CurtPalme.com Home Theater Forum

[bubsnews]

Hey fellas,
when you have a discrepancy between the CIE diagram and the actual x/y numbers, which one do you use?

I have my CIE diagram with primaries and secondaries spot on, but the yellow secondary has a dE value of 14. If I calibrate so the dE is under 3 like the others, then the yellow secondary falls off the mark by quite a bit.

I really don't know how to leave it, use the CIE diagram or use the dE values as how to leave my calibration.

Thanks,
George

[Nashou66]

From what I understand the dE values is the measurement of any differences the human eye can differentiate between shades of colors, the lower the vale the less the eye can tell a difference. I'd go with the lower dE values. But i am no expert.

Athanasios

[garyfritz]

Something's wrong. If you calibrate to the correct x/y value, then your dE should be zero. I believe dE is basically calculated as "distance in x/y space between your measurement and the correct x/y value."

How did you determine your x/y values were "spot on" ? Are you going by where it falls on the CIE diagram? I'd look at the actual x/y values, not where it gets drawn on the CIE diagram. I've never seen it before but I suppose it's possible something is wrong with the CIE plotter.

[Gino]

I agree, use the actual x/y values, the dots on the CIE are probably not drawn too accurately

[bubsnews]

Thanks fellas, I appreciate the input. I never looked at the actual x and y coordinates, but calibrated so that the primary and secondary markers of my projectors color space fell exactly on the markers of the REC709 color space. This wasn't exact, all looked like they were in the exact position with the exception of blue, just never could get that exactly right.

When done, I checked the dE values and all were under 1 with the exception of two, one was under 2 and the yellow secondary was 14.8. I calibrated again until the yellow secondary was below 1 but when looking at the CIE diagram, yellow as not even on the line anymore, in fact nowhere near it. It was short inside the REC709 color space triangle, looked very strange with the other 5 colors being almost perfect.

I will take a moment and go back and look at the actual x and y coordinates. Of course, I never noticed any difference between the two calibrations, even though the CIE diagram looked bad as far as yellow. Also, I had trouble dialing in the luminance for two of the secondary colors, cyan and magenta. My projector, BenQ W5000, has a range of about 2000 for luminance calibration, with the default for the secondary colors of 1200. I could not adjust enough to bring the luminance of these two secondary colors into proper adjustment, so returned both of them back to default values. The other secondary color as well as the three primary colors dialed luminance in nicely.

Thanks again for the feedback, it is greatly appreciated. By the way, anybody here familiar with the W5000?
George

[cvearl]

If this is with ColorHCFR, I was under the impression that dE is calculated with the Y (luminance) included which is the point you DONT see on the CIE. So if you are almost bang on the xy and the Y is grossly off, you can have a large dE value.

For me, I have no CMS in my Plasma and by it's design the Red and Green are pushed out into an oversaturated or "vibrant" xy coordinate. If I want to force them to be as close as possible to the xy of Rec 709 I have to crank down the color control which is lowering the overall lightness (Y) of ALL the colors relative to white's luminance (Y) and making it more incorrect even through I am getting closer to Rec 709 x and y.

Apparently it is ok to drop luminance a few clicks to help reduce saturation of the primaries somewhat but more than a few clicks can hurt the colors.

I welcome correction to this. I am new to all of this but have done a significant ammount of reading as of late on the issue.

C.