FS7: LUTCalc v2.54

C

cameramanben

Well-known member
Hi All,

after a pretty busy summer filming, I recently got back into looking at LUTCalc, in the past few weeks I have uploaded several updates. I realised that I hadn't mentioned any here, and since I usually write a post, I thought I'd bring things up to date.

With v2.5 I added a 'Black Gamma' tool, which can be used to adjust the contrast in the shadows. As with other tools, I have it designed around the real-world stop level (as opposed to the recording IRE in camera), but hopefully it is pretty straightforward to play with and should be fairly flexible. With this I think that LUTCalc now includes all the tools you might expect to have in-camera.

Also with v2.5 I fixed a small but significant bug. If you use LUTAnalyst to read in and convert a LUT, with v2.4 the output gamma and gamut should have been automatically setting to the LUTAnalyst option. Unfortunately, the preview window was not automatically displaying the colour or gamma side of things. v2.5 fixed that.

After hearing from users about Canon C-Log3 and RED Log3G10, I looked up the background (kindly getting preliminary drafts of the Log3G10 white paper from Graeme Natters at RED) and added both as gamma options, plus the REDWideGamut that goes with the RED log curve with the updates to v2.53. The last update (v2.54) was because the work-in-progress RED spec had changed a little (and, yes, because I had let a little bug slip into it on the first go! ;-) )

I've also had a read of the Rec2100 spec for implementing PQ and Hybrid-log for HDR. I haven't had a chance to properly play with a PQ monitor, but I know from feedback that things were not playing well, even though the code was developed straight from the Dolby maths and generated LUTs which matched up with Resolve's. I realised from the Rec2100 documentation that it talks about gamma correction on top of the base PQ response, so I've tentatively incorporated that. If you want to give it a go, the option is 'Rec2100 PQ'. Very keen to hear from anyone who can test that out!

Please do give me feedback, good or bad, and I do have a few things I'm looking to work on for another update, though that may take a while longer. Hoping to make things smoother, smaller and generally more efficient, rather than adding more stuff!

Thanks,

Ben
 
Hey Ben, thanks for the info, that's all good stuff to be aware of, and thanks again for your ongoing commitment to such a goddamned useful tool!

Zero negative feedback from me, but one potential wishlist feature that would help me (and I imagine many others) a lot...

As I'm almost always using a version of my LUTs for on-camera monitoring, and because (like many others), I often like to ETTR to varying degrees when shooting log, I almost always farm out an exposure-compensated series of any LUT I create in LUTcalc. It always crosses my mind as I'm repeatedly clicking through the menus and modifying filename suffixes that it would be a task much better suited to my computer! If you could have a button next to 'export LUT' called 'export LUT set', which then brought up a dialogue asking if you wanted a whole, half, or third stop increment set, and then saved and named the whole set in one click, that would be, to accurately use an often abused word... Awesome.

Just a thought on the train home after a long day.

Cheers either way!

Jason
 
Hey Ben,

Thanks for all your continuing hard work on this.

Because I find myself being a bit overwhelmed with options whenever I look at it, do you have any simple tutorials around?

Say I want to make some Slog3/SG3.cine FS7 Cine-EI specific exposure compensated LUTs both for monitoring on a SmallHD702 and for use in Resolve later, is it simply a case of importing/analysing a LUT, lowering the EI by a stop or 2 and then exporting again without touching anything else?

I think I've done this but not sure if I've missed an important step or 2.

Thanks again, from one Ben to another.
 
Hi Ben,

that sounds generally right. The only thing I would say is that different bits of software and hardware expect different ranges and sometimes have limits on the mesh size and whether they are happy to have out-of-range output values, so it is best to make both a Resolve-specific version and a SmallHD one, using the Resolve preset (a 'Grading LUT'), then clicking over to 'Camera Monitor LUT (MLUT)' and selecting the SmalHD preset.

For everyone else, yes, but what do you really want? :-) This is a very good idea and I have thought about it before, but considering how simple it sounds it needs a bit of thought, both to make it work and to make sure I don't break anything else. I'll get on it.

Thanks,

Ben
 
About the only thing I'd like to see in LUTCalc is that it remembers my Custom Preview Images between sessions. Perhaps if it were possible for LUTCalc to remember several custom images that I can quickly switch between that would be awesome too...!

Cheers Ben for taking the time and effort to produce this incredibly useful tool.
 
Right, so this is REEEAAALLLLYYY early and will need plenty of testing before I let it near a stable release, but I think that I have had a reasonable stab at adding batch generation of exposure adjustment LUTs. You can try it online here in the 'testing' version:
LUTCalc Online Testing

Alongside the 'Generate LUT' button is now a 'Generate Set' button. This should open up a window where you can set the minimum and maximum stop shifts you want to cover, and then the step size between LUTs in fractions of a stop. The default is set to the Sony CineEI range - -2 to +2 stops in 1/3 stop steps.

The LUTs generated should have the filenames and titles set as normal, but with the exposure adjustment appended. To avoid possible issues with decimal points in titles, 'p' is used, ie -1p33 means minus 1 1/3 stops adjustment.

Again, I've only just knocked this up today so very experimental and at the moment I'm trying to make sure I haven't done anything bad to the 'normal' Generate LUT flow, but please do try it out and let me know if I'm on the right lines,

Ben
 
Whoop whoop! CameramanBen has done it AGAIN!!! :-D

Just tested the creation process on the HTML version, and seems to work well. Will report back ASAP as soon as I've had a chance to load them into my Gratical and check them on the same footage in Resolve as well.

Thanks Ben, you are THE MAN!!! :-)

jason

P.S. Oh yeah, and one more TINY request ... Please re-post a tip-jar link on this thread NOW!!! ;-)
 
I' ve mentioned this, before, but, perhaps it's worth a mention here. The single biggest choice that, usually, requires I go thru a trial and error process, is knowing what LUT I/O Range to select. It's probably impossible to foretell what output range a particular user needs, but, I wonder if there isn't some method to detect the I/O Range of a particular LUT that has been analyzed.
 
Thanks All,

fingers crossed I haven't done anything silly with the new batch code and once the tyres are well kicked I'll work on getting an update out.

cuervo, believe me I feel your pain and can't understand why I have yet to come across a LUT format which includes a mechanism to make that intent explicit and clear (I do have LUTCalc include it in a human-readable 'notes' line - starting # - in cube files).

I would say that D->L or D->D cover the vast majority of cases I've come across, followed by L->L,

Ben
 
Still trying to figure out how to open a LUT and only change it to -1 or -2 stops without changing anything else and save it for use on the Odyssey 7Q, anyone have an idea?
all sorts of camera settings and stuff show up and none that are ever really fitting ;)
 
Hi dmitrizigany,

if you have a LUT that you want to adjust, you first read it in using the 'LUT Analyst' Tool. This is the box on the bottom left of LUTCalc. It should be set to 'Import New LUT'. Click on the box to choose the LUT to load in.

Once you do that, the box changes and shows several options. Presumably these are the ones you are really asking about. First off is 'LUT Title'. Some LUT formats allow for the inclusion of a title within them. LUTAnalyst will look for that. Alternatively, you can set this to whatever you want.

Any LUT is designed for use with a particular recording setup. Use a LUT designed for LogC and Arri Wide Gamut on an Arri camera with a recording made in S-Log3/S-Gamut3.cine on a Sony and it will probably look OK, but it will look different.

To make sure that the LUT being read in is converted for use with whatever your intended camera setup is, LUTAnalyst asks what gamma and gamut the original is deigned around. If your LUT was made for a Sony camera, this will generally mean choosing S-Log3 and S-Gamut3.cine or S-Gamut3, or S-Log2 and S-Gamut from the drop-down menus in the LUTAnalyst box. Hopefully, that should be fairly straightforward.

Next is Analysis dimension. This is the size of LUT which LUTCalc uses internally to do its calculations. Leave that as 65x65x65 - there generally isn't a reason to change that.

The somewhat fiddly one is 'LUT Range'. Depending on the software used to create the LUT you are reading in, there may well be different expectation of what range will be fed into the LUT, and what range the output should be treated as. Unfortunately, no LUT formats that I have yet come across include a way of specifying this explicitly, so there is a degree of 'suck it and see'.

Try out the default setting first - it is the way that Sony's own look profile LUTs are arranged. Click 'Analyse'. After a few moments the chart on the right should change to reflect the LUT that you have just read in, and in the box towards the top left 'Out Gamma' and 'Out Gamut' should have changed to show 'LA - ' followed by the title of the LUT read in by LUTAnalyst.

If you look at the chart (Stop/IRE) and black appears to be below 0% IRE, this tends to be a clue that the range is incorrect. Another is that white is not where it is expected to be. If you expect white to be heading towards 100%, but it appears to be nearer 109% or elsewhere, you may well need to try a different range setting. Change it in the LUTAnalyst box and click 'Re-Analyse'. The vast majority of the time in my experience it will be a choice between D->L and D->D.

If all is now good, you can use the 'LA - ' options as with any other of the built-in options and forget about the LUTAnalyst box. If you want to create a LUT which reverses the gamma / tone curve side of you read-in LUT, you can also choose 'LA - ' as a 'Rec Gamma' or input option. This can be a way to reverse accidentally baked-in footage, or to make a LUT for a non-log recording such as WideDR on a C300.

For more details about general use of LUTCalc, there are details and instructions about all the options by clicking 'Instructions' just above the chart, and on the website - lutcalc.net - I have posted a couple of introductory videos.

Hope that helps,

Ben
 
Hi All,

I've added a couple more things and made a couple of adjustments to LUTCalc testing . They are:
* Feature Change - White and Black clipping can be set individually, and either to the LUT's output range, or always legal.
* Feature Change - The 'Log Info' information button is now 'Tables', and shows IRE and 10-bit values for the current output gamma, both for various common reflectances and for each of +/- 8 stops around 18% gray.
* Feature Change - 1350% reflectance has been replaced by 'Clip', to reflect the white clip level of the currently selected camera.
* Bugfix - Fixed broken ACEScc input code. ACEScc as a 'Rec Gamma' option now works as expected.

along with:
* New Feature - Batch-generate sets of exposure compensation LUTs across a user-selectable EI range and step size.

which you already know about. Let me know your thoughts, and once I'm happy that things are solid, I'll push out an update. Thanks,

Ben
 
Hi All,

another day, another update to LUTCalc Testing!

I've had a few messages and queries about LUTs involving the basic 'Rec709' gamut option producing chroma clipping effects. That option is the basic matrix from the ITU documentation, so going from a wide gamut to a narrow one - particularly with a relatively narrow gamma - stands a good chance of saturated colours, and even of pushing colour channels into the superblacks. LUTCalc by default has not clipped or limited, instead offering alternative options, but it seems clear to me that it should try to keep things sane, but then offer the option to switch off the safeguards.

The latest additions are my attempt at that. This is very new and needs testing to prove it's worth.

First off, I've changed the 'Hard Clip' option so that it is now a drop down. I know, more complicated ;-). But actually, the idea is that now you can choose whether black, white, both or none are clipped. Furthermore, the default is to clip black only. This should reduce the chance of narrow gamuts such as Rec709 pushing saturated colours from wide gamuts into the superblacks, with whatever results or artefacts. If you need the unclipped maths, the option is there to turn it off, but I think that this default should be better and easier for most people.

Whilst on the clip issue, if the output is set to 'Data Range' and you have any clipping set, a little tick box will now appear marked 'legal'. This will make the clipping restrict things to legal range. The charts and preview will now reflect clipping choices, so it should be clearer when you try it than when I try to explain it! :-)

Now, on top of that, I have had a stab at what I'm calling 'Gamut Limiter'. This brings up a dropdown marked 'Display' with two options - 'Rec709 / sRGB' (which share primaries and white point) and 'Rec2020 / Rec2100' (likewise). This attempts to limit the saturation within the chosen displays vectorscope range, whilst maintaining luminance. It is applied after all other corrections and transformations, so the most significant effect would be to bright colours at luminances above white clip. Strictly that stuff is by definition outside of the colour space, but this way there is still image data, but hopefully a reduced chance of weird saturated colours.

This last one is something I have just come up with to try to maintain LUTCalc's separation of gamma and gamut within colourspaces, and I have only tested it out on the preview defaults (Rec709 Gamut and CIE 1932 combined with the saturation adjustment providing as much saturation as I care for). With some other stuff, notably batch creation of sets of exposure adjustment LUTs there has been a fairly substantial amount of coding done, so this is definitely LUTCalc testing (!), but I would appreciate any feedback, even (especially) if it draws my attention to something I've broken.

I'm going to kick the tyres whenever I have a chance as I'm keen to get out a proper update, but the day job is looking likely to get busy, so I'll take any help I can get. Thanks,

Ben
 
Thanks for you very long reply, Ben!

This is really a bit over my head. My issue is, I have the ImpulZ LUTs. And As I understand it, the FS700 has a slight variation of it's own of SLog2, Impulz comes with both Sony SLog2 and Sony FS700 SLog2 versions of their LUTs... When I open LUTCalc, and open a LUT and using the LUTAnalyst... It reads the LUT byt all the settings in the LUTAnalyst box read S-Log3, S-Gamut.cine etc... So I change that to S-Log2 and S-Gamut... but going up the table On Top is Camera... There's no FS700 to choose. What should I choose here? I want to change the Stop Correction to -1 and/or -2. But the results differ depending on what camera is choosen above.
Going down further, again all is set to SLog3/S-Gamut.cine3... changing this to Slog2 and S-Gamut... But is that FS700s version?
Out Gamma and Out Gamut are set to All... and then LA - and the name of the LUT I analysed... What should be set here?

I just want to make sure NOTHING except for the stop correction is changed in the LUT... But all these settings look like they're changing things... Maybe there's no way to do this?

Maybe my confusion is mostly because there's not the correct choices available? There's no FS700 camera to choose, no FS700 SLog2 and no Odyssey 7Q... so it feels like any option is wrong...

cameramanben said:
Hi dmitrizigany,

if you have a LUT that you want to adjust, you first read it in using the 'LUT Analyst' Tool. This is the box on the bottom left of LUTCalc. It should be set to 'Import New LUT'. Click on the box to choose the LUT to load in.

Once you do that, the box changes and shows several options. Presumably these are the ones you are really asking about. First off is 'LUT Title'. Some LUT formats allow for the inclusion of a title within them. LUTAnalyst will look for that. Alternatively, you can set this to whatever you want.

Any LUT is designed for use with a particular recording setup. Use a LUT designed for LogC and Arri Wide Gamut on an Arri camera with a recording made in S-Log3/S-Gamut3.cine on a Sony and it will probably look OK, but it will look different.

To make sure that the LUT being read in is converted for use with whatever your intended camera setup is, LUTAnalyst asks what gamma and gamut the original is deigned around. If your LUT was made for a Sony camera, this will generally mean choosing S-Log3 and S-Gamut3.cine or S-Gamut3, or S-Log2 and S-Gamut from the drop-down menus in the LUTAnalyst box. Hopefully, that should be fairly straightforward.

Next is Analysis dimension. This is the size of LUT which LUTCalc uses internally to do its calculations. Leave that as 65x65x65 - there generally isn't a reason to change that.

The somewhat fiddly one is 'LUT Range'. Depending on the software used to create the LUT you are reading in, there may well be different expectation of what range will be fed into the LUT, and what range the output should be treated as. Unfortunately, no LUT formats that I have yet come across include a way of specifying this explicitly, so there is a degree of 'suck it and see'.

Try out the default setting first - it is the way that Sony's own look profile LUTs are arranged. Click 'Analyse'. After a few moments the chart on the right should change to reflect the LUT that you have just read in, and in the box towards the top left 'Out Gamma' and 'Out Gamut' should have changed to show 'LA - ' followed by the title of the LUT read in by LUTAnalyst.

If you look at the chart (Stop/IRE) and black appears to be below 0% IRE, this tends to be a clue that the range is incorrect. Another is that white is not where it is expected to be. If you expect white to be heading towards 100%, but it appears to be nearer 109% or elsewhere, you may well need to try a different range setting. Change it in the LUTAnalyst box and click 'Re-Analyse'. The vast majority of the time in my experience it will be a choice between D->L and D->D.

If all is now good, you can use the 'LA - ' options as with any other of the built-in options and forget about the LUTAnalyst box. If you want to create a LUT which reverses the gamma / tone curve side of you read-in LUT, you can also choose 'LA - ' as a 'Rec Gamma' or input option. This can be a way to reverse accidentally baked-in footage, or to make a LUT for a non-log recording such as WideDR on a C300.

For more details about general use of LUTCalc, there are details and instructions about all the options by clicking 'Instructions' just above the chart, and on the website - lutcalc.net - I have posted a couple of introductory videos.

Hope that helps,

Ben
Click to expand...
 
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