Cinelog - True logspace conversion for DNG and CinemaDNG footage

[QuickHitRecord]

Andy, thanks for answering my questions.

7) If you are choosing Alexa Log-C Film as the input profile for FilmConvert you should add the Alexa Film Matrix gamut lut on a node before FilmConvert (The Film Matrix will add saturation back to the image and is basically the same as you would do with the Alexa).

Which one is this? I assume it's included in the Cinelog-C package? If so, what is the specific name of the LUT as it appears in the Resolve menu?

[Andy600]

Andy, thanks for answering my questions.

Which one is this? I assume it's included in the Cinelog-C package? If so, what is the specific name of the LUT as it appears in the Resolve menu?

It's called [GAMUT]_Alexa_Film_Matrix.cube and it's in the _Cinelog-C_[GAMUT] folder

[QuickHitRecord]

It's called [GAMUT]_Alexa_Film_Matrix.cube and it's in the _Cinelog-C_[GAMUT] folder

It looks like I only have two files in that folder:

[GAMUT]_Cinelog-C_TYPE1_to_Photometric_REC709_Primaries.cube
[GAMUT]_Cinelog-C_TYPE2_to_Photometric_REC709_Primaries.cube

[dyfid]

Thank you so much Andy, the result is impressive, very realistic colors + the benefits of Cinelog-C

Just one complementary question: what to change in the workflow if I want a sRGB output gamma instead of REC709?

For stills? Perhaps do the gamma tweak in an output node or outside of Resolve? Video would not be output with sRGB gamma.

I have several preset modes on my DELL U2711. I'm using the preset mode called "Custom color" to calibrate the monitor to its native gamut (perfect for photography).

Whilst 'Custom Color' would put your monitor into it's native 'wider' gamut, the bottom line is the purpose of that is to make the monitor more likely, more receptive to achieve 100% 709 coverage in the calibration and profiling process, absolutely no point of the wider gamut if it falls short of any other video or cinema standard, you need to reign it in to 709, produce a monitor / viewer 3D LUT for Resolve from your profiling /LUT creation software.

Resolve doesn't use ICC profiles, if you allow your OS to load an ICC profile at boot or login which will only adjust gamma with a 1D LUT anyway (ICC Color Management within the applications handles the rest) your Resolve session won't be colour managed for your display, if you choose to use a 3D LUT for monitoring in Resolve you really don't want the ICC profile getting in the way adjusting gamma because the monitor 3D LUT may well adjust gamma again and lead to unwanted issues with banding and jacked up black levels.

If you can't prevent the ICC loading at boot or log on, i.e: If you're on a Mac then you would need to feed a monitor directly from a BM UltraStudio Mini Monitor by passing the graphics card output. Even on Windows or Linux a BM Mini Monitor is preferred. At worst if you can't prevent ICC profile affecting output you would need to profile your monitor via a patch generator inside Resolve either by Calman, Lightspace or DispcalGUI, so that the ICC profile gamma mucking around is accounted for in your 3D LUT for monitoring in Resolve.

I also noticed a preset mode called "sRGB". Should I switched to it, create a new ICC profile with my i1 Display Pro and use this combination as my starting point for Resolve (and switching back to the other preset mode/ICC profile for Lightroom)?

Thank you so much for taking the time to answer all our questions!

Monitor presets are worthless unless you are regularly sending the monitor back for recalibration because monitors drift and change over time. Surprised if they're even accurate enough from the factory. Preferably it's best to calibrate the monitor using whatever preset make the display most receptive to achieving 709 and that would probably be 'Custom Color' plus whatever tweaks the monitor will allow with RGB gain and offset, Backlight, Contrast & Brightness. Then profile it with the i1DisplayPro.

But this only gets you close to 709 gamut, part of the goal, also RGB separation or more importantly the minimum of RGB separation along the display curve, screen uniformity in terms of grayscale, native 1080p resolution without scaling and monitor refresh rates (24, 25, 30, 50i & 60i) play a part for video that is. If your monitor only does 60Hz, duplicate frames are added and frames dropping is going to happen for all frames rates other than 30 & 60fps, messing with those smooth pans and motion in general.

Not directly related as you're using Lightroom and photography too for others it's worth considering that it can be a waste of cash to buy expensive 'wild' gamut 60Hz monitors thinking everything is wonderful and calibrated, better to buy a couple of budget monitors for GUI, a BM Mini Monitor and a decent 32"+ LED TV (refresh rates, native resolution) to go with the i1DisplayPro, then at a later date invest in a better 32"+ display depending on finances. The mini monitor is also supported in major NLE's etc so it's no specific to Resolve.

[Andy600]

It looks like I only have two files in that folder:

[GAMUT]_Cinelog-C_TYPE1_to_Photometric_REC709_Primaries.cube
[GAMUT]_Cinelog-C_TYPE2_to_Photometric_REC709_Primaries.cube

It sounds like you're on a Mac? Copying the updated luts may have deleted the other folder contents. Just copy the original pack back to the Resolve LUT folder. You may need to re-copy the updated luts manually.

[Andy600]

@dyfid - you make some very valid points. A lut box is worth the investment if your monitor cannot load luts.

I should point out that the Cinelog-C monitor luts are simply a Cinelog-C to Rec709 or sRGB gamma transfer function with primaries transform from wide gamut to sRGB colorspace. You need to calibrate your monitor for accurate color reproduction and always use scopes to double check levels/saturation etc. If you use the monitor lut slot (in the Resolve Lut panel) for an actual monitor profile lut you can use the Cinelog-C monitor lut on a node (i.e. a track node which affects everything), and just remove/disable it before rendering.

[dyfid]

@dyfid - you make some very valid points. A lut box is worth the investment if your monitor cannot load luts.

Only if bypassing the OS level ICC profiles and colour management via something like a Mini Monitor or preventing the ICC loading in the first place if using the graphics card output otherwise the LUT box will probably not be getting a 'clean' signal.

LUT Boxes are £300, rather invest that in the 32"+ screen, use a BM Mini Monitor and monitor LUT in Resolve to a dedicated 32" and use the GUI monitors for apps like Lightroom where sRGB would be the target. Can see the benefit in LUT Box if jumping between display targets.

[swinxx]

hello andy,
i am really interested in your luts and own a canon 5d mk3, i have began to read through this thread but it is really long and it seems that things slightly change with more experience and time and new tools.. i am interested in the up to date workflow and would really like to  read your manual before i buy the stuff.. is it available anywhere?

and andy, can we have a sneak look to the new homepage..? should be finished soon, no?

thx

[QuickHitRecord]

If you are choosing Alexa Log-C Film as the input profile for FilmConvert you should add the Alexa Film Matrix gamut lut on a node before FilmConvert (The Film Matrix will add saturation back to the image and is basically the same as you would do with the Alexa).

Using the Alexa Film Matrix before FilmConvert is giving me a very yellowish cast. I'm finding that it looks much better without it.

So far, the best-looking results I have found are from BMD Film (4K) > Cinelog-C > Alexa Log-C to Rec.709 LUT > FilmConvert.

[QuickHitRecord]

What would be the best way to make a Color Match (color chart) adjustment in Resolve 11 if I'm using BMD Film 4K Color Space / 3D LUT Input: BMD Film to Cinelog-C / Output Alex Log-C to Rec. 709? And while I am asking, are the Input/Output LUTS "overriding" the nodes, or do the nodes take effect in between LUT applications?

[QuickHitRecord]

In the weeks that I spent contemplating whether or not to buy Cinelog, I kept hoping that someone would post a side-by-side comparison with VisionColor's free VisionLog. Now that I have purchased it, here is that comparison.

No adjustments have been made, except for using an X-Rite Color Checker with the Color Match tool in the first node, and a project-wide gamma boost of 1 (footage was a little underexposed to start with). Each LUT was applied in a subsequent node:

Rec709




BMDFilm 4K (no highlight recovery) > BMDFilm to VisionColor LUT




BMDFilm 4K (no highlight recovery) > BMDFilm 4K to Cinelog-C




BMDFilm 4K (no highlight recovery) > BMDFilm to VisionColor LUT > VisionColor LUT to Rec709




BMDFilm 4K (no highlight recovery) > BMDFilm 4K to Cinelog-C > Alexa Log-C to Rec709

[Andy600]

What would be the best way to make a Color Match (color chart) adjustment in Resolve 11 if I'm using BMD Film 4K Color Space / 3D LUT Input: BMD Film to Cinelog-C / Output Alex Log-C to Rec. 709? And while I am asking, are the Input/Output LUTS "overriding" the nodes, or do the nodes take effect in between LUT applications?

Hi QuickHitRecord,

Is this the Alexa log-C to Rec709 lut that comes with Resolve?

The Alexa Log-C to Rec709 lut will work in so far as a gamma transfer (and it looks like a nice fit) but it is for a different colorspace and has some tonemapping specific to Alexa wide gamut RGB. This results in a colorshift and over saturation if you use it with Cinelog-C (a different colorspace) and it is why the neutrals chips have a tint and color saturation extends well below luminance values (this should be quite noticeable on the Resolve Vectorscope).

If you like the gamma curve you can apply a 1D version of the Alexa lut (gamma only) and either add your own saturation and/or Colorboost or one of the gamut luts in the Cinelog-C pack, in this instance the Rec709 or sRGB gamut lut. Incidentally, Colorboost is just Resolve's name for 'Vibrance'.

As you might not know how to convert the Alexa lut to a 1D lut I have done it for you and uploaded it here: http://we.tl/yMkFskLsgD

Regarding your Colormatch question. You should be able to find the answer a few posts back. Basically, Add 3 nodes in Resolve, apply the Cinelog-C input lut (type2) on node 1 and the Cinelog Rec709 1D Output lut on node 2, then use Colormatch to target Rec709 gamma and colorspace on node 3. You can then remove the Rec709 output lut node (2) and add another node after the Colormatch node and add this new Alexa 1D lut to that note: Your grading is best done before the Alexa Rec709 lut as it clamps output levels.

Regarding Rec709 curves. This might give you more of an insight into the differences between various luts (signal traces of the gamma transfers in 1D):

Alexa Log-C to Rec709 (as comes with DaVinci Resolve)



Cinelog-C to REC709 1D output lut (not including log transform)



Cinelog-C to REC709 1D output lut (including Cinelog-C log transform) - This is the gamma response Resolve expects to see as Rec709 source gamma in Colormatch




BMD Film to VisionLOG-RAW (not including Visionlog transform)



BMD Film to VisionLOG-RAW to Visionlog REC709 Neutral (including Visionlog log transform)



VisionLog to REC709 (not including Visionlog Log transform)

[morsafr]

Hi Andy thanks for your explanations.

I tried the Alexa Log-C to Rec709 LUT and I like the results (first graph). Indeed the highlights are much less clipped and the shadows are more opened than when I use the simple Cinelog-C to REC709 output LUT (second graph).

I'm wondering how to achieve the third graph. Which LUT should I use to achieve "Cinelog-C log transform"?

Sorry for all these questions but these LUTs are quite new to me!

Thanks again.

[Andy600]

Hi Andy thanks for your explanations.

I tried the Alexa Log-C to Rec709 LUT and I like the results (first graph). Indeed the highlights are much less clipped and the shadows are more opened than when I use the simple Cinelog-C to REC709 output LUT (second graph).

I'm wondering how to achieve the third graph. Which LUT should I use to achieve "Cinelog-C log transform"?

Sorry for all these questions but these LUTs are quite new to me!

Thanks again.

You're welcome

The 1D version of the Alexa lut works well with Cinelog-C (as it should).

The 3rd graph is what you get when you combine the BMD Film 4k to Cinelog-C Input lut + Cinelog-C to Rec709 1D output lut. It's the same as Cineon log but remember you are only looking at the 1D gamma trace here and there is a big 3D color component in the input lut that is not shown in the graph (the 3D part is basically the Cinelog-C colorspace). When I get some time I will render some 3D pointcloud diagrams of the colorspace.

[QuickHitRecord]

Is this the Alexa log-C to Rec709 lut that comes with Resolve?

Yes, this is the Alexa Log-C that comes with Resolve 11.

...and the Cinelog Rec709 1D Output lut on node 2

Sorry, but do you mean [OUTPUT 1D] Cinelog-C to Rec.709 1.95 Gamma? I am getting weird results with the workflow that you had suggested above (major blue cast when I delete the second node).

[Andy600]

Yes, the [OUTPUT 1D] Cinelog-C to Rec.709 1.95 Gamma lut. It sounds like you may be altering the target color temperature? If so, leave it (and the whitepoint value) at the default settings i.e. only change the source and target gamma/colorspace to Rec709.

Edit: Also, white balance your image as best you can before using Colormatch.

[QuickHitRecord]

Here are the three nodes with the LUTS that you had specified (this is with a project setting of BMD Film 4K color space). You can see my target settings in the first grab:



And then here's what happens when I disable [OUTPUT 1D] Cinelog-C to Rec.709 1.95 Gamma in the second node:



Adding the Alexa Log-C 1D LUT after this just makes the blue look deeper.

What am I missing?

[Andy600]

Ok, this is where Colormatch isn't very useful but you can try this:

Select the Cineon to Linear Lut (found in Resolve's VFX folder) then choose linear as the source and target gamma (rec709 colorspace) on the colormatch node. Then remove the Cineon to linear node and add the Alexa 1D lut after the colormatch lut.

Colormatch is by no means perfect and this is pretty typical of the issues people are seeing. It's not Cinelog related because it happens even with Resolve's built in luts.

BTW, what are your white balance settings and was this shot under florescent or LED lighting? These light sources can cause big problems for Colormatch.

You could also try using the Alexa lut for Colormatch instead of the output lut but you might get some non-linear gamma shift that clips the output. This is also a problem with colormatching in Cineon logspace.

If you are getting good results with the Rec709 output lut in-place, why not leave it and grade under it? (i.e. on new nodes before the Rec709 output lut)

Also, you have to make sure that the chart is evenly and well lit, without any shadows or obstructions (i.e. no fingers over the black patch).

The middle grey patch (bottom row, third square from the right) should be exposed so it sits at about 410 - 420 on the waveform monitor. There is a good explanation of this here:

http://www.dvinfo.net/article/post/resolve-10-waveform-values-for-the-unsure.html

[morsafr]

You're welcome

The 1D version of the Alexa lut works well with Cinelog-C (as it should).

The 3rd graph is what you get when you combine the BMD Film 4k to Cinelog-C Input lut + Cinelog-C to Rec709 1D output lut. It's the same as Cineon log but remember you are only looking at the 1D gamma trace here and there is a big 3D color component in the input lut that is not shown in the graph (the 3D part is basically the Cinelog-C colorspace). When I get some time I will render some 3D pointcloud diagrams of the colorspace.

In this case I don't understand what the first graph represents.

What I'm seeing is that "[OUTPUT_1D]_Cinelog-C_to_REC709_1.95_Gamma.cube" is producing a much contrasty look compared to "Arri Alexa LogC to Rec709 1D.cube". Is it logical according to your graphs?

Maybe I don't interpret the graphs right!

[Andy600]

In this case I don't understand what the first graph represents.

What I'm seeing is that "[OUTPUT_1D]_Cinelog-C_to_REC709_1.95_Gamma.cube" is producing a much contrasty look compared to "Arri Alexa LogC to Rec709 1D.cube". Is it logical according to your graphs?

Maybe I don't interpret the graphs right!

Ok, the 1D output luts basically transform Cineon log gamma (which is the gamma curve of Cinelog-C) to whatever the target gamma of your output device is (i.e. Rec709, sRGB, BT1886 etc). These luts are not intended to be applied as a 'look' because, as you say, they can appear too contrasty, especially with high dynamic range images and they only alter the gamma of the image. In normal colorgrading you would grade under the lut (i.e. the rec709 output lut is on the last node - though this is not a rule). You would add a node before the output lut and add your own curves, lift/gamma/gain adjustments to adjust the shadows, mids and highlights to your own taste, plus any color adjustments you want to do.

The output luts basically emulate the gamma of an output device such as a computer monitor (sRGB) or HDTV (Rec709). Most colorists tend to use BT1886 as it is less contrasty by default meaning you pull down the shadows towards black rather than push them up. If you do these corrections before the lut you will be working with the full data range. The output lut clamps the output bounds to a 0.0 - 1.0 data range. If you are doing broadcast work you can also switch on the legalizer in Resolve 11 to make sure your final output stays within legal broadcast levels (saturation and luminance).

The luts that come with Cinelog-C are really a toolkit for working with raw/log footage but we are making some nice Powergrades (advanced 'look's) for the new website that will show you how to make the best of the luts. They will also help you understand the purpose of each lut and how and when to use them. Powergrades are much more than a one-click 'look' lut and we will show you why this is too.

[morsafr]

Thanks a lot Andy!

Looking forward for your next updates (powergrades...)

[QuickHitRecord]

@Andy600 I am following your suggestions closely and still getting weird color casts resulting in unusable footage (color chart was evenly lit with a single bounced tungsten source; I did color match when the chart was not obscured at all). I am not sure where the disconnect is.

Based on your suggestions, I've tried a few different applications of the Cinelog-C LUT. These are some of the better ones, but they are still shots in the dark (make sure to move the cursor from the video pane so that the playhead disappears and you can read my notes):

Of course, I'll be exporting before the final node with the finishing LUT is applied. I've left them enabled for reference.

I am just trying to find a good, latitude-friendly starting point to which I can export. Let me know if you think I'm close with any of these.

EDIT: I always assumed that the color checker was automatically performing a white balance. Perhaps that is where the disconnect has been. I changed my project settings to reflect a proper white balance from the get-go, and then color matched again. I have replaced the original file with the new one.

[Andy600]

@QuickHitRecord

Hi,

The first thing I noticed is that your white balance is incorrect in the first shot (original Rec709) because the neutral patches have a greenish colorcast (I'm judging by eye on a laptop but I'll check on the scopes later). Colormatch always works best when you have neutral white balance to start with as Resolve doesn't need to do so much color shift. Try isolating the white chip using a power window and offset the tint until it centers on the vectorscope then adjust the color temp until it looks how you want it to (warm, cool etc).

So, in the order of the tests (I'll call them V1, V2 etc)

V1 - see above
V2 - colorcast is still evident even after colormatching - see above
V3 - better. No color cast but skin tones are getting a bit magenta
V4 - about the same as V3 but gamma difference is causing desaturation
V5 - bad color - incorrect use of Colormatch (should only be Colormatched after the input lut)
V6 - Slight colorcast - correct the WB and try again

I will send you a 1D only input lut to try (by PM). This will not introduce any color shifts so it will work better with Colormatch but will affect how our other luts look.

Although Colormatch can be used with Cinelog-C it (Cinelog-C) it really only needs footage to be white balanced because the color component (3D part) has some very specific color shifts that enhance color separation and skin tones. Colormatch will simply negate these changes (or try to). It's a bit like trying to Colormatch using a PFE. It will destroy the characteristics that make the PFE unique. If you simply want color chart matching, the 1D Input lut I'm sending will produce the most neutral result but it's not Cinelog-C.

To use: set Resolve to BMD Film 4k and add > new BMD Film 4k to Cineon 1D input lut > 1D Rec709 output lut > Colormatch. You can then substitute the output lut for the Alexa 1D lut if you wish.

[morsafr]

Hi Andy,

Could you also send me this new LUT?

I'd like to experiment with it as Colormatch is important in some of my videos (nature).

Thanks!

[bennyray1]

"More detailed information will be in the full updated user guide."
Hello Andy, has the new user guide been released yet? I have been following this post and trying to pick out some of the useful tips you have been giving to the users of the new Cinelog-C but I think I would benefit more if I had a the user guide. Just wondering,thank you sir again for all your hard work and customer service sir.