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11th March 2014, 12:55 | #24801 | Link | |
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Stick with the standard 2.2 power curve for LL Dithering and Smooth Motion, and be done with it. You can always change it if suddenly ITU comes with a new standard (or OLED's get extremely cheap ). One curve cannot fit ALL displays, but all displays can be calibrated to ONE curve (if the display is capable enough).
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System: i7 3770K, GTX660, Win7 64bit, Panasonic ST60, Dell U2410. Last edited by James Freeman; 11th March 2014 at 13:33. |
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11th March 2014, 13:20 | #24802 | Link | |
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It's not what I would prefer,but I assume it's going to be fixed at 1/0.45, which is fine. |
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11th March 2014, 13:20 | #24803 | Link |
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Personally I think I'll vote for BT.1886 hardcoded to a contrast ratio of 1200:1 (best match for sRGB). I don't think the fact that the slope is a little steeper near zero is going to hurt anyone (even monitors with ridiculous contrast ratios) and it should be somewhat better in the reduced bitdepth modes near zero (so for people with 6-bit LCDs, say) while still being continuous (where sRGB is not). IMO these are the configurations we should be focusing on here, since the lower bitdepth modes benefit more from this (at 8-bit the difference from gamma light is miniscule).
But if you end up sticking with 1.0/0.45, I won't complain (like I said I can't tell the difference in 8-bit mode using 8-bit source material, which is all I regularly use).
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Test patterns: Grayscale yuv444p16le perceptually spaced gradient v2.1 (8-bit version), Multicolor yuv444p16le perceptually spaced gradient v2.1 (8-bit version) Last edited by Ver Greeneyes; 11th March 2014 at 13:24. |
11th March 2014, 13:25 | #24804 | Link | |
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I can only speak for myself here, madshi, but I already am very happy with the hardcoded 1/0.45 right now, because the improvements I see at lower bit depths and up easily were worth the time to include that. If there would have been a "simple" fix for the dark areas, I guess that the majority would have never even thought about anything else. Power users always want everything accurate in every case, which is not possible, because sRGB and BT.1886 were never meant for the same tasks. I agree. |
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11th March 2014, 13:51 | #24806 | Link | ||||
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Should work for all algorithms, except "none", of course. |
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11th March 2014, 14:14 | #24808 | Link | |
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I'd rather see 1/0.45 than some arbitrary BT.1886 curve. |
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11th March 2014, 14:53 | #24810 | Link | |
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+1
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http://www.7-zip.org/ Last edited by Audionut; 11th March 2014 at 15:00. |
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11th March 2014, 14:55 | #24811 | Link | |
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Either 1/0.45 or pp2.4. |
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11th March 2014, 15:04 | #24813 | Link | |
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Now the problem is that I don't really know exactly how the different settings are applied. The easiest case seems to be "this display is already calibrated" where you directly get the gamma curve, then it's just a matter of applying this correctly. It gets more complicated when you've got a LUT, I fear that currently those don't exactly have the information you need. What you need is a table that tells you which pixel value has which colour, I fear the LUT does this the other way around. The linear interpolation I proposed also gets quite a lot harder in 3D and depends on whether you use monoColor or oppositeColor noise. I currently know no easy way to solve this. Also if the 3DLUT is created by linear interpolation then it also doesn't make sense to use the shader I proposed (you could technically run the shader using the 3DLUT as gamma curve, but that is probably infeasible.) Anyway I don't think it makes sense to use that shader with a LUT, and I think it will be too hard to apply this LUT correctly (unless you can actually change the way the LUT is created but that's a different matter altogether). So I think that currently the best way to do it is to at least try and apply the "this display is already calibrated" setting 'correctly', otherwise if someone either has no calibration or displays at a low bitdepth then I'd use the shader with some well chosen gamma curve (Bt 1886 sounds reasonable). It might actually be possible to also apply the "calibrate this display by using yCMS" setting 'correctly' since you've got to input a gamma curve, but that will probably require you to change the code for that option entirely, so I don't think that's a good idea. |
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11th March 2014, 15:14 | #24814 | Link | |
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And I thought madVR's Gamma Correction (and 3D LUT Correction) features were supposed to take care of that, not Smooth Motion itself? Anyway, what I was confident about was merely that you should use the same gamma curve to convert to and from LL in SM. And your example gives the exact same result when using a 2.4 Gamma Curve to convert to Linear Light, by the way (that's why I tried blending identical colors: I know what result to expect, while with your example, I'm not sure). EDIT: I think I know why Shiandow and I have different opinions: I am under the impression that madVR mainly works in Gamma Light, and whenever it uses Linear Light, it converts the end result back to Gamma Light for the next step. I believe Shiandow thinks that madVR works in Linear Light and converts to and from Gamma Light whenever necessary (basically the exact opposite of what I think). Last edited by DarkSpace; 11th March 2014 at 15:18. |
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11th March 2014, 15:23 | #24815 | Link |
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Remember though that the constant offset introduced by BT.1886 with a specific contrast ratio doesn't matter for our purposes, since we only care about the (nonlinear) differences between colors. So the only effect of a different contrast ratio is that the slope changes. Since the drawback of using a pure power function is that black gets crushed, I think using a limited contrast is actually safer. It still gets most of the effect of using a nonlinear transfer function without the drawbacks of a pure power law or the discontinuity of sRGB.
That's my reasoning, anyway. I don't think the difference is big enough to make a big deal out of it though.
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Test patterns: Grayscale yuv444p16le perceptually spaced gradient v2.1 (8-bit version), Multicolor yuv444p16le perceptually spaced gradient v2.1 (8-bit version) Last edited by Ver Greeneyes; 11th March 2014 at 15:27. |
11th March 2014, 15:36 | #24816 | Link | |||
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Of course the situation changes if we're talking about doing calibration on the HTPC, or complicated processing (like smooth motion FRC) in linear light, or dithering in linear light. But all of those are strictly optional. Quote:
Last edited by madshi; 11th March 2014 at 15:38. |
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11th March 2014, 16:03 | #24817 | Link | |
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11th March 2014, 16:14 | #24818 | Link | |
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Currently the settings in the "this display is already calibrated" section are only used for 2 things: (1) If the source gamut differs from the display gamut, madVR converts the source gamut. This is necessary because the display doesn't know which gamut madVR is sending. (2) If you enable gamma processing, madVR looks at the desired gamma curve and the display's native gamma curve to calculate a correction which converts the display to the desired gamma curve. But this is only done if you manually activate gamma processing. It's turned off by default. And it should be, IMHO. |
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11th March 2014, 16:56 | #24819 | Link | ||
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11th March 2014, 16:56 | #24820 | Link | |
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And, if we use "disable calibration controls for this display" and don't enable gamma processing, the source gamut is used without correction ?
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direct compute, dithering, error diffusion, madvr, ngu, nnedi3, quality, renderer, scaling, uhd upscaling, upsampling |
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