls off the shadows and highlites. All this is clearly defined by Alexis Von Hurkman in his Ripple Training description of Resolve 17.
    Since the thread has been going on for a while, which part are you referring to? Red transform LUTs can be used either as node LUTs or within Raw settings and the behavior of desaturated shadows appears the same in both workflows. You mean to say that shutting off these settings will fix the problem with the Red transforms? I'm not seeing the same when creating my own LUT (intended as output LUT with grade applied before it in RWG/LOG3G10 space)

    Not sure which settings you mean? S-Curve is only for contrast adjustments, the lift gamma gain ignores that setting.
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  5. #75  
    I'm not saying, definitively, that turning these setting off will fix what you're seeing. I'm just suggesting that it might be worth checking. You're right about the s-curve. The tone mapping settings leave me feeling uncertain about using them in any workflow. Again, I don't use LUTS because the matrix quits working at the limits of the matrix. Resolve Color Space Transforms are a much more mathematically accurate than LUTS.
    Then there's this...https://www.youtube.com/watch?v=drCub1gplV4
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  6. #76  
    Senior Member Christoffer Glans's Avatar
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    Quote Originally Posted by Bill Ravens View Post
    I'm not saying, definitively, that turning these setting off will fix what you're seeing. I'm just suggesting that it might be worth checking. You're right about the s-curve. The tone mapping settings leave me feeling uncertain about using them in any workflow. Again, I don't use LUTS because the matrix quits working at the limits of the matrix. Resolve Color Space Transforms are a much more mathematically accurate than LUTS.
    Then there's this...https://www.youtube.com/watch?v=drCub1gplV4
    How do you mean more accurate? Within a dedicated 709 timeline it does transform correctly, but the color cast, especially greens, goes through the roof. So I'm wondering in what way we're talking "accurate" here? If used as an output LUT, any grade before it will work within LOG3G10 and Resolve is 32 bit in its core, so there shouldn't be any clippings before the transform.


    Color Space Transform



    IPP2 Medium/Soft



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  7. #77  
    Senior Member Christoffer Glans's Avatar
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    Quote Originally Posted by Bill Ravens View Post
    The explanation under the video doesn't make sense. Komodo shoots RAW, there's no "in-camera tone mapping" that is in any way hardcoded. And if shooting in ProRes that is a lossy 422 codec so it should never be used in LOG with grade added in post. 422 HQ is so lossy that LOG is already compressed and applying any grade will destruct it even further. That noise is more visible after tone mapping is totally natural since added contrast will make everything pop, noise included.

    If shooting with R3Ds, it's RAW so you can go from a scratch RWG/LOG3G10 and grade without any LUT tone maps. That's what I've done for my own general LUT.

    I'm not sure what this video is supposed to show because the workflow seems totally uninformed about how Red IPP2 works while the look of the final video doesn't really look good at all. Extreme green cast with highlights being pink.
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  8. #78  
    As best I can describe it here's what I can offer....
    Most commercially available LUTS are generated within the range of IRE values appropriate for REC709. Once you go outside of IRE 16-235, these LUTS will clip information. LUTS are discreet mathematical values contained in a matrix of values. Once you exceed the matrix endpoints, the transform collapses. Not knowing how you generated your own LUTS, I do know that Ben Turley's LUTCALC will give you the option to create a LUT at full range IRE0-254. Using Resolve's Color Space Transform (CST), you avoid the limitations of exceeding the gamut and colorspace because the entire FX uses math to calculate the transform in 32 bit space. The transform is perfornmed on a mathematical algorithm that is continuous in mathematical space, unlimited by IRE values, or the inaccuracies of interpolating matrix values. Any out of range values are retained and not clipped at the limits. The Resolve CST also gives you the option of how to apply, or not, tone mapping.
    Last edited by Bill Ravens; 03-08-2021 at 04:33 AM.
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  9. #79  
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    Quote Originally Posted by Christoffer Glans View Post
    The explanation under the video doesn't make sense. Komodo shoots RAW, there's no "in-camera tone mapping" that is in any way hardcoded.
    Unless Redcode is 12logarithmic. Then there is some sort of tone mapping going on. however, I doubt that is the culprit, as other 12bit files seem fine, and like you have mentioned before, it shows up in the monitors and evf. But in the very strict sense, if redcode is recording in a 12bit log file, then there wold be a tone mapping going on. but again, I am not saying this is the issue.
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  10. #80  
    Senior Member Christoffer Glans's Avatar
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    Quote Originally Posted by James Sielaff View Post
    Unless Redcode is 12logarithmic. Then there is some sort of tone mapping going on. however, I doubt that is the culprit, as other 12bit files seem fine, and like you have mentioned before, it shows up in the monitors and evf. But in the very strict sense, if redcode is recording in a 12bit log file, then there wold be a tone mapping going on. but again, I am not saying this is the issue.
    But I'm talking about problems with their tone map transforms that are integrated into the camera, you can shut them off and use whatever you like, just as I've done with my LUT. The file is RAW, 16bit, their tone mapping is just metadata decode. You can even start with linear if you like. There's a difference between hardcoded tone mapping, like if you shoot ProRes with IPP2 High/VerySoft, but if you shoot R3D you can change it however you like. At the moment I'm working on a LUT that has nothing of the problems I initially pointed out. But I'd like Red to adress the behavior of their IPP2 tone mapping LUTs because as it is now I can't really use them for a fast turnaround but instead develop my own transform for it. Only hurdle I have now is to get this new LUT transform to the level of quality as Red's in terms of reliability and consistency, while making sure I get rid of out of gamut problems and such.

    So I'm not really sure what you are talking about when you use terms like LOG and tone mapping in the way you do. It's RAW, so it doesn't really matter as long as the sensor doesn't screw things up.
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