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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

skintone

Matt Ryan said:
Anyone have these converted to .cube? Sorry but I've given up after 2 hours worth of attempts. Not getting it right apparently.
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I was unaware of this thread.. I got the luts from Björn from another thread. But they are too many to convert, so tell me, which one you want. I know how to make a 3d .cube from a 3dl, but you have to tell me what I am grading from.. RedLog, Redlogfilm, Redgamma 1,2,3??, what color space also. I'll make one for you right away..
 
Pablo Moreno said:
I was unaware of this thread.. I got the luts from Björn from another thread. But they are too many to convert, so tell me, which one you want. I know how to make a 3d .cube from a 3dl, but you have to tell me what I am grading from.. RedLog, Redlogfilm, Redgamma 1,2,3??, what color space also. I'll make one for you right away..
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Hey Pablo, Thank you. I got the Kodak but looking for the Fuji now. Redlogfilm is usually where I start, then use an input lut to go to logC.
 
Steve Sherrick said:
Yes, lighting variations would definitely be part of the test. In fact, we'll probably attempt to do it wrong as an example. :-)
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In terms of sharpness. Daylight sources with this sensor will render sharper images. Kino's litepanels, hmis, will all make the images look sharper. In fact this is true with most digital sensors or pretty much any video camera. They like they blue light.

One test you should run is this.

Get about a 10K tungsten source and progressively gel it with, 1/8th, the a 1/4, then 1/2 blue and check out the sharpness or difference in sharpness of the image. I suggest a big source so you can offset the slight light loss and not be wide open, which will always make things softer.

Then just put a 1x1 light panel in place on the same scene/subject and watch how crispy sharp the image gets (even tough it can be a soft source).

the trick when it comes to skin is to get the combination of a good grey value, along with the softness tungsten sources create in the r3d. I always find that about 3800 - 4400k with a blued up tungsten source can give that effect, but aperture also has an effect on perceived sharpness and how much the skin tone gets "flattened out".

These, of course, are other factors when it comes to skin. Questions to consider? Is the source lighting making the sensor sharper? What do I want to do to that source light to get it in that mellow skin range that the camera sees?

david
 
I Don't understand why no one want to realize that this is the one and the only way to correct (once for all) the Red skintones issue, everybody is fuzzing about.. with a color lookup table (LUT).. Only a few of us like Björn and a few others have been trying to tell you this, for quite sometime now with no succeed, you guys just make jokes about it when we mention it.. I don't even see red engineers paying much attention on this.

But I'll tell you a secret (Jim), regardless you want to believe it or not.. the reason why Canon cameras and Alexa and others, look the way they particularly look, is because, the secret lies beneath a special color lookup table they have, believe me, they just don't want you to know that. (Dammed, I just revealed my secret!). There you go.. Kodak film without the grain down there..


Kodak 2393 log2HD (lifted mid tone with luminance curve and pumped saturation)
Kodak_1.1.5_700.jpg
 
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Pablo Moreno said:
I Don't understand why no one want to realize that this is the one and the only way to correct (once for all) the Red skintones issue, everybody is fuzzing about.. with a color lookup table (LUT).. Only a few of us like Björn and a few others have been trying to tell you this, for quite sometime now with no succeed, you guys just make jokes about it when we mention it.. I don't even see red engineers paying much attention on this.

But I'll tell you a secret (Jim).. the reason why Canon cameras and Alexa and others, look the way they particularly look, is because, the secret lies beneath a special color lookup table they have, believe me, they just don't want you to know that. (Dammed, I just revealed my secret!). There you go.. Kodak film without the grain down there..

Kodak 2393 log2HD (lifted mid tone with luminance curve and pumped saturation)
Kodak_1.1.5_700.jpg
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This looks ok but bear in mind this is done under ideal conditions for RED - wide spectrum daylight.

3D LUTs might be able to get you most of the way there (and are an extremely useful tool).

But you can't just do one LUT that works for all lighting situations and subject matters.

Yes, you can get quite close if you have one set of secondary corrections (or 3D LUTs) for daylight and one set for tungsten and then blend between those.

BTW, his hair looks blue in that one.

This is something I hit a lot: when I make skin look normal with RED, the hair goes blue and I have to do a secondary to fix that. Anyone else hit that?

Bruce Allen
www.boacinema.com
 
Whoa, wait, so these are NOT from RLF to Film LUT? You need to go from RLF to LogC input LUT first and then go to the film output LUTs to get proper colour/properties?
 
Mike P. said:
Whoa, wait, so these are NOT from RLF to Film LUT? You need to go from RLF to LogC input LUT first and then go to the film output LUTs to get proper colour/properties?
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No, Bob and I are using SpeedLooks which uses a LogC start. The LUT's Bjorn posted are to convert RLF to film LUT.
 
Blair S. Paulsen said:
I think David B. makes a very salient point about the influence of the lighting CRI (color rendering index) on skin tones. I work with a producer who was unhappy with skin tones and perceived sharpness on some green screen stand ups so he asked me if I thought the lights we were using might be the culprit. I suggested we rent some Kinos for the next shoot and the improvement was substantial. Perhaps the concept that more precise readings of color made possible by modern imaging platforms makes lighting quality more critical is the key.
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Or maybe the modern imaging platforms have new distortions in their color rendering - and if a spike in the lighting happens to line up with a nonlinearity in the color filters or color processing, or maybe just the filters weren't optimized for that kind of light, you get a compounded error?

100% agree that right now when you are filming, you have to be very careful about lighting choice. But I don't think it's because the sensor is insanely accurate. I think a lot of digital cameras just can't handle certain kinds of light well. I think that future sensors will hopefully be able to do better under challenging lighting conditions.

If the human eye can somehow pick up a natural color out of terrible lighting, a truly precise, possibly multi-spectral sensor of the future should be able to do the same thing, when armed with the appropriate transforms, no?

Mike P. said:
Speaking of lighting, I find that skin tones lack "thickness" when using tungsten, which I presumed was solely because of the lack of blue (you can see it in the skin tones; lacking sharpness and strength compared to the other two channels). When you white balance tungsten the entire blue channel (which is underexposed compared to R and G) gets bumped up on the entire image and not just the skin tones/mids. It's obviously very noticeable when the amount of light is limited, otherwise it goes away when you downscale. I still haven't tried LED lights, but I was fairly optimistic (maybe too much so) that they'd play nice with RED/CMOS sensors (they have a tendency to go green though don't they?)
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I do agree that the blue channel is an issue with tungsten if you don't feed it with a lot of light - hopefully with Dragon this will be hugely improved since the sensor will as a whole be higher-performance.

The only issue is that a lot of LED lights do not produce an even color spectrum. Be careful when picking your light!

So you're stuck with tungsten (where RED's blue channel is starved), HMI (probably the best choice, still a bit spiky), Flourescent and LED (both with issues). And... daylight which looks decent if you have the right IR filters on.

Mike P. said:
I've also noticed the "yellow" skin blotches when trying to balance under florescent lighting... And in those cases the subjects were NOT wearing make-up. When something like that happens, you almost have to ride it out and go with stereotypes (like a matrix look for florescent or dragon tattoo look for tungsten) since trying to correct it in post would not be feasible. Lots of needless variables that *seem* to be compensated for with other camera systems.
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Yeah... BTW for tungsten, if you have the light to spare, try putting a CTB filter on your Red. Fun thing to try as it evens out the color channel responses a bit more.

Blair S. Paulsen said:
I agree that RC3 really needs spot on white balance to shine. IIRC when RC3 first landed Jim made it clear that nailing the color temp was the key to getting a purer color palette.
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I agree. I do think that having a digital camera being extremely sensitive to white balance is not necessarily an indication of color accuracy though. It might be an indication of a lot of color matrix stuff happening to compensate for sensor color rendition that results in an unstable solution (but the best possible given the sensor)?

Eg if you look at Lightroom's advanced RAW color profiling, is seems they basically have a little secondary color-correction engine built in. You calibrate it to pull colors in certain directions for tungsten... then do a completely different set of color pulls in daylight. It blends between those settings based on your white balance slider position apparently. So I would imagine that if you had a mythical sensor that worked accurately from the get go in both tungsten and daylight with just basic gain changes, the solution would be more stable? And the less perfect your sensor is, the more trouble it has... unless you want to calibrate separately for every possible illuminant hitting every possible surface spectra?

Basically I agree with everything you said, except just think that this digital stuff is still in its infancy and maybe not 100% right yet.

Bruce Allen
www.boacinema.com
 
Matt Ryan said:
Hey Pablo, Thank you. I got the Kodak but looking for the Fuji now. Redlogfilm is usually where I start, then use an input lut to go to logC.
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Juan Melara has them all in .cube format, fantastic, gracias. I am going to make my own to see how they match..
 
Bob Gundu said:
Wow this has become a very educational thread.
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Agreed - I know skin tones threads are contentious but they're fun when a bunch of smart people generously post their methods of attacking really tricky, subjective problems.

It's fun making filmmaking better :) Personally I love it and it really gets me thinking and inspired.

:cheers2:

BTW I just checked out Bjorn's company's site. Frikkin awesome stuff.

Bruce Allen
www.boacinema.com
 
i noticed that arri's footage cyan is really boosted. Seems to have an effect in bringing out skin tones
 
charles lim yi yong said:
i noticed that arri's footage cyan is really boosted. Seems to have an effect in bringing out skin tones
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+1. I wish that every grading app had not just RGB curves but CMY as well. The math is pretty simple to implement.

I also think that the other major thing left out of grading suites is that you sometimes want to make the mildly-saturated colors more saturated and leave the very saturated colors the same.

You can do this with a key in Resolve but a lot of people seem to never do this. This may help explain why sometimes a 3D LUT seems to do "magic"...

Anyway... does anyone have a favorite non-insanely-expensive app for graphing exactly what all of the 3D LUTs are actually doing? Eg what gets pushed to what...

Bruce Allen
www.boacinema.com
 
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