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Thread: Color space and Log-C workflow with Lightwave?

  1. #1

    Color space and Log-C workflow with Lightwave?

    Im wanting to render to Log-C from Lightwave, specifically in order to make compositing with ARRI Alexa Log-C footage easier and "more correct".

    In the render tab Lightwave offers the ability to render to Cineon color space but I cant see an option to use a LUT in the dropdown. According to this page: https://docs.lightwave3d.com/lw2019/...g/color-spaces Lightwave lets you load your own custom tables or LUTs for rendering?

    There is an option to load/display custom LUTs in the render preview window, so I tried to generate a post production LUT to use with Lightwave from ARRI's LUT generator page: https://www.arri.com/en/learn-help/l.../lut-generator

    Im assuming the correct options for Source Format would be "Scene-Linear Wide Gamut" and the Destination Format would be "Log-C Wide Gamut".... that seems to enable the output options for post production LUTs. But Lightwave needs a .3dl or .cube format and the generator only seems to output 1D LUT output options.

    Has anyone had any experience or luck with this?
    Last edited by scott.newman.ct; 12-11-2019 at 03:21 AM.
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  2. #2
    OK... so if you look in the Preference tab, under CS - I see there is a place to load a LUT as "default final render". Then Im assuming you just choose "default" in the Render tab when setting up your rendering and you get the LUT applied. I havnt been able to test this though as I still cant get hold of a .3dl or .cube version of the ARRI Linear to Log-C LUT.

    Ive written to ARRI about it, hopefully I'll hear something back.
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  3. #3
    Quote Originally Posted by scott.newman.ct View Post
    Im wanting to render to Log-C from Lightwave, specifically in order to make compositing with ARRI Alexa Log-C footage easier and "more correct".

    In the render tab Lightwave offers the ability to render to Cineon color space but I cant see an option to use a LUT in the dropdown. According to this page: https://docs.lightwave3d.com/lw2019/...g/color-spaces Lightwave lets you load your own custom tables or LUTs for rendering?

    There is an option to load/display custom LUTs in the render preview window, so I tried to generate a post production LUT to use with Lightwave from ARRI's LUT generator page: https://www.arri.com/en/learn-help/l.../lut-generator

    Im assuming the correct options for Source Format would be "Scene-Linear Wide Gamut" and the Destination Format would be "Log-C Wide Gamut".... that seems to enable the output options for post production LUTs. But Lightwave needs a .3dl or .cube format and the generator only seems to output 1D LUT output options.

    Has anyone had any experience or luck with this?
    Do you need your final composite to be in Log space? For someone else to color grade the shot later? If not, you could just apply a LUT to your Alexa footage and then composite normally in After Effects.

    If the final composite needs to be in Log space when it is done, for a colorist to grade it later, then I usually render out EXR files from Lightwave, which are Linear. Then in After Effects, drop your EXR footage onto a layer in your comp and add a Effect>Utility>Cineon Converter. Then change its Conversion Type to Linear to Log. This will make it look like your Alexa footage. Then I add an Adjustment Layer on the top layer of the comp with a Lumetri Color effect (this layer is set as a Guide Layer so it won't render). Under the section Basic Correction>Input LUT, I add a ALEXA_defaultLogC2Rec709. This allows your comp colors to look 'normal' again so you can work and do your compositing. And make sure your project is set to 16 bits per pixel.

    When you render this shot out, the LUT adjustment layer won't render or apply itself, and you'lll end up with a Log colorspace shot in the end.

  4. #4
    Thanks Axis3D

    Yes - I need the final composite to be in Log-C.

    What you have suggested is exactly what Ive been doing up until now, but Im finding the cineon conversion doesnt replicate Log-C exactly. Im finding I still have to do color and curve tweaks to the cineon converted image to get it to look correct.

    Another workflow I want to try is using After Effects's color management - where you interpret each of your footage items and then at output/renderingyou can specify the Log-C profile.
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  5. #5
    A friend of mine just sent me this LUT which is supposed to be Linear to ARRI Log-C. I just tried it in LW, its not 100% perfect but it gives a better result than the Cineon profile in my opinion: Lin_to_ArriWGLogC.cube.zip
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  6. #6
    Quote Originally Posted by scott.newman.ct View Post
    A friend of mine just sent me this LUT which is supposed to be Linear to ARRI Log-C. I just tried it in LW, its not 100% perfect but it gives a better result than the Cineon profile in my opinion: Lin_to_ArriWGLogC.cube.zip
    Thanks, Scott

    Thanks for the Linear to ARRI Log-C LUT. Hopefully, it will come in handy for me in the future.

    I'm not sure if you've heard of OpenColorIO, or if you've used it already in your work. It's an open source system for managing color in film pipelines. I tried messing with it about a year ago, but still grappled with wrapping my head around the workflow. Had some success with it.

    http://fnordware.blogspot.com/2012/0...r-effects.html

  7. #7
    Quote Originally Posted by scott.newman.ct View Post
    A friend of mine just sent me this LUT which is supposed to be Linear to ARRI Log-C. I just tried it in LW, its not 100% perfect but it gives a better result than the Cineon profile in my opinion: Lin_to_ArriWGLogC.cube.zip
    Scott, give this one a try, I exported it from Resolve's native Linear to Log C LUT. I don't have any ARRI-C footage on hand to test with, but it looks reasonably flat as you'd expect and loads fine into LW...

    http://files.datausa.com/imageshoppe...om_Resolve.zip

    Regards,

    Jim Arthurs

  8. #8
    Axis3d, yes OpenColor is awesome. Ive been using it to do conversions inside AE using the Nuke default configuration. I still cant get the conversion to be 100% accurate though, but it is pretty close. Good enough to work with for sure.
    Last edited by scott.newman.ct; 12-17-2019 at 11:08 AM.
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  9. #9
    Thanks for the LUT Jim! I'll give it a test ASAP and get back to you and let you know how it goes.
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  10. #10
    Jim, I gave that LUT a test and it seems to give exactly the same results as the one I posted further up this post.

    Whats interesting is that when I do a render out of LW using these Linear to Log-C LUTS and I take the rendered Log result into After Effects and then apply a Log-C to Rec709 LUT the result is quite different to what the LW sRGB or REC709 render looks like.

    Do I have this correct? That Lightwave is outputing Linear information in the "raw" render data, so one would need to use a Linear to Log-C table? I wonder how it would work using an sRGB or REC709 to Log-C table?

    Jim - are you by any chance able to generate a LUT from Resolve that does sRGB or REC709 to Log-C?

    Thanks again for your interest and help with this.
    Last edited by scott.newman.ct; 12-17-2019 at 11:02 AM.
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  11. #11
    OK WAIT A MINUTE!

    Ive got it to work perfectly now - using the Open Color IO plugin inside After Effects with Nuke Default config.

    How interesting that After Effects's own color management and color transforms seem to get it wrong. I was using AE's built in Lumetri Color LUT and then also tried applying the LUT using "Utilities > Apply Color LUT". I also tried re-applying all of this in all the different color management workflows and I couldnt get it to work correctly in any of them!

    @Axis3d, thanks for mentioning Open Color IO, if you hadnt reminded me I probably would have just tried AE's native LUT tools and given up.
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  12. #12
    Quote Originally Posted by scott.newman.ct View Post
    OK WAIT A MINUTE!

    Ive got it to work perfectly now - using the Open Color IO plugin inside After Effects with Nuke Default config.

    How interesting that After Effects's own color management and color transforms seem to get it wrong. I was using AE's built in Lumetri Color LUT and then also tried applying the LUT using "Utilities > Apply Color LUT". I also tried re-applying all of this in all the different color management workflows and I couldnt get it to work correctly in any of them!

    @Axis3d, thanks for mentioning Open Color IO, if you hadnt reminded me I probably would have just tried AE's native LUT tools and given up.
    I forgot about Open Color IO myself. I discovered it about a year or so ago and tried to learn a bit about it, but haven't needed to use it since then. I may pick your brain sometime if I need it on a project

    And yes, you would think that after all these years of development, Adobe would have a more bullet-proof, simple workflow for using footage of different color spaces in After Effects. I guess they figure that most people will use Nuke or something else to do that type of work (which I have in the past).

  13. #13
    Quote Originally Posted by scott.newman.ct View Post
    OK WAIT A MINUTE!

    Ive got it to work perfectly now - using the Open Color IO plugin inside After Effects with Nuke Default config.

    How interesting that After Effects's own color management and color transforms seem to get it wrong. I was using AE's built in Lumetri Color LUT and then also tried applying the LUT using "Utilities > Apply Color LUT". I also tried re-applying all of this in all the different color management workflows and I couldnt get it to work correctly in any of them!....
    Hi Scott,
    can you explain your workflow/settings for this, please?

    ciao
    Thomas
    Web: www.dieleinwandhelden.com

    I use two pieces of the three-piece application with mocap module.

  14. #14
    Sure thing Axis3D - if I can be of help let me know
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

  15. #15
    Hi Thomas, Im assuming you are asking about my work flow inside Lightwave and then using Open Color IO in After Effects?

    Im just going to describe this in simple layman terms seeing as though I myself am pretty simple and a layman... I cant claim to really fully understand what is going on here, but the following seems to work for me:

    So what I am doing is using the LUT that I have posted further up this forum. It is a Look Up Table that converts Linear color profile to the Log-C color profile (well thats how I understand it anyway).


    I want to do this for two main reasons:

    1) I often have to composite my 3D work into live action scenes that have been shot using the Log-C picture profile. So being able to have your 3D renders in that same (or similar) space really helps speed up the amount of fiddling required in the compositing phase.

    2) Even in scenes where the entire composite is with 3D CGI, I enjoy working with Log-C because its an industry standard and when you hand the finished shot off to a colorist for grading, he/she has a standard point to start from when applying LUTs. The other benefit to using Log-C (or Cineon or Linear for that matter) is that it really helps to preserve your detail and information in your highlights and shadows. Details that normally get clipped or lost with an sRGB or rec709 render.

    WORKFLOW IN LIGHTWAVE:

    After hitting the "d" key to bring up the preferences pane, go to the CS tab and where it says "Apply Color Space" use the dropdown for "Default Final Render" and choose "(load table)". You can then browse and add the LUT Ive posted further up this post.

    Then in your Render Properties pane, under the Output tab set your file output Color Space to "(Default Final Render)" and LW will use the LUT that you have specified from the Preferences CS settings.

    Render your frames and then import the sequence into After Effects.


    AFTER EFFECTS Open Color IO WORKFLOW:

    Im working with AE in 16bit mode and Im working with Color Settings > Working Space set to "None" so that Im working with just good old un-managed RGB values (again thats how my brain understands it). I find all the working space options in AE quite confusing.

    Make sure you have downloaded and installed the Open Color IO plugin for After Effects. The plugin appears under Effect > Utilities in After Effects. Once you apply the plugin to your footage item, you will need to load the configuration settings you want Open Color to use. Im using the Nuke Default config which offers nice conversions between different Input and Output color spaces.

    Essentially how I work is I place an Adjustment Layer as the top layer in my AE comp and I apply my Log-C to rec709 LUT to this. All my layers below this are flat looking Log-C layers, but then when you switch on the LUT Adjustment layer on top, you get an idea of what the comp looks like in Rec709 color space.

    So where the discrepancy comes in between After Effects's native transforms vs Open Color's transforms is if I do a comparison between a Rec709 render from Lightwave and a Log-C render out of LW with the LUT applied in AE (gosh I hope that makes sense). The Open Color LUT transform gives me exactly the same result as the reference Rec709 frame out of LW, where the After Effects native LUT transform (applied through Lumteri Color effect) looks quite different and creates some banding.

    I'll see if I can post some examples at a later stage.
    Scott

    Cape Town, South Africa
    http://www.youtube.com/user/independentvfx

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