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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 :)

REC709 Output and the need for 4K Monitors

tillHavis said:
OK the recent Rodney Charters post has raised a few interesting issues to discuss. This is great and will only lead to a better Red camera and monitoring solution.
Airing these issues helps make a better camera; and at the end of the day if these are real world issues and concerns when working with current monitors they should be discussed.
So Keep it nice !!!

P.S. Personally the one thing I got from the recent discussion was the need to have a better and accurate monitoring solution for RED footage.
4K footage needs better a better monitor than the current crop of displays to do it justice.

To get the ball rolling heres what Alexander said
Click to expand...

I think Rodney was looking at a log output vs rec709ish on red.
Rec709 is supposed to show a higher contrast image while log is flat.
 
Yikes! Someone takes what I say here seriously?

Anyway, I've never been really happy with the monitoring from the RED One.

It has some cool tools, but not a standard REC709 output. To be clear, its the output on the RED itself that I think is the issue- not the monitors people are attaching.

What I need most of the time is "standard" REC709 output to at least one monitor for clients/directors. A best estimate of how the metadata I've set in camera will show up if rendered without further adjustment to a REC709 format piped out SDI so that most monitors will show what the "finished" image will look like.

On most shoots people understand about color correction and such, but they are increasingly used to seeing a REC709 feed from an ENG camera as the basis for deciding whether or not they can push the existing image one way or another.

To be completely fair to RED, I am best served with the weird false color images that help me think about the REDCODE negative I am creating. I am quite sure that for a lot of users this works out just fine.

I think this will really be a non-issue for Epic & Scarlet. I just re-read the November 30th announcement, and I noticed that #16 was "Independent LUT's on Monitor Outputs."

Now I take that to mean that every monitor path will be able to load a distinct LUT. So, I can have one set of looks on the on camera EVF another on the on camera monitor and yet another look on the client/director monitor over SDI (or HDMI I suppose)

I'd urge RED to make a REC709 LUT available in the cameras by default, so its easy to set the camera up for use with monitors from various sources. This seems obvious, but its the sort of thing that could easily get lost in the shuffle. I could make my own REC709 LUT... but I'm sure RED can do a better (i.e. more standards compliant) job than I can, or at least do so more easily.

The harder part is to get some sort of REC709 look back into the firmware for RED One. Build 17 or so had such a setting... but it didn't look very good. My feeling is that it needed to be improved, not eliminated.

Again, the current tool set is great when I am shooting something where I get to be the final arbiter of the image. That's fairly rare nowadays though. All sorts of stake holders like to put in their two cents. It isn't like the "old film days" where the video tap was clearly unreliable and everyone just had to "trust" the DP. (Until dailies came back anyway)
 
Alexander Ibrahim said:
RED needs a real top notch REC709 HD-SDI signal out their HD-SDI ports.

That's a full 720p 10 bit 4:2:2 REC 709 image, one that can be recorded if the user wishes and used for dailies or offline editing if desired- or heck even 720p delivery if the user desires.
Click to expand...

I am not entirely sure that RED One hardware can deliver this- but this is what I want.

In thinking about it, the camera would probably have to deliver at 1/2 debayer in realtime in order to make deliverable quality output. I think what it does deliver is 1/4 or 1/8 debayer.

That may take so much redesign that you may as well just order a Scarlet.

If that is the case, then I'd ask that RED do as much as practical to make a REC709 output option that is easy and conforms to what monitors expect to see from cameras.

Why might this have been overlooked? Well, on high end productions its common to have monitors that can load LUTs, but most production monitors can't do that.

If I have a Cinetal on set I can just load a LUT and make my odd duck camera look great and be on my way. If I have a Panasonic 1710 or a Sony LMD series that isn't an option.
 
Monitoring settings

Monitoring settings

Alexander you are assuming way too much about the "limits" of the camera's monitoring implementation.

As Mitch hinted you do NOT want a standard REC709 gamma output to the monitoring - that directly leads to a "clippy" response in the highlights.

What you would ideally want is an internal LUT (LOOK file) to modify the response - which is exactly what RED ONE (and EPIC) already have.

If that LUT (LOOK file) is set up appropriately, then the camera video output, displayed on a REC709 calibrated monitor, will look just fine...
 
P.S. Personally the one thing I got from the recent discussion was the need to have a better and accurate monitoring solution for RED footage.
4K footage needs a better monitor than the current crop of displays to do it justice.
A calibrated Red 2- 4K Monitor would also eliminate this type of quick to judge reaction caused by Monitors/LUt's etc.. not being properly set.
If a single video showing some shaky footage can cause such a stir; then one video with an optimzsed RED 2-4K monitor would eliminate the need to constantly refer
and defend what we all know is a great camera.
Click to expand...

I agree !
 
Stuart English said:
Alexander you are assuming way too much about the "limits" of the camera's monitoring implementation.

As Mitch hinted you do NOT want a standard REC709 gamma output to the monitoring - that directly leads to a "clippy" response in the highlights.

What you would ideally want is an internal LUT (LOOK file) to modify the response - which is exactly what RED ONE (and EPIC) already have.

If that LUT (LOOK file) is set up appropriately, then the camera video output, displayed on a REC709 calibrated monitor, will look just fine...
Click to expand...

Would RED consider releasing/providing a fully compliant and tested REC709 look file? I'm sure you have them for internal testing. Many people would take advantage of it.
 
REC 709.

REC 709.

Would RED consider releasing/providing a fully compliant and tested REC709 look file? I'm sure you have them for internal testing. Many people would take advantage of it.
Click to expand...

What do you mean by that Jay ?

And what do you expect that would do for you?
 
Well it would allow people to apply a look to the monitoring that would map the output to the available REC709 on most monitors. That way once the monitor is calibrated you can be reasonably happy that the monitoring will be accurate.
 
A LUT calibrated with a waveform monitor and vectorscope off of the HDSDI output makes sense if you are shooting for HD REC709 finish or want to record the HDSDI output directly for video finish.
If you use this as on set reference to a monitor, then you would light and expose for the optimum REC709 image.
 
REC 709.

REC 709.

Well let me first say that the HD-SDI output of the camera already is REC709 compatible. After that, the discussion, by definition, gets less clear.

So, to understand your point better : can you explain what you mean by "calibrated"?
 
Try shooting your new Redcam color and grayscale reference chart and run the output to a waveform monitor.
I think the main goal would be with a reference 2.2 gamma setting to get the IRE exposure values within REC709 legal limits, 7.5 ire black and 90 IRE white for the grayscale step segment of the chart. This would come close to simulating what you would get out of a broadcast camera HDSDI output. Broadcast cameras use knee and toe compression to stay within this value range without clipping though. The dynamic range is effectively about 8-9 stops max.
 
Stuart English said:
If that LUT (LOOK file) is set up appropriately, then the camera video output, displayed on a REC709 calibrated monitor, will look just fine...
Click to expand...

Could you e-mail me an example of your LUT which is set up properly?

David
 
David Collard said:
7.5 ire is irrelevant with some digital broadcasters. Japan comes to mind at 0 ire, though I may stand corrected.
Click to expand...

If one is shooting a printed chip chart, the black is generally 3% reflectance and white is generally around 90% give or take a couple of percent.
There is not a hard line here for sure.
For film transfers using their 3 chip reference chart with 90% white, 18% gray and 3% black, Kodak recommends 80 ire, 50 ire, and 20 ire for the to leave head and foot room to accomodate the larger dynamic range of film.

8 bit HDSDI RGB digital reference values for REC709 are 16:16:16 for 0 ire, 128:128:128 for 50 ire and 235:235:235 for 100 ire.
 
Stuart English said:
Alexander you are assuming way too much about the "limits" of the camera's monitoring implementation.

As Mitch hinted you do NOT want a standard REC709 gamma output to the monitoring - that directly leads to a "clippy" response in the highlights.

What you would ideally want is an internal LUT (LOOK file) to modify the response - which is exactly what RED ONE (and EPIC) already have.

If that LUT (LOOK file) is set up appropriately, then the camera video output, displayed on a REC709 calibrated monitor, will look just fine...
Click to expand...

Well Stuart, I'd like to stop guessing about RED One's monitoring path and LUT files. Seriously.

How exactly does the RED One monitoring path work?

How do I set up LOOK files to make an output that matches a given profile? I have REC709 in mind right now, but a D-Cine profile might be nice.

Did I miss a technical note that explains all this? Is there a posting somewhere here on REDUser I haven't seen?

Quote:
Would RED consider releasing/providing a fully compliant and tested REC709 look file? I'm sure you have them for internal testing. Many people would take advantage of it.

What do you mean by that Jay ?

And what do you expect that would do for you?
Click to expand...

What I expect the REC 709 output to do for me is:

Give an accurate indication of when the camera is clipping, or when the shadows are no longer resolving detail.

Give me a reasonably reliable estimation of the colors being recorded.

Generally give me an image I don't have to spend twenty minutes explaining to every producer and director I work with who is new to RED and/or film. Ideally it will also allow me to minimize arguments of the general type that goes:

"You are clipping the image."

"No I'm not"

"Yes you are! I can see the monitor myself. Stop down."

"The monitor can't represent what the camera can record. If I stop down it will be too dark."

etc etc ad infinitum. I believe I am still on some of those sets arguing with people, I always have been and always will be.

So... I want a LUT that displays the RED image with a gamma curve that will achieve these goals on a monitor that expects a REC 709 standard gamma from the camera. Importantly the LUT will make sure that a production monitor expecting REC709 will represent the sensor's clip as clipping... and not clip appreciably earlier. Secondarily, the LUT will make sure that there is some detail visible until the camera is rendering flat blacks. If we must sacrifice some shadow detail to preserve highlight detail, that is acceptable.


In combination the first two should allow me to make reasonable use of a hardware waveform via SDI as a guideline for exposure.

Third, color should be the nearest REC709 approximation of what the camera sees. This last bit is much more subjective, but we can probably agree that the white point in metadata should be displayed as white on the REC709 monitor.

That is probably not the same curve that a REC709 video camera will employ internally as it moves video into the monitoring path- because the RED is not really a REC709 camera.

What I don't expect is just as important.

I don't expect a more accurate REC709 output to provide definitive exposure guidance- I still want and expect to use RED's other displays and tools like a light meter.

I don't expect to have every scrap of detail and subtle shade of color jammed into REC709. For one, resolution. Two it is a 4:2:2 output. (I thought you could gang them up for dual link HD-SDI, but I haven't seen anyone do that. Is it possible?) I also expect some information is just out of gamut.
 
Alexander Ibrahim said:
"Yes you are! I can see the monitor myself. Stop down."

"The monitor can't represent what the camera can record. If I stop down it will be too dark."

etc etc ad infinitum. I believe I am still on some of those sets arguing with people, I always have been and always will be.
Click to expand...

Huh. I just had the opposite thing going on. The on camera LCD was much brighter than the HD-SDI monitor. The monitor may very well have been messed up.

Normally I DP and operate. I set exposure using all the in camera tools. This time I was an assistant and was monitoring exposure via our tiny video village. I really wanted all my exposure tools there. EPIC with custom output LUTS and full remote control would have been perfect.

In this case the DP used the HD-SDI monitor's histogram most of the time. He just wasn't that good with RED's built in stuff and didn't really seem to want to learn it on the fly - so what are ya gonna do? He was going to do what he's been doing with other cameras. Period. In the end I think he mostly got it about right, but I'm worried we blew out some exteriors more than we should have. I came running to camera a number of times to verify and change exposure when I felt things were wrong.

Clearly this stuff isn't "easy" yet.
 
Alexander Ibrahim said:
I don't expect a more accurate REC709 output to provide definitive exposure guidance- I still want and expect to use RED's other displays and tools like a light meter.

I don't expect to have every scrap of detail and subtle shade of color jammed into REC709. For one, resolution. Two it is a 4:2:2 output. (I thought you could gang them up for dual link HD-SDI, but I haven't seen anyone do that. Is it possible?) I also expect some information is just out of gamut.
Click to expand...


Amen.

I raised a similar point when they introduced build 30 here.

I've been grieving for 709 and monitoring ever since.

jb
 
David Collard said:
7.5 ire is irrelevant with some digital broadcasters. Japan comes to mind at 0 ire, though I may stand corrected.
Click to expand...
As far as I know, every HD master I've ever worked on was delivered with 0 blacks, and that's on about 20 different network series and more feature films than I can remember, all in REC709. But that's more about color space.

Only when the images are downconverted to SD (REC 601) do we introduce 7.5 ire setup. The look changes slightly, but it's not drastic if the monitor is adjusted correctly. We haven't even looked at standard def in mastering for the last decade, pretty much. We only color-correct for 2K or HD, then the downconverted tapes go to QC before delivery. Japan has sometimes used 0 blacks in the past for NTSC videotapes in the 1990s, but it's really no longer a consideration in 2010.

The whole issue of monitoring on the set is an enormous headache. I don't think enough people consider that unless and until you calibrate your monitors on the set and make them identical to those in the edit bay, the viewing room, and in the final color correction room, what you look at could be in outer space in terms of look. All the LUTs in the world won't make it right if the on-set display isn't calibrated.
 
Monitor Set Up - Grey Scale

Monitor Set Up - Grey Scale

All the LUTs in the world won't make it right if the on-set display isn't calibrated.
Click to expand...

Very true, so on the RED ONE we provide a Grey Scale to allow you to check if your monitor is resolving blacks and whites correctly.

Go to SYSTEM / SETUP / PREFERENCES / DISPLAY - GREY SCALE. Check to Enable.

This places an 11 band linear grey scale graphic overlay into the right edge of LOOK AROUND. This shows up in HD-SDI as well as LCD / EVF.

Verify that your monitor can reproduce all 11 steps - if it can't do that then the monitor is either clipping the highlights or shadows or both.

i.e. it's not showing you what the sensor is capturing... so then you would need to take some secondary action to solve that.


Of course if you are checking the camera's EXPOSURE false color overlay, such a system problem is moot as EXPOSURE is 100% accurate.
 
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