Neutral LUT creation

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  • #7569

    Simjedi
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    First off I would like to thank your for this awesome program!  🙂

    I’m currently using DC in a entirely different manner than what it was created for. I’m using it to create test patterns for .dds textures via PhotoShops “Contact Sheet II” function to import into a game. I am then using 3d LUT Creator with it’s “Chart Grid Tool” to match up the imported .dds test pattern texture displayed in the game engine to the original test pattern on my hard drive. So far I have achieved good results.

    First I would like to say that I am using no calibrated profiles and am only working with the ones included with this program PhotoShop and Arg-II.

    So I have a few questions that maybe someone could answer.

    I want to create a neutral lut to then apply 3d LUT Creator’s tone mapping results on top of it and was wondering what would be the best settings to create one?

    So far I have been using the same source-to-target profiles (mainly sRGB/Linear) and the “Absolute Colorimetric” option to create [email protected] .png luts. But have noticed a few inconsistencies with the “Tone Curve” settings. If  “Unmodified” is selected then shouldn’t it output as the standard 2.4 gamma? Because if the 2.4 gamma is chosen it gives a completely different result. It is also different from 2.2 or the many others in between. So what gamma is this option outputting?

    I have also been experimenting with other color profiles. And while my current monitor cannot display the wider gamuts over sRGB, doing conversions has given some surprising results. Some games have true HDR so would there be any benefit in creating a neutral HDR lut without conversions? I don’t know if ENBseries can accurately display them, but it does accept them. This option would be for those that do have HDR monitors.

    Thanks in advance.

    • This topic was modified 3 years, 1 month ago by Simjedi.
    #7581

    Florian Höch
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    I want to create a neutral lut to then apply 3d LUT Creator’s tone mapping results on top of it and was wondering what would be the best settings to create one?

    A “neutral” LUT would be one that passes values through unchanged, so it’s a bit unclear why anyone would need this (it’s the same as using no LUT at all)? Or do you just want a PNG image with linearly increasing RGB values for applying your own modifications later on?

    But have noticed a few inconsistencies with the “Tone Curve” settings. If “Unmodified” is selected then shouldn’t it output as the standard 2.4 gamma?

    No, “unmodified” means use the source profile TRC and do not override (TRC settings will have no effect).

    #7583

    Simjedi
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    Yes I was wanting a neutral lut for applying effects on top of it. DC as far as I can find produces the highest quality .png images that’s accepted by either ReShade or ENBSeries. Of course I’m a noob at these things and if there is a better option I’m unaware….lol

    I’m using them for shared game presets and the largest .png images so far have been 4096×64 8bit sRGB but these larger ones with higher bitdepth would a nice asset to have, especially in the ProPhoto color space.

    Thanks for replying since I’m using the program far out of scope for which it was intended.

    #7584

    Florian Höch
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    if there is a better option I’m unaware

    These linear PNG images are trivially easy to create programmatically. See attached.

    I’m using them for shared game presets and the largest .png images so far have been 4096×64 8bit sRGB but these larger ones with higher bitdepth would a nice asset to have, especially in the ProPhoto color space.

    There’s no colorspace involved. Linear stays linear no matter the space.

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    #7592

    Simjedi
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    Nice thanks for that.

    Could you possibly point me the direction so that I may create my own then? I’m not a programmer so it has to be as simple a possible…lol

    #7634

    Florian Höch
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    Could you possibly point me the direction so that I may create my own then? I’m not a programmer so it has to be as simple a possible…lol

    That would be difficult, I can’t think of a straightforward way doing it e.g. in a GUI driven app.

    #8068

    Mindflyer
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    That would be difficult, I can’t think of a straightforward way doing it e.g. in a GUI driven app.

    It’s actually really simple, they’re just linear gradients in R, G, B. Photoshop for instance lets you view the RGB channels separately, so you can see that the following LUT swatches decompose into these RGB channels:

    So you can see that you can trivially create swatches of any size and arrangement by just tiling black and white gradients and merging them as RGB channels in Photoshop.

    #8079

    Florian Höch
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    So you can see that you can trivially create swatches of any size and arrangement by just tiling black and white gradients and merging them as RGB channels in Photoshop.

    Careful: Photoshop gradients are not using linear increments of RGB, so they are not suitable for creating a “do nothing” LUT where input = output.

    #8096

    Mindflyer
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    They should be as long as you select a document working space with a gamma of 1.0. I think by default, gradients are dithered though, so that may mess with things.

    #8106

    Florian Höch
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    They should be as long as you select a document working space with a gamma of 1.0.

    The document color space doesn’t seem to influence the gradients at all.

    #8108

    Mindflyer
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    The document color space doesn’t seem to influence the gradients at all.

    I should’ve known better than to assume Adobe would do anything correctly instead of having ugly hacks in place that don’t respect ICC profiles.

    #25659

    fedelin
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    Hello Florian,

    I have read this ineresting post and basically, I am wondering if what is done by Jacob Swing in this video

    would be possible with DC instead of https://generator.iwltbap.com/ that doesn’work on linux ?
    If so, would you attached a screenshot of the parameters then I can better understand?

    Best regards,
    François

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