Picture Profile Recipes

[Sebastien Thomas]

Originally Posted by Randy Strome

Very interesting guys, and thanks for the post.

I have to play village idiot again and admit to not understanding the fundamentals here. If I have it correctly, these are representations of what is happening to a linear 0-255 gradient when each of the gamma setings is applied. Is that correct?

If so, in (for example Cine 1) why is every value from 207-255 being mapped to a flat 207?

I thought I understood your wire analogy, but did not imagine the wire being bent flat at both ends. I thought we were talking about a smooth rolloff as is depicted by the curves in the user manual, but certainly not a long flat spot from 207 on. Well...I can not understand what value there would be to that, but then again, I have always found pre-processing curves to be a mental puzzle.

As you can see, I need to be set straight. HHHEEELLLPPPP!

Of course you're right. The Gain on the camera was +3db, which push everything to white.
I will update the article with 0 gain pictures. Except that, the theory is true.

[Randy Strome]

This all raises another question which has been nagging at me. It seems like there would be a lot of value to some curves with the overall range reduced similarly to the Cine curves, but much more linear in nature (especially less compression of the whites). In a lot of cases (see the exmaple titled watermen I posted here http://dvinfo.net/conf/showthread.ph...498#post843498) I am seeing situations where I need to protect my whites, and thus need dynamic limitation (for lack of a better term), and have been careful not to overexpose any channel over 230 for safety (and potential user error), but the whites still appear blocked up as in overexposure, due to such a broad range of whites being compressed to such a narrow range. Also, we are pushing the blacks more than might be needed (I am typically backing of black gamma in post). Has anyone taken a crack at a PP (or group of PP's) like this?

[Michael H. Stevens]

Originally Posted by Sebastien Thomas

Of course you're right. The Gain on the camera was +3db, which push everything to white.
I will update the article with 0 gain pictures. Except that, the theory is true.

I suggest gain of -3dB which is the "real" zero.

[Michael H. Stevens]

Originally Posted by Randy Strome

This all raises another question which has been nagging at me. It seems like there would be a lot of value to some curves with the overall range reduced similarly to the Cine curves, but much more linear in nature (especially less compression of the whites). In a lot of cases (see the exmaple titled watermen I posted here http://dvinfo.net/conf/showthread.ph...498#post843498) I am seeing situations where I need to protect my whites, and thus need dynamic limitation (for lack of a better term), and have been careful not to overexpose any channel over 230 for safety (and potential user error), but the whites still appear blocked up as in overexposure, due to such a broad range of whites being compressed to such a narrow range. Also, we are pushing the blacks more than might be needed (I am typically backing of black gamma in post). Has anyone taken a crack at a PP (or group of PP's) like this?

I think you will find most are backing of blacks in post or in the camera with negative settings for master black and black gamma. To get a good spread of whites use the histogram and push exposure a bit. I started off preaching the wisdom of under exposing and Bill almost sh*t down my neck but with experimentation I think he is half right. I say only half because from my experiments when the 100 zebra shows up (Bill's point) you are still a stop or two underexposed. Try going further for which you will need watch the histogram so as to stop pushing it short of blowing.

[Randy Strome]

Originally Posted by Michael H. Stevens

I think you will find most are backing of blacks in post or in the camera with negative settings for master black and black gamma. To get a good spread of whites use the histogram and push exposure a bit. I started off preaching the wisdom of under exposing and Bill almost sh*t down my neck but with experimentation I think he is half right. I say only half because from my experiments when the 100 zebra shows up (Bill's point) you are still a stop or two underexposed. Try going further for which you will need watch the histogram so as to stop pushing it short of blowing.

Thanks Michael,
So many confusing terms.

Negative settings for Master black sets the black point below zero. I think that may have been the wrong way to start for my type of shooting. It did deepen the lower quartile darks that I was concerned with, but with the additional consequence of driving all near blacks through the floor. We can only "Gray those back up" in post, but with noise of course. I am envisioning a curve with black level at Zero and black gamma reduced. Whites starting at ranges from 100 to 80 with a lower and less drastic knee on each.

Your last point is the tricky one, because we are all right, kind of.

If the curve was more linear, pushing to the right would act more like RAW. The test above (although accidentally) shows the current problem with that with our current curves. One stop over, and due to the nature of the curve, everything from 255 to 207 gets mapped to a single value. Even in a case of proper exposure they are getting mapped to such a narrow and similar range, that in many cases they will "read" as blocked up or blown.

[Randy Strome]

I did a bit of playing around with SAW in an attempt to better familiarize myself with what our camera is doing. I should note, that this is not any kind of negative critque of the camera, just one user trying to figure out some best practices.

Regardless of the camera's gain setting, a flat spot exists in each of the available gamma settings, indicating to me that all values above a specified point are being mapped to a single value. Knee (on or off) changes the curves transition into this flat point, but does not alter it.

Why would it be valuable to map (for instance) any incoming value of over 200 to an output value of 200?

Apologies, I feel like I am missing something obvious, but what is eluding me.

[Michael H. Stevens]

Ok I'm out of this thread. I think I've got all I need now and I know where I was going wrong.

You can not set a few PP and use them only - you must adjust some paint settings like master black on every shot. I can eliminate any need to manipulate the blacks in post. I think the CINE gammas despite the criticism of the white range handle the white roll offs fine as long as you use CINE1 for very bright scenes and keep Cine4 for the gentler light.

My remaining decision not yet made is HiSat or Cinema. HiSat (compared to Cinema) has a yellow ting to me but I have not yet compared with Bill's color shifts

[Sebastien Thomas]

Originally Posted by Randy Strome

I did a bit of playing around with SAW in an attempt to better familiarize myself with what our camera is doing. I should note, that this is not any kind of negative critque of the camera, just one user trying to figure out some best practices.

Regardless of the camera's gain setting, a flat spot exists in each of the available gamma settings, indicating to me that all values above a specified point are being mapped to a single value. Knee (on or off) changes the curves transition into this flat point, but does not alter it.

Why would it be valuable to map (for instance) any incoming value of over 200 to an output value of 200?

Apologies, I feel like I am missing something obvious, but what is eluding me.

Maybe someone should do the same test with the SDI output... I will if I can get a hand on an oscillo.
Whatever, you will ever have differences between what you see (and what you may get in 10 bits SDI) and what you record, 8bits + codec.

[Randy Strome]

Originally Posted by Sebastien Thomas

Maybe someone should do the same test with the SDI output... I will if I can get a hand on an oscillo.
Whatever, you will ever have differences between what you see (and what you may get in 10 bits SDI) and what you record, 8bits + codec.

I am looking at the output directly from the SDI. The mini monitor I am using has a waveform so I am able to live view the curve as changes are applied.

The "flat spot" is present in all PP's and is very relevant to me, because it explains a lot about how whites are being handled.

I owe you guys a big thanks, because I had no idea that the SAW function was present and you are absolutely correct that it is imperative for adjusting these PP's with any accuracy.

[Adam Simpson]

I have followed this thread for a while. I have used and loved the presets developed over time. Thanks for sharing all the work.

I am curious if anyone has formulated a true color preset with a Letus and EX1. I realize this is somewhat imprecise as it depends on the lens used, but it would still be helpful. I know Phillip is now shooting with both a Letus EX1 and a "naked" EX1. I am going to be doing the same. I have 2 EX1's, one with a Letus one without. I use primarily my Zeiss 85mm 1.4 ZF lens. I would love to find a preset that matches the base EX1. Phillip, do you have any recommendations? I will have a break in productions over the next few weeks, so I will try to do some work on my own, but would appreciate any advice.

Thanks,

Adam Simpson

[Paul Kellett]

Quick question regarding crushing or stretching.
If my black is set at 0 and i go down to minus whatever,say -10, is that crushing or stretching ?

Thanks.
Paul.

[Piotr Wozniacki]

Originally Posted by Paul Kellett

Quick question regarding crushing or stretching.
If my black is set at 0 and i go down to minus whatever,say -10, is that crushing or stretching ?

Thanks.
Paul.

You are crushing (compressing), Paul.

[Paul Kellett]

Thanks Piotr.
That's what i thought.

[Bill Ravens]

FWIW...

Studying the SAW display in HDRack's waveform monitor, it is apparent to me that a gain setting of -3dB is NOT equivalent to the "real" 0. A GAIN setting of -3dB limits the superwhite IRE to a value of ~90 IRE. Only the 0dB GAIN with 3200K for a white balance yields a neutral, full scale curve. Along with this, I will also note that my previous BLACK settings seem to be causing noise in the shadows, indicating the shadows are being crushed. With data from the SAW that Randy provided, the min setting for BLACK I now recommend is -3 or -4.

[Piotr Wozniacki]

Originally Posted by Bill Ravens

FWIW...

Studying the SAW display in HDRack's waveform monitor, it is apparent to me that a gain setting of -3dB is NOT equivalent to the "real" 0. A GAIN setting of -3dB limits the superwhite IRE to a value of ~90 IRE.

Thanks Bill - now I understand why I'm getting higher Vegas scopes reading for my V1E stuff, than for the EX1 when at -3dB...