OLED LUT Creation - AVS Forum
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post #1 of 4 Old 06-21-2013, 09:05 AM - Thread Starter
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Hi,

I just got my paws on an 8-bit OLED panel. I'm an engineer and I'm actually working with the panel itself. I have the option with this panel to set a 1-D LUT for each RGB channel individually. Here's my idea of how to calibrate...

1.) Using the factory default settings, display fullscreen Red, Green, and Blue at all of the IRE points that I am able to set for the 1-D LUT's.
2.) Use a Minolta LS-100 to measure the luminance at each of those points. (Yeah, I know... It's expensive... any other ideas?)
3.) Plot the gamma curve for each color channel that the LS-100 measures.
4.) Compare the measured gamma curves to the desired 2.2 curve and calculate the error between the two.
5.) Program the correction factor for each point on each curve back into the OLED panel.
6.) BOOM! I'm calibrated.

So... I realize that this method would create desired gamma curves for each individual color channel. However, this would not guarantee a good white balance. So I would have to calculate the luminance values that I should be reading for each color that would ensure a good overall white balance. I realize that I would probably need a spectrometer to verify that my target points for the LUT's actually yield a proper white balance.

Does anyone see any big holes in this idea for calibration?

I'll upload my findings as I get them.
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post #2 of 4 Old 06-21-2013, 01:26 PM
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Basically I think you have a grip on the issues.


This will not calibrate your white balance to any specific color. If the screen is too blue or too red, this will not fix that.

This will make your grayscale consistent and should get you a good gamma response, but white balance is a much bigger issue than perfect gamma and as you already determined this does not address white balance in a meaningful way.

Joel Barsotti
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post #3 of 4 Old 06-21-2013, 01:50 PM - Thread Starter
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Okay! Great. So then maybe I could modify my method to use a spectrometer to calibrate the white balance at the highest IRE level of my LUT's. At that point, I could just forget about white balance and create the rest of the LUT points using the method above. And as long as I adhere to a gamma of 2.2 in each channel, then white balance should theoretically be good throughout the IRE spectrum.

Are these reasonable assumptions?

Calibration is so cool!
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post #4 of 4 Old 06-21-2013, 02:04 PM
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In theory that's correct.

In the real world, sometimes primaries will shift around in chromaticity as their luminance levels change and their also maybe issues where white doesn't exactly equal R+G+B.

When measuring color, the most basic way to quantify color is XYZ, a luminance meter only measures Y values.

White's X, Y and Z values for 100% should be the sum of the X, Y, and Z values for Red, Green and Blue.

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