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Discussion Starter · #1 ·
I own a Sanyo PLV-Z2000, which does not offer high/low gains on colors. It has RGB color controls and RGB custom gamma controls. When calibrating grayscale, I should have the RGB colors set where I want them before I start. What IRE should I use as the basis for setting my RGB color controls? Is there a standard? Do I choose the most problematic part of the scale? any advice?

Thanks - Steve
 

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Greetings


Start in the middle ... and work down. We are more forgiving of errors on the bright end.


regards
 

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From my experience I generally use 50 or 60 ire as a starting point. Then I take a full greyscale reading. Then if everything is good except 90 to 100 ire then you compromise some on the lower to bring the upper to an acceptable level. This could happen vice versa and as Michael said, the lower end is more important.


Daniel
 

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I fully agree that error is more visible at the low end (with the exception of abruptly discolored bright whites due to clipping), which brings me to a great calibration mystery... Why are DeltaE errors weighted to the high end, when they are supposed to approximate how we see? If I have a +10% green reading at 20% stim it may only give a DeltaE of 1, but if I have the same reading at 100% stim it may give a dE of 3? These numbers aren't exact, BTW, I just made them up for illustrative purposes.
 

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Discussion Starter · #5 ·
Gentlemen, thanks for the responses. I just bought a new blu-ray player, so I'll be re-calibrating this weekend. I'll start with 50IRE.
 

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Quote:
Originally Posted by Chad B /forum/post/15571999


I fully agree that error is more visible at the low end (with the exception of abruptly discolored bright whites due to clipping), which brings me to a great calibration mystery... Why are DeltaE errors weighted to the high end, when they are supposed to approximate how we see? If I have a +10% green reading at 20% stim it may only give a DeltaE of 1, but if I have the same reading at 100% stim it may give a dE of 3? These numbers aren't exact, BTW, I just made them up for illustrative purposes.

I've been wondering the same thing Chad.

All I can figure is that it is trying to account for meter errors at lower light levels??

Opening a can of worms...
 

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Quote:
Originally Posted by Chad B /forum/post/15571999


I fully agree that error is more visible at the low end (with the exception of abruptly discolored bright whites due to clipping), which brings me to a great calibration mystery... Why are DeltaE errors weighted to the high end, when they are supposed to approximate how we see? If I have a +10% green reading at 20% stim it may only give a DeltaE of 1, but if I have the same reading at 100% stim it may give a dE of 3? These numbers aren't exact, BTW, I just made them up for illustrative purposes.

It may boil down to which dE you are using... dExy or dEuv? (there are dEs for other color spaces as well, but in our world, you see xy or uv the most often. uv should be more perceptually accurate than xy. If you are seeing the sort of thing you are describing and dEuv is being used, I'm not sure why that would be happening. But color spaces ALL have their quirks. I can't say that I've noticed unrealistically low dEs at lower luminance levels while using dEuv.
 

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Quote:
Originally Posted by Doug Blackburn /forum/post/15582859


It may boil down to which dE you are using... dExy or dEuv? (there are dEs for other color spaces as well, but in our world, you see xy or uv the most often. uv should be more perceptually accurate than xy. If you are seeing the sort of thing you are describing and dEuv is being used, I'm not sure why that would be happening. But color spaces ALL have their quirks. I can't say that I've noticed unrealistically low dEs at lower luminance levels while using dEuv.

I'll do some experimenting with dEuv. I've been using dE 1994, and I thought that and dE1976 were the industry standards. But I think CalMAN has an option for dEuv.
 

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Start at 50%, but then look at what is going on at both 80% and 30%. In my experience, individual colors seem to rotate around the 50% mark, maybe high above 50% and low below 50% or vice-versa. So reading at just 50% won't tell you much about how the color is being handled but will give you a good starting point.


Dan
 
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