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Discussion Starter · #1 ·
Hey everyone,

Have another interesting question for you regarding setting contrast.

Conventional wisdom says that we set contrast according to the pluge patterns. I generally aim for above 235 and verify no color push is happening. But on most of my displays this has tended to result in a slight "blip" in gamma around 90 IRE. I've read in the past that this could be a sign of high contrast, but with having set the contrast appropriately and not seeing a change by small changes I discounted it. Now that I have a nice shiny new DVDO TPG, I'm running 10pt grayscales so fast that I decided to continue to drop the contrast until 90IRE leveled out. Sure enough it works out eventually, but its not a small change in contrast. If I set the contrast at 85 with pluge patterns, by the time the 10PT shows a flat 90IRE its closer to 60.

So the question is, whats going on with that...and what would be the correct method to set contrast, by the pluge only, or by using the metered results from the 10pt greyscale?

As usual, thanks for any feedback!

Dan

PS: Meter is a I1Pro2 used with Calman and the DVDO TPG or Tedds Lightspace Disc.
 

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Numerical gamma blips above about 85% are meaningless, it takes a imperceptible difference to generate large swings at those stimulus levels.

You can set contrast using a near white ramp. I believe HCFR has this feature and CalMAN has it in several of it's workflows as well.

I know CalMAN can do this for either 235 or 255. If you have an LCD you should go for 255 for sure, I'd still recommend it with a plasma or projector, but could understand why you might try to maximize light output.
 

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Discussion Starter · #3 ·
Numerical gamma blips above about 85% are meaningless, it takes a imperceptible difference to generate large swings at those stimulus levels.

You can set contrast using a near white ramp. I believe HCFR has this feature and CalMAN has it in several of it's workflows as well.

I know CalMAN can do this for either 235 or 255. If you have an LCD you should go for 255 for sure, I'd still recommend it with a plasma or projector, but could understand why you might try to maximize light output.
Your talking about the dynamic range test, right? I think I usually use that one to check for clipping and set it to "clipping w/ peak white". So is the goal to match the yellow line for contrast, or am I thinking of the wrong thing?

Thanks!
Dan
 

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The ultimate goal is to have red,green, and blue on top of the yellow line.

But since we are doing contrast before we do white point and before we do gamma, all we are concerned about is clipping.

Clipping is where the slope of the changes.

This can happen to all three channels, or one channel. One channel clipping is the most devious.
 

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Discussion Starter · #5 ·
The ultimate goal is to have red,green, and blue on top of the yellow line.

But since we are doing contrast before we do white point and before we do gamma, all we are concerned about is clipping.

Clipping is where the slope of the changes.

This can happen to all three channels, or one channel. One channel clipping is the most devious.
Thanks for the info!

Dan
 
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