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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 :)

Interpreting the histogram

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Irri

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I have a few questions about the histogram on the camera’s monitor. Sorry if this has been covered before.

What does it monitor? Linear light, the REC709 monitor signal we are seeing, or something else?

How is it divided up?
Say it was monitoring linear light:
Is it sliced into 11 equaly sized (in terms of left to right) stops?
Is more like 12 bits across with the rightmost half being 2048 indices, representing the last stop.

Sorry if this badly explained; I’ve just come off a long shoot.
 
Great question! I believe this was discussed a while back. At the time the general consensus was that the histogram was based on Rec 709 and not linear, but this was back during earlier builds... Perhaps build 16 makes this more clear. I personally think basing the Histogram off the linear light would make the most sense.
 
What would be the point to measure LCD content if you are recording RAW
It is like measuring exposure of the view finder content in DSLR camera, cam on can`t be...
 
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I think there was a mention somewhere around build 14 saying it was based on something log.

Another question I would like add to add is: what exactly does the line at the right that rises sometimes mean? I find it a little confusing as it appears when none of the channel clipping traffic lights are lit.
 
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Hmm, just had a thought. It can't be RAW linear light because it changes with the ISO setting.
 
Andrew said:
What would be the point to measure LCD content if you are recording RAW
It is like measuring exposure of the view finder content in DSLR camera, cam on can`t be...
Click to expand...

?

What is this in response to? Were talking about monitoring the signal being recorded.
 
Exactly, signal being recorded not displayed.
I don't think rev 15 is displaying histograms or traffic lights based on the 709.
We need to know the state of the RAW being recorded not the state of the signal being fed to the LCD screen.
I remember that there were some posts complaining about 709 color space on the LCD display
but I think it is long gone.
 
Andrew said:
Exactly, signal being recorded not displayed.
I don't think rev 15 is displaying histograms or traffic lights based on the 709.
Click to expand...

I'm pretty sure it is. I'm not aware of any update that changed anything in this regard.

You're right, it doesn't make sense. Well... the way I understood it was it was easier to program. It makes sense from that standpoint. The fact that everything changes when ISO is changed let's us know we're not looking at raw sensor exposure data.

I think this very well may change in build 16 though as Jim has many times mentioned setting exposure will become easier.
 
This is only my second post and I'm trying to keep up with the info being tossed around as much as the next guy. But a lot of people on this message board kind of tick me off by continually comparing the RED to DSLRs, as if we've all been shooting on them for the last 10 years and are completely familiar with DSLRs. I'd like to see the questions explained in a way that assumes that the person asking the question isn't familiar with similar technology... otherwise, why would he/she be asking?
 
Good question, but one that shouldn't have to be asked if Red would provide spec sheets with their products. This "everything is subject to change" line only works to a point. Until Red can tell us what we're getting for our $1,700 to $2,500, I'm going with Leader waveform monitor products. Lot more expensive, but at least I know what I'm getting.

Tail Ends
 
Tail Ends said:
I'm going with Leader waveform monitor products. Lot more expensive, but at least I know what I'm getting.
Click to expand...

No you won't. You are recording RAW. Those waveforms aren't designed for use with RAW cameras. Sure, you can analyze the monitor output, but thats not whats being recorded.
 
That is why I Adobe OnLocation, has set of monitors and useful instruments.

I was using it to pick the adjustment color filters.
But now I am not sure if SDI monitoring output is RAW or not?
I guess it is, otherwise my adjustments wouldn't click so nicely.
Anybody has good idea if monitoring via SDI in rel 15 is actually monitoring RAW?
 
Histogram etc

Histogram etc

With Build 15 and all previous versions the Histogram is showing you REC 709 profiled data. Same for the Waveform monitor, false color and Zebras.

The bar that comes up at the right edge of the histogram shows you when the image is starting to clip in REC 709 space.

If you are shooting ISO 320 or above, you can NOT clip the RAW data if you just back off from when the "traffic light" sensor clip indicators come on.

The HD-SDI and HDMI outputs on Build 15 and all previous versions are 10 bit 4:2:2 REC 709
 
So sensor clip indicator is actually REC 709 clip indicator, correct?
or
It is real sensor clip indicator?
Looks like we are back to the drawing board............or I just wait for the 16-th?
 
Andrew said:
So sensor clip indicator is actually REC 709 clip indicator, correct?
Click to expand...

It's REC 709, but there probably is some method to the madness here. In REC 709 at ISO 320 the sensor is actually getting more data than you are being told, so it's protecting you from overexposing.
 
But isn't protecting you by 0.4 stops, of the last stop which is (2046*0.4=819) out of our 4096?

I noticed today that the traffic lights don't seem to work below 200 ISO.
 
RAW Histogram setting?

RAW Histogram setting?

Stuart English said:
With Build 15 and all previous versions the Histogram is showing you REC 709 profiled data. Same for the Waveform monitor, false color and Zebras.

The bar that comes up at the right edge of the histogram shows you when the image is starting to clip in REC 709 space.

If you are shooting ISO 320 or above, you can NOT clip the RAW data if you just back off from when the "traffic light" sensor clip indicators come on.

The HD-SDI and HDMI outputs on Build 15 and all previous versions are 10 bit 4:2:2 REC 709
Click to expand...


Stuart,

I'm wondering if there is currently a way (or will be a way in build 16) to view the RAW Histogram. I haven't found it in the manual if there is. That seems to be the holy grail in terms of ultimately determining your exposure. From what you said above I understand that the histogram is affected by ISO settings in the camera and is in REC 709 space. Is there any way in camera to see that RAW histogram info or only after the material is shot, in RED Alert! or REDCine?
Will Build 16 have a RAW Histogram function? Can you attach it to a user button for quick reference?

Thanks,
Brian
 
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