F55: F5/F7/F55 LUT primer II: s.gamut3 & s.gamut3.cine

starcentral

starcentral

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Ok this is a good one I promise! (and hopefully it won't cause any stir ups either...)

I bet its not widely known that you can convert S.Gamut3 to S.Gamut3.cine using a 3D LUT made available by Sony not to long ago. This is good to know because the Look Profiles built into the Sony camera (or downloadable separately) are specifically designed to work with S.Gamut3.Cine.

S.Gamut3.Cine is known to be easier to grade and have better color production in the final image, but S.Gamut3 is closer to the native and wide color space of the camera.

So if for any reason you want to preserve the widest color space possible (perhaps like a negative) then you might want to consider using S.Gamut3 in-camera but in post apply two LUTs; the first to convert S.Gamut3 to S.Gamut3.Cine, and the second your Look Profile (Sony LUTs) - then you begin your grading.


Anyone already onto this and do any tests or experiments?
 
Interesting. I might be a bit too busy to do tests in the next couple days, but I'll try to. It would be interesting to see if there is a difference at all between SGamut3 that has been shifted to SGamut3.Cine using a LUT vs. a file that was shot straight SGamut3.Cine.
 
Interesting. Sorry for the ignorant question but does S.Gamut3.cine only work with CineEI mode? When I shoot in 'custom' mode using SLog3 I can't seem to fine S.Gamut3.cine as an option.
 
Thanks for the information but if S.Gamut3.Cine is easier to grade and have better colours why use S.Gamut3? Just for the sake of having a wider colour space? Or are there advantages coming in the future for the wider colour space?

I also have to say that I think Sony made a very smart move bringing the FS7 to a competitive price. Suddenly there's just a mass of S-log3/S-Gamut users bringing the same tools as the F5/F55 which will make S-log3/S-Gamut more mainstream. The same with XAVC which at least to me looks fantastic and can be pushed and pulled around in post without breaking.
 
tbh I get the impression it is just a case of as the camera will appeal to opposite ends of the production spectrum it's just providing a nice starting point for ENG/News/Doc stuff and also narrative styled stuff. Pick your poison.
 
Osslund said:
Thanks for the information but if S.Gamut3.Cine is easier to grade and have better colours why use S.Gamut3? Just for the sake of having a wider colour space? Or are there advantages coming in the future for the wider colour space?

I also have to say that I think Sony made a very smart move bringing the FS7 to a competitive price. Suddenly there's just a mass of S-log3/S-Gamut users bringing the same tools as the F5/F55 which will make S-log3/S-Gamut more mainstream. The same with XAVC which at least to me looks fantastic and can be pushed and pulled around in post without breaking.
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for the answer to your question, here's something for you to read:
http://www.dvinfo.net/article/acquis...s_sgamut3.html
I've played around with the conversion LUT, it works as advertised. The Sgamut3 color space is huge. In fact, there are no color monitors on the market that can display all the colors in Sgamut3.While Sgamut3.cine is somewhat smaller color space, it is also larger than Adobe RGB, re: there are no monitors that can display the color space. For reference, this color space is called Rec2020. Performing a grade on the native Sgamut3 space is similar to trying to grade an HD source on an old NTSC color monitor. What you're seeing on your Rec709 monitor isn't what you'd see if you had a monitor capable of this space.
 
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Yes Osslund, the native SGamut.3 is very wide. We can perhaps think of it as a "negative" from the camera. I think it's fair to say that the SGamut.3.cine is more a derivative from SGamut.3.

What's fantastic is that Sony even thought about this. Its proof these cameras are miles ahead of the others in its category,.. I'm continually impressed by Sony.
 
starcentral said:
Yes Osslund, the native SGamut.3 is very wide.

What's fantastic is that Sony even thought about this. Its proof these cameras are miles ahead of the others in its category,.. I'm continually impressed by Sony.
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I wouldn't say that Sony, necessarily "thought" up Slog3. I think it was driven by sensor technology. They developed a sensor (physics) capable of seeing this gamut, so, they devised a color space capable of describing it. Wouldn't it be curious if someone made a sensor capable of seeing into infrared space (IR)?. Actually, the sensors exist, they just aren't put into consumer cameras. The gamut for a sensor that could see beyond the visible would be interesting, but, of what use?
 
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No problem.

What I meant to say (and maybe I did not say it very clearly) was that it's amazing that Sony thought of creating two color spaces.

One color space (S.Gamut3) wider than DCI-P3 to provide ample room in grading, and then one (S.Gamut3.Cine) for probably the "rest of us" (myself included) which is still slightly wider than DCI-P3 but is much easier for grading and also seems so far to be preferred in terms of color reproduction.

To me the S.Gamut3 is a bit too vivid. Like those crazy colourful demo videos they play in stores to sell 55" flat screens. The cine version of S.gamut3 seems to be a bit more on the side of that pastel color look, well I mean to say slightly less saturated so hence a bit more "realistic" looking - if fair to call it that.
 
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I've spent quite a bit of time understanding the implications of color space, as much of what I do is focused on color grading. The implications of exactly where the primary color vertices lie on the CIE color chart are of high importance when it comes to grading colors on a Rec709 calibrated monitor. Looking at SGamut 3 and SGamut3.cine on the CIE chart, I think one can see that Red and Blue looked like they are scaled up from Rec709. But, looking at the Green vertex for SGamut3, it's clear that it's not just scaled, it's actually displaced to the left , relative to Rec709 Green vertex. This is why trying to color grade an SGamut3 image is so hard. It just doesn't fit the Rec709 color monitors we all work with. If one looks at the SGamut3.Cine green vertex, you can easily see that it is displaced back to look like a scale up from Rec709.

That's one point about the differences. But, also, the "neon" look that one sees with Slog3, probably is the result of a conversion from Slog3 to Rec709. The out of range colors are remapped to Rec709, which essentially a boost in the saturation when mapped to Rec709(rather than clip the out of range colors). Slog3.Cine is a smaller color space than Slog3, so there is less saturation boost when converted to Rec709. Plus scaling green is less mathematically complex.

I can't help but wonder how really useful the Slog3 color spaces are, given that conversion to Rec709 is not trivial. For a lot of reasons, I continue to shoot in Slog2.
 
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cuervo said:
I've spent quite a bit of time understanding the implications of color space, as much of what I do is focused on color grading. The implications of exactly where the primary color vertices lie on the CIE color chart are of high importance when it comes to grading colors on a Rec709 calibrated monitor. Looking at SGamut 3 and SGamut3.cine on the CIE chart, I think one can see that Red and Blue looked like they are scaled up from Rec709. But, looking at the Green vertex for SGamut3, it's clear that it's not just scaled, it's actually displaced to the left , relative to Rec709 Green vertex. This is why trying to color grade an SGamut3 image is so hard. It just doesn't fit the Rec709 color monitors we all work with. If one looks at the SGamut3.Cine green vertex, you can easily see that it is displaced back to look like a scale up from Rec709.

That's one point about the differences. But, also, the "neon" look that one sees with Slog3, probably is the result of a conversion from Slog3 to Rec709. The out of range colors are remapped to Rec709, which essentially a boost in the saturation when mapped to Rec709(rather than clip the out of range colors). Slog3.Cine is a smaller color space than Slog3, so there is less saturation boost when converted to Rec709. Plus scaling green is less mathematically complex.

I can't help but wonder how really useful the Slog3 color spaces are, given that conversion to Rec709 is not trivial. For a lot of reasons, I continue to shoot in Slog2.
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I'm a newbie when it comes to this color stuff. How do you see/determine the observations you're making? In a program like Resolve?

Personally, I've found it easier to work with Slog3. Not sure if it's because of the Sony-provided LUTs or the fact that it seems more linear (not as much highlight compression)... just easier for me to work with.
 
jshbckr said:
I'm a newbie when it comes to this color stuff. How do you see/determine the observations you're making? In a program like Resolve?

Personally, I've found it easier to work with Slog3. Not sure if it's because of the Sony-provided LUTs or the fact that it seems more linear (not as much highlight compression)... just easier for me to work with.
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Josh,
Not so much observation as much as understanding the technicalities of what's going on. I will point out that it's rather pointless to make ANY judgments about image quality by looking at the display in an editing program, whether it's resolve, media composer, PP, or FCP. Even if you, as an editor, have a high quality studio monitor that's been calibrated to Rec709, the image you're editing to is not what you'll see on the final master. It's closer, but, not exactly right. There's a ton of opinion expressed without much technical truth. Even Sony is not entirely forthcoming with application support for their new gamuts.

Case in point: when HD (Rec709) was first released, everyone scrambled to find a Rec709 calibrated monitor because the colors weren't right when viewed on an old CRT NTSC monitor. How did people know the colors weren't right? because the technical description of Rec709 was different than NTSC. Then, as Rec709 monitors hit the market, comparisons were made that showed the differences. And now, we're starting to use Sgamut3 with an LC709A LUT. That's a color space designed for Rec 2020. And we're doing color grading on a Rec709 monitor? The technical description of Rec2020 says that won't work.

As this stuff gets more and more technically evolved, it takes a DIT to be able to produce an image master that represents the cinematographer's or director's vision. Maybe this is a good thing.....as it takes production out of the garage and back into a craft.
 
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