Logarist - any views?

http://www.logarist.com

This is operating on the outer edge of my colour knowledge, so I'm not clear if the theories hold up. Any views?

Not much new here. He uses one LUT to move images into a standard wide gamut log space, then another LUT optimized for a chosen display standard. It appears that he's created good transforms, but there are two major limitations to be aware of:
1. You need a specific LUT to get from each specific camera and it's specific log or gamma setting. Logarist only provides for a few cameras. If your camera or gamma setting isn't provided you are out of luck.
2. If the image values exceed the range of the LUT, they will be clipped.

If you're working in Resolve anyway, it would be better to use ACES or RCM. Or even a color space transform node in standard RGB mode. All of these will preserve image data rather than clipping with a LUT.

Mixing Light gives a great introduction and explanation of ACES here:

https://mixinglight.com/portfolio/getting-know-aces/

He has most likely done better work than many pro companies- typical

He has most likely done better work than many pro companies- typical

How much work have you seen from pro companies?

I don't mean creative work, but pro as software and hardware manufactures.

Ok I know that in this forum humor is not commonplace! : At first, I thought that one speaks of logarithm neperian or logarithm decimal (Ok hard day)

1. You need a specific LUT to get from each specific camera and it's specific log or gamma setting. Logarist only provides for a few cameras. If your camera or gamma setting isn't provided you are out of luck.

True, but I support a bunch of cameras that Resolve's ACES and color managed workflows don't, and more cameras in total. So your luck is better.

2. If the image values exceed the range of the LUT, they will be clipped.

My LUTs' domains cover the entire range of color values produced by the cameras and used by the display. So nothing is clipped that isn't supposed to be.

I tried it and it is working ok.
I found I could get an identical result with a single node and a few primary adjustments.
I think it's good for NLE software grading but unnecessary for Resolve grading.

True, but I support a bunch of cameras that Resolve's ACES and color managed workflows don't, and more cameras in total.

That is simply not true.

These are the 5 cameras and settings Logarist supports that ACES does not:
Fujifilm F-Log
GoPro Protune
JVC J-Log1
Panasonic GH2 Standard
Panasonic GH4 Cinelike D

Here is the lengthy list of source cameras and settings ACES supports that Logarist does not:
Arri LogC
Blackmagic Design 4.6K Film
Blackmagic Design Film
Blackmagic Design 4K Film
Blackmagic Design 4K Film V3
Blackmagic Design 4.6K Film V3
Blackmagic Design 4K Video V3
Blackmagic Design 4.6K Video V3
Panasonic V35
Sony RAW
Canon C300Mkll CLog Daylight V1.0 Rec.2020
Canon C300Mkll CLog Tungsten V1.0 Rec.2020
Canon C300Mkll CLog Daylight V1.0 Cinema
Canon C300Mkll CLog Tungsten V1.0 Cinema
Canon C300Mkll CLog2 Daylight V1.0 Rec.2020
Canon C300Mkll CLog2 Tungsten V1.0 Rec.2020
Canon C300Mkll CLog2 Daylight V1.0 Cinema
Canon C300Mkll CLog2 Tungsten V1.0 Cinema
REDcolor2/REDgamma3
REDcolor2/REDgamma4
REDcolor2/REDlogFilm
REDcolor3/REDgamma3
REDcolor3/REDgamma4
REDcolor3/REDlogFilm
REDcolor4/REDgamma3
REDcolor4/REDgamma4
REDcolor4/REDlogFilm
DRAGONcolor/REDgamma3
DRAGONcolor/REDgamma4
DRAGONcolor/REDlogFilm
DRAGONcolor2/REDgamma3
DRAGONcolor2/REDgamma4
DRAGONcolor2/REDlogFilm

ACES also supports the following source color spaces:
DCDM
DCDM (Camera)
Rec.2020
Rec.2020 (Camera)
Rec.2020 ST2084(1000 nits)
P3—D60
P3—D60 (Camera)
P3-DCI
P3 DCI (Camera)
P3—D60 ST2084 (1000 nits)
P3—D60 ST2084 (2000 nits)
P3—D60 ST2084 (4000 nits)
P3—D65
P3—D65 ST2084 (1000 nits)
Rec.709 (D60 sim.)
sRGB
sRGB (D60 sim.)

Logarist might be a good solution for certain workflows that use only the cameras it supports and where finishing will be done in an NLE or other app that doesn't support ACES. For those finishing in Resolve, I can't imagine many scenarios where Logarist would be a better option than ACES or RCM.

Jamie LeJeune, I support Panasonic V35, all variants of Canon Log 1/2/3, Canon EOS DSLRs and EOS M cameras with the Neutral picture style, V-Log L on the GH4 (it's not the same as V-Log), and Sony Hypergammas (Cine1 & 2). Raw is supported when you develop to BT.709.

Reasons to use Logarist in Resolve over Resolve's built-in ACES or color managed workflows:

• Support for different cameras & color spaces
• Different rendering: it doesn't force you to use the ACES RRT, and it comes with several different highlight compression curves
• More flexible: you can filter, composite, and color correct in the color space of your choice, instead of being forced to do everything in the ACES or timeline color space

Logarist is aimed at people who deliver standard HD video, not cinema or HDR color spaces. It doesn't do everything that ACES and Resolve's color managed workflows do, but it does things that they don't.

Logarist is aimed at people who deliver standard HD video, not cinema or HDR color spaces. It doesn't do everything that ACES and Resolve's color managed workflows do, but it does things that they don't.

Jacob, can you elaborate on what exactly Logarist can do that I can not do with Resolve?

Hi, Peter. Sure, I can elaborate.

Logarist is a bunch of LUTs that you use inside Resolve with Resolve's built-in color tools. The concept is very similar to ACES or to Resolve's color managed workflow, but there are several differences.

In Resolve, when Color Science is set to DaVinci ACES or ACEScc, all of the output transforms (ODTs) incorporate the ACES RRT. If you like the look of the ACES RRT, then it's fine. But if you don't like that look, you're kind of stuck. I don't like the look of the ACES RRT. It rolls off the highlights too aggressively, which desaturates them and shifts skin tones towards green. Of course it's just a limitation of DaVinci Resolve's ACES implementation, and not a problem fundamental to ACES. If you know how to build your own output transform, this limitation can be overcome.

Logarist's output transforms all use the BT.709 standard, without the ACES RRT. I also have several pre-defined highlight compression curves. But those are really just a convenience for the user. You can roll off the highlights however you want with a Y curve or an RGB curve and achieve something similar.

Logarist does not currently support output in any cinema or HDR color spaces.

One limitation of Resolve's color managed, ACEScc, and DaVinci ACES workflows is that *everything* must be done in the selected timeline color space.

Say you have a clip that needs to be composited with another video. Even if that clip doesn't need color correction, it's still going to be transformed into the timeline color space and then transformed into the output color space. A round trip from Rec.709 to DaVinci ACES or ACEScc and back to Rec.709 is a lossy operation that really shouldn't be necessary, but Resolve doesn't give you any way to bypass that. Try it yourself and check the scopes. The output video won't match the input video. The problem isn't as bad in Resolve's color managed workflow, which seems to have more precise transforms for Rec.709. But in Logarist, it's lossless, because any clip that doesn't need correction doesn't need to be transformed at all.

Or say you want to do your color correction in log (ACEScc) and then apply an effect in the display color space. Resolve's built-in ACES and color managed workflows don't give you any way to do that. Logarist is more flexible in this respect, because every color space transformation is just a LUT, and the LUTs can go into nodes that you place however you want in the node graph. You could, for example, color correct in log, apply an effect in linear, and composite in the display color space.

Resolve's ACES workflow supports a long list of camera color spaces. Resolve's color managed workflow supports a different list of camera color spaces. But you can't use both in the same project. You need to pick one workflow or the other.

Canon Log, for example has these variants supported in Resolve's ACES workflow:

• Canon Log (C100 and C300)
• Canon Log, BT.709 Gamut
• Canon Log, DCI-P3+ Gamut
• Canon Log, BT.2020 Gamut
• Canon Log, Cinema Gamut
• Canon Log 2, BT.2020 Gamut
• Canon Log 2, Cinema Gamut

Resolve's color managed workflow supports these Canon Log variants:

• Canon Log, BT.709 Gamut
• Canon Log, DCI-P3 Gamut
• Canon Log, BT.2020 Gamut

You can see that the color space support is pretty fragmented. If you have a C100 or C300 and you want to use Resolve's color managed workflow, you're out of luck. And neither workflow supports Canon Log 3. Logarist supports all 14 variants of Canon Log 1, 2, & 3 that you can select on the C100, C300, C500, C100mk2, C300mk2, and the C700.

Consider Sony S-Log. Resolve's color managed workflow supports S-Log1, S-Log2, and S-Log3. Resolve's ACES workflow only supports S-Log2. Logarist supports all of the S-Logs, with different gamut choices.

Logarist currently does not support Arri, RED, or BMDFilm color spaces. I figured there wouldn't be much demand for an Arri Log C transform. But if people want it, I can build it. I don't think too many people would have a need for color correction in RED or BMDFilm color spaces, because people usually shoot raw on those cameras. If you shoot raw, you can develop the raw image into one of the color spaces that Logarist supports.

Logarist also has input support for the Neutral picture style of Canon EOS DSLRs and EOS M cameras, Sony HyperGammas (Cine1 & 2), Panasonic GH2, Panasonic GH4 V-Log L and Cinelike D, GoPro Protune, JVC J-Log1, Fujifilm F-Log, Panasonic VariCam V-Log, and BT.709. Altogether that's covering a lot of cameras that Resolve doesn't support natively.

Resolve has input support for a bunch of display color spaces, but I don't know of any cameras that shoot in those color spaces.

If I may interject here... I found this thread by accident.

I am planning to shoot a documentation of an upcoming trip with a Canon 5D3, Canon M3 and a Gopro Hero 3 Black (and a DJI Mavic). I was looking for the ideal file format / workflow to shoot in.
My knowledge of color workflow is somewhat limited. I have been shooting in flat profiles such as VisionTech and Cinestyle, because "its the pro thing to do", but haven't been entirely convinced that it is really so much better (for me). I have a hard time getting the look that I want from a flat profile.

I have only recently "discovered" ACES, which has somewhat improved my control over the image, however I am not sure I am grasping everything there is to the new workflow and the final result (image quality) isn't much better when compared to footage shot without flat profile. (I don't dare asking whether a flat profile with these cameras makes much of a difference, I am surely doing it wrong)

My point is: Logarist, from what I read here, especially considering my camera choices, seems to be the ideal solution? Or would it only complicate things?

Thanks,
Andy

In Resolve, when Color Science is set to DaVinci ACES or ACEScc, all of the output transforms (ODTs) incorporate the ACES RRT.
<snip>
Of course it's just a limitation of DaVinci Resolve's ACES implementation, and not a problem fundamental to ACES.

<snip>
Logarist does not currently support output in any cinema or HDR color spaces.

One limitation of Resolve's color managed, ACEScc, and DaVinci ACES workflows is that *everything* must be done in the selected timeline color space.

Resolve has input support for a bunch of display color spaces, but I don't know of any cameras that shoot in those color spaces.

a few thoughts Jacob;
- yes Resolve's implementation of ACES has far fewer RRT options than Baselight, it's not inhernt to ACES
- i do use Cinema ODT's commonly
- in Resolve/ACES you can use the colorspace transform or DCTL's to move as needed, Baselight has Truelight operator's
- commonly get elements in either 709 (titles, stock footage, archival footage) or ADX (vfx file seq's), use DCDM and DciP3 to check exports... there's a good reason to have those options there

I am planning to shoot a documentation of an upcoming trip with a Canon 5D3, Canon M3 and a Gopro Hero 3 Black (and a DJI Mavic). I was looking for the ideal file format / workflow to shoot in.
...
My point is: Logarist, from what I read here, especially considering my camera choices, seems to be the ideal solution? Or would it only complicate things?

Andy,

Logarist supports the Neutral picture style of the Canon 5D3 and the Canon M3, and GoPro Protune. I don't support any of the DJI log modes, so for DJI footage you'll need to record to a standard display-ready profile and forgo correction, or use the Logarist BT.709 input transform, or use a DJI log LUT. Logarist will let you do any of those, and mix your footage with Logarist-corrected footage from the other cameras.

So, yes, I think Logarist could help for your project. I encourage you to do some tests with each of the cameras, and make sure Logarist gives you the control and look that you want. Ease of use was my goal, and I don't think Logarist complicates the workflow very much considering how it can help you get better looking images. As Dermot pointed out, Logarist doesn't do everything ACES does, but I don't think those things will matter for your particular project.

Let me know if you have questions or need help.

Jacob,

thank you very much. I have made a couple of test shots with the 5D, M3 and gopro and so far I like the look. Would it help if I reduce the contrast of the neutral picture style even further?
I will make some more tests on the weekend with more extreme light situations...

No, you should not alter the contrast of Neutral in the camera. The Logarist input transform is based on a profile of Neutral with contrast and saturation set to zero in the camera. If you want to alter the contrast, do that in the Logarist space after shooting.

As you get into more extreme lighting, you may need to experiment with the exposure setting. Reducing the exposure will extend the highlight range. Increasing the exposure reduces noise. However you decide to set the exposure, you can compensate in the Logarist space. In this respect Logarist is much like shooting raw and then adjusting the exposure slider in Lightroom.

I'm generally not a fan of using LUTS, working hard to learn to grade without.

saw this thread and figured I'd give it a go on a short project (60ish clips) that I shot with a sony a7s in slog2.
gotta say it worked a treat for a quick, simple and clean grade.

just my 2cw

The way I understand it, Logarist isn't really a look but more a modification of the color grading process. The actual grading starts after you set up logarist.

Jacob, regardless of logarist, my impression is that a neutral picture profile doesn't really safe all that much more shadow or highlight detail on a 5D or M3 compared to the standard profile, am I right? I get the feeling that Canon isn't really all that good in this regard. More "professional" logs such as slog2 seem to be doing a better job.

You are right Andy, its not to give a "look". With the Sony slog2 files I was very impressed with how shodows and highlights seem to be protected. Much much smoother gradients in both.

Jeff, glad to hear about your experience with S-Log2 and the a7S. Thanks for sharing. For your next project, I suggest customizing the camera's picture profile with a gamma setting of Cine1 and a color mode setting of Still. I think you'll find on the a7S that Cine1 is much easier to shoot with than S-Log2, and Still delivers more accurate color than S-Gamut.

Andy and Jeff, the "look" of Logarist is standard or neutral. Logarist is based on the BT.709 standard, with some optional customization of my own to improve highlight handling. My goal was always a neutral or true-to-life rendition. If you desire a different look, you can apply it in addition to whatever color correction you do with Logarist.

Andy, yes, the Canon EOS Neutral picture style has roughly the same dynamic range as Standard. It's intended as a display-ready picture style, with slightly lower saturation and contrast than the EOS Standard picture style. Canon Log and S-Log, in contrast, are optimized to capture the usable dynamic range of the camera, requiring further post processing. But Neutral is not bad. By linearizing (and then log-ifying) the color space, you gain some exposure latitude, though not quite as much as on a proper cinema camera recording in raw or in a camera log space. Practically speaking on most cameras, the usability of the shadows are limited by noise more than by the color profile's precision in the shadows. Simply putting a log color space on the camera doesn't magically improve the shadow noise and dynamic range. I profiled the EOS Neutral picture style because it's closer to BT.709 than EOS Stardard is, and I was able to invert its color processing pipeline fairly effectively, if not perfectly. If you are really interested in what the EOS Neutral picture style is capable of, try recording the same scene with a range of exposure settings from several stops underexposed to several stops overexposed, compensate in Logarist, and see how they compare. My guess is you'll have a 1-2 stop range of usable exposure settings. The magnitude of that range is the exposure latitude.

Thanks Jacob.

I've always shot slog 2 with a pro color space. For me it's given the best results, especially with skin tones.

Now that I've given logarist a go I've got some more testing planned this week for Cine styles. Will let you know how I get on.

FWIW - I've found the sony s-gamut for slog2 just too stripped back to be able to get a good grade from it, hence using a (modified) pro color space.

Jacob, thank you very much for your help. It's greatly appreciated. After all, I am a photographer, not a colorist (yet). But it sure is a lot of fun.

I guess there is no harm in shooting my upcoming iceland trip all in neutral picture profile considering the Canon M3 doesn't deliver much more dynamic range anyways. Additionally, I don't want to spend an insane amount of time in post (although, it is usually the edit that takes the longest). For select scenes e.g. aurora I may switch to raw on the 5D3 with Magic Lantern.

Hi Jacob,

Great work. Playing around in the logarist space definitely its advantages. Can you provide any advice on how to handle linear footage? It looks like the only way to place footage in the logarist space is from the Media tab, so there is no way to easily apply for example a BT.709 LUT first? Perhaps you could look into adding linear or sRGB options?

Thanks, Michael.

I'm not really understanding what you're asking. Can you please explain it more? What's the BT.709 LUT that you want to apply? I could support input from a linear color space, but I would need to know the full specifications of that space. sRGB is a display-referred space, so I can't support that without knowing how the camera transformed to sRGB. As an approximation, you can use a BT.709-to-Logarist LUT on sRGB footage. You can read my instructions for that.

Thanks, Michael.

I'm not really understanding what you're asking. Can you please explain it more? What's the BT.709 LUT that you want to apply? I could support input from a linear color space, but I would need to know the full specifications of that space. sRGB is a display-referred space, so I can't support that without knowing how the camera transformed to sRGB. As an approximation, you can use a BT.709-to-Logarist LUT on sRGB footage. You can read my instructions for that.

Hi Jacob, sorry if I wasn't clearer earlier. Yes, I have watched/read your instructions, very helpful and thanks! Let me see if I can be a little clearer.

As you confirmed, there is no Linear-to-Logarist LUT. I can't tell you full specifications of that space, but if it helps, most of the linear footage that I work with is OpenEXR.

The reason I mentioned BT.709 is because I thought that maybe a quick hack for my linear footage would be to apply a Linear-to-BT.709 LUT first followed by the BT.709-to-Logarist LUT—a roundabout way to get into the Logarist space, for sure. However, it seems that one can only transform their footage to the Logarist space from within the Media tab, and one can only apply a single LUT within the Media tab unlike the Color tab? So my question was can one transform to the Logarist space within the Color tab? Alternatively, is there a way to specify two LUTs on the Media tab? Or, are our hands tied, and the only way around this is to build a Linear-to-Logarist LUT? I just wanted to make sure I wasn't missing something.

I realize that sRGB and BT.709 share the same primaries, but the gamma curves are slightly different.

I know that this is a lot to ask of you given how much work you have already put into this. And the fact that you offer this for free is fantastic!

HTH

Thanks for explaining, Michael. I think I understand now.

Your thinking is correct. You would need a linear-to-Logarist LUT, or in lieu of that you could transform from linear to BT.709 first, and then from BT.709 to Logarist. You can do the transformation to Logarist in Resolve's Color workspace. That first transformation needn't be done on the media. You can leave the media's 3D LUT unset, and instead put the camera-to-Logarist LUT on the first corrector node in a series of nodes. (or in your case, a linear-to-BT.709 LUT in the first node, and a BT.709-to-Logarist LUT in the second node)

Be careful that your linear-to-BT.709 LUT does not clip the highlights. Clipping the highlights is a normal thing for a BT.709 LUT to do, but for Logarist, you want to have the full highlight range of the source without any clipping. Assuming the linear space is scene-referred, you can prevent clipping by reducing the gain in the linear space before the linear-to-BT.709 LUT is applied. (then you might need to apply a positive offset in the Logarist space to compensate)

If you can provide the specifications of your linear color space, I can build a linear-to-Logarist LUT for it. I would need to know the chromaticities of the primaries and the white point, the range of color values used in each channel, and the middle grey level. Also it needs to be a scene-referred color space. I can't process a display-referred color space unless the camera-to-display transformation is known.

sRGB and BT.709 aren't just different gamma curves. They're totally different types of things. sRGB is a display-referred color space. sRGB says how a monitor behaves, and says how you would need to encode an image if you want it to be displayed a certain way. BT.709 is a display-rendering and encoding transform for scene-referred images. BT.709 says how to take a camera's image and turn it into something that can be displayed on a standard display and have it look right. BT.709 and sRGB are compatible in the sense that when you use BT.709 to render and encode a camera's image, the result should look correct on an sRGB display.

Jacob,

Thank you for your very elucidating comments.

As for the technical specifications for linear color space, I think that is a question perhaps better answered by some of the other members on this forum. To my knowledge a linear color space is simply a color space stripped of its gamma curve. So what is really needed is a suite of linear-to-Logarist LUTs, e.g. Linear BT.709-to-Logarist. But since you can apply the Logarist LUT from within the Color tab after all, it is probably not needed.