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Color Profiles and FCP X (and others)
- Thread starter paulcurtis
- Start date
On the light illusion forum there's a discussion on ICC profiles - from Steve Shaw;
read more here;
http://www.lightillusion.com/forums/index.php?action=vthread&forum=8&topic=28
read more here;
http://www.lightillusion.com/forums/index.php?action=vthread&forum=8&topic=28
paulcurtis
Veteran
The light illusion site is full of interesting information.
It does *also* beg the question and, Dermot you alluded to it, - if you select a different colour space on camera (REC709/Pro/Cinegamma etc,.) are they subsets of REC709 or can PRO produce colours not in the 709 gamut. If that is the case then when they're brought in as REC709 surely we're loosing gamut?
cheers
paul
It does *also* beg the question and, Dermot you alluded to it, - if you select a different colour space on camera (REC709/Pro/Cinegamma etc,.) are they subsets of REC709 or can PRO produce colours not in the 709 gamut. If that is the case then when they're brought in as REC709 surely we're loosing gamut?
cheers
paul
Nirv
Carbonite Member
I can't find any reference to xvYCC (aka x.v.Color) in relation to the FS100 so it's probably safe to assume all colour modes fall in the rec709 gamut.
EDIT:
Scratch that, watching the video negative values may be indicative that we are recording in xvYCC. I need to read more on the subject!! It's all new.
Go to 10 min mark for more on XVYCC.
http://pro.sony.com/bbsc/video/rela...of_broadcast_technology_part_1_hugo_gaggioni/
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i have not seen anything beyond 709 legal on a vectorscope from the FS, but we do work with footage that is much wider gammut (F3/Slog, Epic, Film, Alexa) daily, and it's not a problem atall... only opens up more choices...
If you get a chance, drop your DreamColor into "P3 emulation" and check out all the pretty colors that 709 won't let you see!
d
That was a good primer, thanks for the link..
xvYCC was discribed to me along time ago by a Sony engineer as turning off the clipping in the camera, big selling point of the then new f23
Think i need to test something with the FS now
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Nirv
Carbonite Member
When I put the camera's black level down to -15 I get values from -20 ire up to 109 ire. Does this mean the camera is recording xvYCC or standard REC709 gamut with just an extended gamma range? Maybe the latter?
I have asked Sony's twitter account to clarify but it's a bit hit and miss to get an answer from them.
It seems they've moved their consumer cameras over to xvYCC and some of their HDV cameras as far back as 2009 but absolutely no mention of anything in the FS100 manual.
Once you've seen the Dreamcolor unconstrained it's difficult to go back to 709.
I have asked Sony's twitter account to clarify but it's a bit hit and miss to get an answer from them.
It seems they've moved their consumer cameras over to xvYCC and some of their HDV cameras as far back as 2009 but absolutely no mention of anything in the FS100 manual.
Once you've seen the Dreamcolor unconstrained it's difficult to go back to 709.
Nirv
Carbonite Member
You don't crush the blacks when you change the setup level.
Dropping the black level gives more levels to play with in the blacks during grading especially if you've used the Cinegamma 2 curve. It ensures you've got the most out of your 8 bits.
The low noise sensor means we are not contained like the DSLR people who have to shoot flat to keep their blacks and greys out of the clutches of their horrendous codec and noise. The FS100 has a wide DR and a corresponding huge SNR and many are not exploiting it to its fullest.
Nirv
Carbonite Member
OK, I get it now - thanks
Piotr
Have a look at this image posted by EOSHD, http://www.eoshd.com/wp-content/uploads/2012/04/5d3-vs-fs100-lows.jpg
The 5D3 DSLR is on the left and is a stark reminder why they have to shoot with a flat profile to keep as much detail out of the noise. We don't. Shooting flat also limits you when grading as any major contrast changes just results in posterisation.
When EOSHD posted the image on twitter he asked people to guess which image was 5D3 and which was FS100, quite a few though the 5D3 image was on the right! There is a myth around the 5D.
paulcurtis
Veteran
Don't have time to test today but found this earlier
http://www.sony.net/SonyInfo/technology/technology/theme/xvycc_01.html
As Nirv guessed, it really does look like those -ve values are a result of xyYCC - the cyan side of things should be the way to check this. Now when being being taken into an NLE i wonder how we set up a xyYCC space, i assume if REC709 is assumed the these values get clipped and it generally looks okay. At some time in the past i'm sure i've seen a xyYCC profile in something, just can't remember where
cheers
paul
http://www.sony.net/SonyInfo/technology/technology/theme/xvycc_01.html
As Nirv guessed, it really does look like those -ve values are a result of xyYCC - the cyan side of things should be the way to check this. Now when being being taken into an NLE i wonder how we set up a xyYCC space, i assume if REC709 is assumed the these values get clipped and it generally looks okay. At some time in the past i'm sure i've seen a xyYCC profile in something, just can't remember where
cheers
paul
cpc
Well-known member
Just a clarification:
Shooting flat profiles doesn't bring detail up out of the noise. If anything, it brings both detail and noise up.
Nirv
Carbonite Member
Care to explain please?
My understanding is, the signal to noise ratio is reduced (less effective bits to play with) when they use a flat profile as they're trying to lift the usable tonal range out of the area codec mangles. The Codec in the DSLRs is relatively unsophisticated and macro blocks in the black region which is what I though they were trying to avoid with the flatter profiles?
Where does the noise come from? Lifting the blacks? And how does detail come up too?
If you could spare the time to explain I'd be very grateful, cheers.
moldcad
Veteran
Nirv and cpc - I guess you are both right. As I understand what Nirv syas, with the FS100 we can afford shooting with negative black levels, because - unlike HDSLRs - the low noise and superior FS100 codec will allow to push it up above 0 IRE in post, without revealing excessive noise (which simply isn't there - well, at least compared to say the 5D). Should the noise be higher, pushing things up in post would reveal it as well - which is what cps is saying...
Or am I misinterpreting things?
Or am I misinterpreting things?
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MattDavis
Well-known member
Ah, the campanology of technological epiphany! Bells are ringing throughout the synapses of many folk gathered here.
So, 'of course' we finally get to use the SuperWhite settings from 100% to 109% that CineGammas gave us. What I hadn't twigged until those marvellous presentations by Hugo Gaggioni et al, was that the 0-16 levels were up for grabs too. That makes sense of what I've been seeing in the WFMs of FCPX - detail dipping below the 0.3v line which is still valid detail, AND it makes sense (in my fluff-filled brain) of Andy Shipside's tests at long last, because his Extended Dynamic Range seemed to sacrifice so much to the 'cut off below the knees and above the neck' zone. He's assumed that we'd know that those 'there be dragons' zones are still valid in the digital world, and I've taken on board the highlight end, but doggedly stuck to protecting blacks (hence the drift to higher black settings in FS100 Picture Profles) to ensure we don't get the 'black clip' one can get with using Negative Gain on an EX1, apropos of the whole picture profile movement.
Or alternatively, I've got the wrong end of a completely random stick. Which has happened before.
Which begs the question - if using the 0-16 and 235-255 ends of our brightness range effectively - should legalisation (to Rec709 presumably) be a process of squishing, or decapitation? I fear the latter is the rule at the moment.
So, 'of course' we finally get to use the SuperWhite settings from 100% to 109% that CineGammas gave us. What I hadn't twigged until those marvellous presentations by Hugo Gaggioni et al, was that the 0-16 levels were up for grabs too. That makes sense of what I've been seeing in the WFMs of FCPX - detail dipping below the 0.3v line which is still valid detail, AND it makes sense (in my fluff-filled brain) of Andy Shipside's tests at long last, because his Extended Dynamic Range seemed to sacrifice so much to the 'cut off below the knees and above the neck' zone. He's assumed that we'd know that those 'there be dragons' zones are still valid in the digital world, and I've taken on board the highlight end, but doggedly stuck to protecting blacks (hence the drift to higher black settings in FS100 Picture Profles) to ensure we don't get the 'black clip' one can get with using Negative Gain on an EX1, apropos of the whole picture profile movement.
Or alternatively, I've got the wrong end of a completely random stick. Which has happened before.
Which begs the question - if using the 0-16 and 235-255 ends of our brightness range effectively - should legalisation (to Rec709 presumably) be a process of squishing, or decapitation? I fear the latter is the rule at the moment.
Nirv
Carbonite Member
Yep, if you hand the footage off to an editor who isn't going to grade the footage back into rec709 legal territory and just relies on a crude legaliser it's a decapitation and severing of the legs just below the knees job. If you are shooting to grade then you can bring up the blacks all you want.
I've only had the camera couple of weeks and have been trying to get a handle on how to best set it up. In the tests I have found almost impossible to clip black detail, you have to go to herculean efforts to under expose. The LCD has to literally be filled with black for you to know that black detail is clipped even with a black setting at -15. There is no reason to clip a highlight as there's plenty of DR to save the highlight and not clip the black either. The scene will look shockingly under exposed on the LCD but that's a failing of the LCD set not the camera. Try and ignore what the LCD is showing (use the force) and bring up the blacks in post.
We're getting to the point where Sony are seriously going to have to consider a viewer LUT for the LCD when the cinegamma curves are used so it's easier to expose.
IMHO, the FS100 is a gem of a camera and I can't understand why there is still a market for DSLRs...
paulcurtis
Veteran
It's a definite there be dragon territory. I'm trying to get some tests done now. Hopefully get some time to post later or tomorrow.
Here are some questions and observations so far
1) We don't know if it's outputting xvYCC, the negatives in the output suggest it might be, but that could just be for luminance. For the xvColour to work the NLE would need to understand negative in the chroma channels and we have no idea whether it does. (the extra colour comes from negatives there, not the Y) If i could find an object that i knew was out of gamut then i suppose we could test empirically. Sadly i'm a few thousand miles away from any of those aqua seas they talk about in the marketing blurb. Looking at the weather outside i think the real world is in 709 gamut right now. I've not seen any mention anywhere yet of this support across any NLE. Also if it did support it, i'd expect it to be noted in the docs! Like for other cameras.
2) I'm not convinced about the xvYCC side of things, and if it is doing this then what's coming out of the HDMI. Because AFAIK it's RGB, not YUV and correct me if i'm wrong but the xvYCC space is greater than the sRGB, so a 24 bit RGB signal might not be able to represent a full range. This puts us into an interesting situation that means the AVCHD YUV could be a greater gamut than the uncompressed HDMI. I've just done some comparisons between uncompressed and AVCHD with negative black levels so i will dredge through that later.
3) I've been using a small HD with false colour to tell when the signal hits 0, i don't know yet whether that's correct and also that's on the HDMI output. I've not really fathomed out yet what black level is really doing.
4) An interesting side though is *if* the HDMI is slightly different colour to the AVCHD then i wonder whether the two can be combined to increase the colour depth of the file. Internally the processing is 12 or 14 or whatever. If the HDMI comes through a different path perhaps the colours are slightly different, enough to fill in some gaps in the 8bit. This is strictly fantasy territory for now mind.
Nirv, my basic tests so far with black levels (assuming that smallHD false colour is accurate) shows that i can quite easily clip black at -15, not so easy at 0 and impossible at +15. This is cinegamma 1.
so onwards and upwards, or rather downwards into the depths of black...
cheers
Paul
Here are some questions and observations so far
1) We don't know if it's outputting xvYCC, the negatives in the output suggest it might be, but that could just be for luminance. For the xvColour to work the NLE would need to understand negative in the chroma channels and we have no idea whether it does. (the extra colour comes from negatives there, not the Y) If i could find an object that i knew was out of gamut then i suppose we could test empirically. Sadly i'm a few thousand miles away from any of those aqua seas they talk about in the marketing blurb. Looking at the weather outside i think the real world is in 709 gamut right now. I've not seen any mention anywhere yet of this support across any NLE. Also if it did support it, i'd expect it to be noted in the docs! Like for other cameras.
2) I'm not convinced about the xvYCC side of things, and if it is doing this then what's coming out of the HDMI. Because AFAIK it's RGB, not YUV and correct me if i'm wrong but the xvYCC space is greater than the sRGB, so a 24 bit RGB signal might not be able to represent a full range. This puts us into an interesting situation that means the AVCHD YUV could be a greater gamut than the uncompressed HDMI. I've just done some comparisons between uncompressed and AVCHD with negative black levels so i will dredge through that later.
3) I've been using a small HD with false colour to tell when the signal hits 0, i don't know yet whether that's correct and also that's on the HDMI output. I've not really fathomed out yet what black level is really doing.
4) An interesting side though is *if* the HDMI is slightly different colour to the AVCHD then i wonder whether the two can be combined to increase the colour depth of the file. Internally the processing is 12 or 14 or whatever. If the HDMI comes through a different path perhaps the colours are slightly different, enough to fill in some gaps in the 8bit. This is strictly fantasy territory for now mind.
Nirv, my basic tests so far with black levels (assuming that smallHD false colour is accurate) shows that i can quite easily clip black at -15, not so easy at 0 and impossible at +15. This is cinegamma 1.
so onwards and upwards, or rather downwards into the depths of black...
cheers
Paul