FS7: LUTCalc v2.0 - Now with Mac App Store and Google Chrome Web Store versions

Hi Alohype,

could you do a 'save settings' (yes, its there now!) and PM the file to me? Also, what post software are you using to apply the LUTs?

Thanks,

Ben
 
Hi All,

I have updated LUTCalc to v2.1 on GitHub, the Chrome Web Store and the online version. The Mac App version is still pending approval by the Mac Store but as this seems to be taking a little longer than I thought (probably the arrival of the new iPhone and iPads) I wanted to mention it now because there is an annoying bug in v2.0. Basically, the output levels were not always being set to 'legal' when they should have for some of the LUT format presets.

Sony MLUTs were behaving correctly, which is the main reason I didn't spot it immediately. If you are using the OSX version, until the v2.1 update comes through on the Mac Store, just keep an eye out that the output range is 'legal' or 'data' as appropriate for your application. There is also a fix to Resolve ilut and olut format LUTs.

On a brighter note, I have added a 'knee' tool, which very quickly lets you add a smooth, highly adjustable knee to any output curve (including those which already feature a knee). You can set the level at which it kicks in (in stops above 18% gray), the level at which it should reach clip (again, in stops above mid gray), the slope at the clip level, whether you want it to be legal or extended range and how 'smooth' it should be, from hypergamma / cinegamma to oldschool Beta-SP hard knee :-) .

There are a couple of other tools I'm working on, but one thing at a time!

Anyway, I'll post again as soon as I hear from Apple. Thanks,

Ben
 
FYI, Ben, it took a little over a week for update to Adam Wilt's Lightmeter iOS app to be approved. Looking forward to the 2.1 Mac version.

Ned Soltz
 
Hey Ben! :)
Thanks for your reply, when I'll have a chance I will send you the files.
I've download new version (2.0) and likes it a lot!!
Loving this new save function but I have another request ;) It would be great if all settings could be saved and loaded as default. For a temporary fix I have dug in your code and changed FS7 as a default camera ;) (that will do for me for now :) )
 
Hey Ben,

Can't believe how much good work you're continuing to put into the LUTcalc project, I've been a user since a few weeks after receiving my FS-7 back in April, and have enjoyed and appreciated every minute! I have an additional request for a small feature (that may or may not be simple to implement!).

Basically, because I find myself very frequently intentionally over-exposing my Slog3 footage to varying degrees (often up to two stops in low DR environments), I almost ALWAYS end up exporting a "Full set" of exposure-compensated LUTs for use in grading. This takes quite a bit of time to export, go back, change the exp/comp value, export again, AND make sure I name the exported file(s) accordingly. ;-)

It would be great if there was another button next to the 'generate LUT' button, something like 'generate exposure-compensated LUT set', which would automatically kick out a set of LUT variants. The truly ninja solution would then present a dialogue with tick boxes, in which you could select if you want a simple (-1, 0, +1, +2, +3) or comprehensive (-1, -.5, 0, +.33, +.66, +1, +1.33, +1.66, +2, +3?) set of variants.

I personally would be very excited to see that development at some future juncture, but I'll happily keep on plugging and chugging until then.

Again, BRILLIANT WORK MAN!

Cheers,

jason

P.S. I am also among the growing contingent who feel that even the ~£2.50 you're (reluctantly) charging now is still a ridiculously good deal, and would be very happy to donate some more mulah if you provide your PayPal account details or similar.
 
Thanks Jason,

really glad to hear it has been helpful and I'll have a think about how to add that batch generating option.

Apple still haven't got back to me about my 2.1 update, so a reminder to anyone who is using the current Mac OSX version, just keep an eye out that the output range is as you expect.

If anyone fancies having a play around with what I'm working on adding, I've got a 'testing' version of the online app up. Consider the extra bits alpha rather than beta, but please feel free to give them a try.

As a result of a thread on LiftGammaGain about manually entering matrix values in Resolve, I've added a 'custom' option to the recorded and output gamuts. Click on one and a custom colour space panel should appear where you can initially enter XYZ white point and primary values, then click across and get matrices. The kind of thing they have use for on LiftGammaGain, but possibly 'there be dragons' for most people. ;-)

Of more use is that I'm working on a way of (reasonably simply) creating colour responses like LC709A. I'm currently calling the tool 'MultiTone', and as it stands it lets you set saturation values stop-to-stop, with a visual display of the result on Rec709-based primary colours. Eventually, I intend to add options to set one or more colours (or gray) as the base when saturation is set to 0. At one level this would allow you to go say desaturated and blueish in the highlight, but at another if you set all saturations to 0 you would be able to produce a duotone / tritone/ quadtone etc. effect.

As I say, very early, very alpha days, but I'm always keen to hear what people think of my ideas and approaches.

Thanks,

Ben
 
Hi All,

v2.1 has finally been approved on the Mac App Store. Should come through shortly as an update. A couple of bugfixes, plus the knee tool, which I will knock up a video about when I get back from a shoot I'm on.

A couple of new toys I'm having fun playing with seem to be coming together for v2.2 hopefully in the nearish future. Thanks,

Ben
 
Ben , I have a couple of questions.

1- First does it matter where you set the reference white Kelvin when using "White Balance" together with "Preview click for white" ? I would have assumed not, but my experience is otherwise. (I thought that the "reference white" and "New white balance " buttons were just to help you create or understand what a given CTO-CTB shift was doing.)

Backgound: I've been enjoying making new LUT's to cover different lighting situations with LUTCal for my FS7. I'm making LUT's for when I using different LED and Fluorescent key lights, and also for warm room light and various industrial fluorescents.
My workflow is to take a picture of a scene with a person holding a "one shot" chart with white & grey on it in Slog 3 in the FS7. I bring it into the computer and before any color correction or LUTting, I take a screen shot of the video image (either in Catalyst Browse or more frequently i make a Pro Res export first then look at the video in QT.) The screen shot is a PNG that I import into LUTCalc.
In LUTCalc I go to "White Balance" and "preview click for white" and sample the white or grey chips on the one shot card on the Preview window.
Presto - This gives me an instant color corrected LUT for that source - Great .

However I've noticed that if I change the "Reference White" Kelvin and redo the "Preview Click" It often makes a slightly different correction. In fact the closer the Reference White is to the actual Kelvin of the Lightsource I used for the shot, the more accurate the LUT seems to be. Does this make any sense?

(By the way I am not talking about the Kelvin setting in the camera - obviously you would need a different LUT for the same shot if you exposed once at 3200 and again at 4300 or 5600.)

2 - Second question is simple curiosity .
I can't ever imagine using some of the more advanced features of LUTCalc like the PSST and ASC-CDL, but you have obviously put a great deal of work into them . I'm guessing you would never use such dangerous adjustments for a baked in Camera LUT would you?
What uses did you imagine for these settings ? Unless they do things that are very hard to replicate in post I would think that would be an easier route to play with say resolve than bother to make a LUT?

3 - Again curiosity - Have you explained some of the more advanced options anywhere like "Unlock LightSource form New white" or what the "Lamp Nominal Color" is all about . I was guessing that the latter was a setting for typical fluorescents, but since they make no green-magenta changes I am mystified. Have a great desire to know even more about LUTCalc.

Thanks again, and post your paypal address so we can reimburse you more fairly.
 
Hi Leni,

I'm afraid 1 is going to have a bit of a technical answer, but it does also cover 3. 2 is rather easier. For those who don't want a brain ache, move along, nothing to see here :-). Remember, you asked for it... ;-)

First, the workflow you describe sounds exactly how I would check or prep a colour-corrected look.

Mathematically the reference white is just for convenience as a user. When you record a video picture where white looks white you are fixing to one white balance, the white point of the recorded colourspace. In the case of S-Gamut3.cine (or Rec709 for that matter) that is standard illuminant D65. LUTCalc works with mired shifts so that you can set the reference white to whatever makes sense to you. When you do a white balance the camera is shifting everything so that white equates to D65.

When you make a white balance adjustment, you shift along a line known as the 'Planck Locus'. This is the line of 'white' for different colour temperatures and you can see it as the curve in the middle of the xy plots in the LUTCalc previews. That gives the base colour temperature adjustment. If you drew a line perpendicular to the locus on the right hand plot (marked CIE 1960 uv), you get the other adjustment, plus / minus green.

Now whilst a recording has one white point, the temperature of fluoris relative to becomes important. That plus minus green line changes angle as you move along the locus.

As such, if you set your reference white to 5500K but have a lamp which is nominally 3200K (called it's CCT), you will get a different result to setting reference white at 3200K.

In addition, you might film under all fluoris, but I shoot a lot in offices where the lighting is a mixture of daylight and fluori. As such it can be handy to have an 'all fluori' version made with ref white at 3200 and a 'mixed' with reference white at 4300K. The 'unlock' button is so that you can make the plus minus green adjustment at the lamp's correct CCT, but without shifting the overall colour temperature, ie you keep your 4300K look 4300K, but the plus / minus green, the slope of the adjustment line, is correct for the lamp (which might be 2800K and strong enough to produce a colour cast but not so strong as to beat the daylight.

That's pretty fine-grained stuff and not exactly critical, which is why I made it a button to turn on if you need it :-).

Annnnyyyyywayyyyy, on to 2. PSST-CDL I made up because I wanted to see how far I could go in camera, in particular I wanted to see if I could come up with something that would let me do things like the absence of green in 'O Brother Where Art Thou', or the black and white except for skin tones of Pleasantville. Having a live black and white image where the only colour is a coke can entertains me, even if I would have to be seriously b*llsy to bake it in!

Since LUTCalc has been all about starting from an established base, I also thought it would be useful to have a tool which could selectively tone down or emphasise current gamuts. I can't see myself touching the 'colour' control in a normal, baked-in look, but I have played around with saturation - albeit subtly.

I think that the ASC-CDL control is handy. Used carefully you can quickly fine tune contrast with the 'gray' channel and now that I've added a knee tool in v2.1 you can keep a lid on how crazy 'power' and 'slope' can make things.

This post will have sounded horrendous, but hopefully to someone giving it a go LUTCalc should be fairly straightforward for dipping toes, but with the option to geek out wildly if you want to.

Ben
 
Errrr... thanks. Actually I got a bit of it. Heres what I take- The reference Kelvin will subtly change the LUT so Go ahead and pick the reference that gives me the the most neutral Look.

The point about making a LUT for mixed light where there is daylight coming in through the windows but you still need to add some magenta to compensate for the fluorescents inside rang very true to me as a situation I encounter often and I have wondered how to deal with that in a LUT. I figured just make a few LUT's that were say kelvin 55000 and some amount of magenta. Kelvin 5000, 4300 etc.

Have you made up any pack of LUT's to use for fluorescent situations to get you in the ballpark without going nuts with too many LUT's . i.e. "the CameramanBen simplified Flouro pack" . I figure ideally I have my laptop with me and time to scout a location. Take a few tests and then make the LUT's up in about 15 minutes. but often you don't have time. It sure is easy to get confused.

BTW I also wondered where you put your black point for your extended LUT's. I started at 0 but that seemed to be crushed. Now I'm using 1% ( 0.88) but wonder if maybe I should even raise that a point or 2 to get more bits on the lowest steps.

Thanks as always.

Lenny Levy
 
I played with the app trying to get a LUT for custom sLog3 which is similar to CineEI sLog3 RC709A
it works in Resolve, also in FCPX LUT Utility but failed in ColorFinale "Data length does not match declared size"
I sent the LUT to the developer of ColorFinale and he wrote back that the LUT has extra redundant data
He removed the text line marked red and it seems to work. What does this line mean? I am asking but I am also
one of the guys with headache you mentioned above ;-)


TITLE "Custom_slog3toLC709A_2"
LUT_3D_SIZE 65
LUT_1D_INPUT_RANGE 0 1
# S-Log3/Sony S-Gamut3 -> LC709A/Sony S-Gamut3.cine, CineEI Shift 0.00, Black Level 3.98% IRE, Data Input -> Legal Output - Created with LUTCalc v1.9RC17 by Ben Turley August 2015
 
Hi Clermond,

for most LUTs the input range is from 0-1.0. If you want to make say a linear to S-log LUT then 0-1.0 in linear is only a fraction of what the log output's 0-1.0 range. To get around that you can use input scaling. Input scaling says that values outside the range 0-1.0 can be scaled to fit within it.

In my example linear input could be scaled as 0 still equals 0, but 1.0 could actually equate to 42.0, which would cover the whole of S-Log3 range. The Adobe cube spec and Resolve spec use slightly different commands (though LUTCalc automatically understands both).

off the top of my head the one you have there is the Resolve flavour, and is redundant as you are using the default 0-1.0 range. I'll add code to the next update to leave it off if not used, but for now the 'generic cube' preset does not include it. I'll also look into adding that software as a preset to avoid the issue entirely.

You could also suggest to the other software developer that it might be handy to incorporate Adobe or Resolve-flavoured input scaling, or at least better checking of which lines are LUT data and which just notes or instructions. It is good, sensible practice and pretty easy to make a parser ignore instructions that have not been implemented rather than just reject the LUT entirely. A warning is better than a sulk :-).

in practice, it's quite common for that not to happen. When the F5 and F55 first got MLUTs, the camera's parser was hard-coded to read data from line 3. If there was a line of notes more or less (which actually happened with either Resolve or Raw Viewer, I forget which), the data were offset and pictures got a nice red cast! (That has long since been fixed thankfully! ;-) )

Ben
 
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Hi Ben!
Please check you inbox, I have sent you those LUTs through wetransfer. I see two reasons why differences are so big between them two. One is the face that Slog3 version from visioncolor was not produced for Slog3.cine but for Slog3 in custom. The other is that I've made some mistake in setting up Slog3.cine to LogC conversion lut. Would greatly appreciate your help :)
 
Ben,

Is there anyway you could make LUTCalc a plugin for FCPX?

I'd love to be able load LUTs and brew/tweak LUTs in the NLE on live footage especially now you're adding all those colour tweaking controls now.

Just a thought....

I'd expect to pay much more than £3 though!
 
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