Do you think Slog 2/ S-Gamut3.cine need a LUT to convert to Rec 709?

T

theprestige

Active member
I'm just wondering what people think about the grading a colour space like S-gamut3.cine from scratch with a flat picture profile like SLOG 2 or something. I know for S gamut and Sgamut3 you'd definitely need a technical LUT to convert the colour space, but from what I understand, S-gamut3.cine is supposed to be much more grade friendly and thus doesn't really require a LUT.

What are your thought and opinions on this?
 
My preference is to grade without using a LUT - I shoot Slog3.cine 95% of the time - but then if I'm doing a quick turn-around type job that requires lots of post work - I'm using a LUT (exposure compensated) to get in the ballpark before tweaking that grade. If knowing ahead of time the director or client wants a certain "look" - then it's nice also to have a LUT to monitor on set and light & shoot to that (knowing tweaking is still available in post).
 
markfpv said:
My preference is to grade without using a LUT - I shoot Slog3.cine 95% of the time - but then if I'm doing a quick turn-around type job that requires lots of post work - I'm using a LUT (exposure compensated) to get in the ballpark before tweaking that grade. If knowing ahead of time the director or client wants a certain "look" - then it's nice also to have a LUT to monitor on set and light & shoot to that (knowing tweaking is still available in post).
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Do you find s-gamut3.cine fairly easy to grade then if you know you've got time on your hands?
 
Yes - I do. And I've only starting shooting log in the last 2 years so am fairly new to Resolve (but also use Color finale). There's a bit more personal satisfaction when not using a LUT ( and of course once you do this a few times, you can then create your own LUTs based on your grade.
 
Do you think Slog 2/ S-Gamut3.cine need a LUT to convert to Rec 709?
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I previously wrote a long reply but realized I misunderstood your question.

s-gamut3.cine is part of the 3 s-gamut family. It looks like Sony added some yellow but all 3 share the same purple-ish looking reds as if they're expecting to be converted with a technical LUT to correct that. Pro and Movie color reds look accurate.

That said, if you can get a good look that you're happy with without using a LUT, why not?

However, if I understand what I read, Rec.709 colorspace is desired so that colors appear accurate on tv sets that can't display more than X amount of colors and X amount of highlights and black gamma (16-235). I might be wrong about that. What is the final destination of your project? If it's to be watched on an iPad or Vimeo does it really matter?
 
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In normal circumstances, you should apply a technical LUT to de-log the footage before grading. I use my own version of Sony's SGamut3CineSLog3_To_LC-709TypeA LUT as a base 95%.
 
Viscount Omega said:
I previously wrote a long reply but realized I misunderstood your question.

s-gamut3.cine is part of the 3 s-gamut family. It looks like Sony added some yellow but all 3 share the same purple-ish looking reds as if they're expecting to be converted with a technical LUT to correct that. Pro and Movie color reds look accurate.

That said, if you can get a good look that you're happy with without using a LUT, why not?

However, if I understand what I read, Rec.709 colorspace is desired so that colors appear accurate on tv sets that can't display more than X amount of colors and X amount of highlights and black gamma (16-235). I might be wrong about that. What is the final destination of your project? If it's to be watched on an iPad or Vimeo does it really matter?
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Final Destination is usually web.
 
Well, if you don't bother with a technical 709 conversion LUT you could add a 16-235 plug-in at the end of your final effects chain to limit your highlights and shadow areas so they appear normal anywhere. I use Sony Vegas and it has one called "Broadcast Colors". It brings things into the 16-235 range without the severity of a LUT. Not sure if other NLE's have something similar though. Maybe something called "Levels"?
 
On Premiere, you can use these curves. They work better than LUTs for me, and they can be adjusted to taste.
(some presets are for changing exposure, the ones that add contrast without clipping highlights or shadows are what you're looking for)
 
Technically speaking if your footage is in a colorspace that is not the same as the colorspace you are grading in you should use a coversion lut. The conversion from s-gamut3 to rec709 will not be accurate if you don't use a proper lut or color transformation matrix. You could end up with funky colors if you don't that can be difficult to grade out. In the end if it looks good it doesn't really matter how you get there but it is almost always easier to start with a good neutral image when grading. For me always the first order of buisness is a proper conversion lut.
 
(I don't shoot with sgamut or sgamut3.cine, I use these settings, and with them a simple curve is all you need to get nice colors with viewable contrast)
(my problem with LUTs is that there's something wrong in my software workflow, and while everybody else uses LUTs happily, I always end up with banding and noise and ugly images if I use LUTs, that's why I created those curves)
 
Lots of good advice. Samuel, i've actually come across the settings you've posted awhile ago, i've yet to test them out myself but i've heard good things from people who experimented with them, and obviously your videos always look great too. I'll probably give that setting try, maybe even today.

I've actually been using cine 4/sgamut3.cine for low light/interior shoots, and have been impressed with the images, no conversion needed at all. But i'm a dynamic range whore and I really wanted 'accurate' colours.
 
(I've never used sgamut3.cine, it may be better than my settings; my a7S didn't have sgamut3.cine, and my RX100 IV doesn't have it either)
(I may rent an a7S II for a project in september, I'll test the hell out of it if there's time to play)
 
Tried importing the curve via lumetri greys it out on my computer. Tried just opening the curve too, but that doesn't to work either so I colour corrected from scratch. I'm quite impressed with it, Samuel. It's a decent alternative.
 
I don't use it on lumetri, it's just a "RGB curves" preset that appears on the list of available effects.

In any case, there's not a lot of magic in there:
curve1.jpg
curve2.jpg
curve3.jpg


So yes, whatever you are doing, it's probably very similar to what I'm doing.

Glad you like the results :)
 
theprestige said:
I'm just wondering what people think about the grading a colour space like S-gamut3.cine from scratch with a flat picture profile like SLOG 2 or something. I know for S gamut and Sgamut3 you'd definitely need a technical LUT to convert the colour space, but from what I understand, S-gamut3.cine is supposed to be much more grade friendly and thus doesn't really require a LUT.

What are your thought and opinions on this?
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What NLE are you using to grade in? Generally I don't use LUTS. If I did it's one I made for the camera or a simple de-log one that was also camera specific. I use Colorista III in Premiere Pro because it seems to handle color better than Lumetri does. I use the the 3 color wheels and balance the blacks and highlights then go to town on color grade. It's not complicated or takes very much time. I'm not big on look LUTS that everybody is selling these days. I suppose it's an easy way to get a look but you don't learn anything about how to achieve the looks. YMMV.

I do think LOG shooting has become somewhat over used for situations that don't require it and makes the workflow overly complicated for no good reason. If you end up with a REC709 look then why shoot log? If the scene isn't contrasty you don't need to shoot flat. Anyway just because you can doesn't mean you should.

With the a7rII I tend to shoot CINE 4 with Cinema and some tweaks to Color Depth. This gives me a nice image that has some room to work with in post and the saturation is about right for my taste. Really easy to shoot and grade. The codec isn't that great. It's okay so I prefer to not shoot super flat like I would with my FS7. Lots of variables for me. Camera codec, scene type and how much work do I want to put in the grade. These are the questions I ask myself before I shoot. It's never a one size fits all thing for me.

Also remember when grading an image you are essentially damage it. The more you do the more noise will be added. Plus add in a somewhat weak codec and you get banding with the blue channel when you bring back saturation or change the hue.
 
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Erik Naso said:
What NLE are you using to grade in? Generally I don't use LUTS. If I did it's one I made for the camera or a simple de-log one that was also camera specific. I use Colorista III in Premiere Pro because it seems to handle color better than Lumetri does. I use the the 3 color wheels and balance the blacks and highlights then go to town on color grade. It's not complicated or takes very much time. I'm not big on look LUTS that everybody is selling these days. I suppose it's an easy way to get a look but you don't learn anything about how to achieve the looks. YMMV.

I do think LOG shooting has become somewhat over used for situations that don't require it and makes the workflow overly complicated for no good reason. If you end up with a REC709 look then why shoot log? If the scene isn't contrasty you don't need to shoot flat. Anyway just because you can doesn't mean you should.

With the a7rII I tend to shoot CINE 4 with Cinema and some tweaks to Color Depth. This gives me a nice image that has some room to work with in post and the saturation is about right for my taste. Really easy to shoot and grade. The codec isn't that great. It's okay so I prefer to not shoot super flat like I would with my FS7. Lots of variables for me. Camera codec, scene type and how much work do I want to put in the grade. These are the questions I ask myself before I shoot. It's never a one size fits all thing for me.

Also remember when grading an image you are essentially damage it. The more you do the more noise will be added. Plus add in a somewhat weak codec and you get banding with the blue channel when you bring back saturation or change the hue.
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I'm using Premiere Pro CC 2013. I too am using Colorista III, Samuel H actually recommended it and I haven't looked back since using it. I agree with you, it's great and colours better than Lumetri and appears to have a easy enough workflow.

I guess REC709 just seems like a solid starting point for LOG, and i've been told/read that it's the best place to start if you want to get the most out of it. But yeah, you dont have to shoot log all the time, but I do find the dynamic range really useful when i'm out shooting in daylight or any situation where I don't feel the need to boost the ISO. That said, I too like Cine 4 but use Sgamut3.cine with it usually and have been very pleased with the results. I only use that in doors in low light situations and it's yet to disappoint.

So if I have this right, you never boost the saturation because of the cinema profile you use?
 
- Colorista III is the best $$$ I've spent in the last few years.

- I use Cine4 if I need high ISO, but if there's enough light I always go slog2. Yesterday I shot at a park: sunlit background, but talent in the shadow to avoid ugly shadows from direct sunlight. As usual, it was just me and the talent, so, no lights, no diffusers, not even a reflector. I would have loved to have just a stop more DR than what I get with slog2.
 
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