I'm a little confussed. I'm tracking my target RGB luminance/gamma curve but on the RGB levels graph blue is measuring signifigantly lower. Visually the grey scale could be better but it is not as bad as the RGB plot would indicate.

Is there a frequency limit for the DIY HCFR probe?

This is a measure of a 1280x720p@72Hz signal. I don't have this issue at 60Hz. Grey scale and luminance go hand and hand with RGB levels at 60Hz.

http://www.wideopenwest.com/~aifryia/Pictures/Lum75Hz.jpg

Interesting question... I have an HCFR probe, but no means to check it at 75Hz...

That being said, the fact that your luminance curves follow your target nicely doesn't necessarily mean the RGB curves should line up as well... each luminance curve is normalized to ITS OWN INDIVIDUAL luminance reading at 100% stimulus, so the luminance curves by themselves give you no indication whatsoever how well they're balanced to each other... that's why on the luminance curves they ALWAYS converge at 100%...

That being said, it may be that the way they all have the same curvature is why your RGB levels are at least nice and flat, they're out of balance with each other by similar errors across the board...

It wouldn't surprise me if 75Hz operation is a different mode that needs its own calibration which doesn't affect the other refresh rates... but that's higher level than my knowledge...

Well I checked grey scale again. I adjust the greyscale using the RGB levels the color shifted from neutral grey to a decidedly blue cast.

The RGB graph in my 1st post are the measured levels that give a visually good grey scale.

So something in the measurement chain is not correct. I tend to believe the luminance graph to be the more accurate measure based on my visual observations. The RGB level measures are just too far off.

Well, I probably won't be able to get you all the way through to success, but I'll take a stab at starting it anyway...
Let's start with, what's your TV, and what are you calibrating the HCFR Probe against?

When I had a CRT, I ran at 72Hz and didn’t notice any issues. Of course, I built my cal file from a reference probe that also used the same 72Hz. My PJ and DV LCD won’t do 72-75 Hz. I believe the LCD will sync and throw up an image but I’m pretty sure it will frame rate convert down to its native 60Hz.

There isn’t any change your reference setting got changed? (D55/D65/D75)

Dave

Dave,

That was the first thing I checked D65 703.REC. When I toggle the display to 60Hz it tracks perfectly. The only difference between my 60Hz and 72Hz setting is that I defocus blue at 60Hz.

I'm using a NEC XG cal file. My PJ is a G70 CRT and uses the same tubes as the NEC so the cal file should be good although I don't know what scan rate the cal file was recorded under.

Anthony

I don’t know if you have access to another colorimeter, but perhaps creating a new cal file with another reference @ 72 Hz would help. I also wonder if defocusing blue could be an issue, you mention you set that differently for 60 vs 72 Hz and it’s the blue channel that seems affected most.

I can see how a scan rate change may indeed change the output for a phosper based raster scan device. The raster will spend less time exciting a given phosphor at higher scan rates.

Also, you may try the NEC-6PG cal file or the one I attach here. It’s likely the Y will not be representative in a absolute sense, but may be fine in a relative sense.

Dave

Dave,

Thanks I'll give that cal file a try. I have a SpyderII I stopped using because it was off reading Red too low. Perhaps I'll plug it in and see what it does.

When I switch from 60 to 72Hz I get less light output as expected. I wasn't expecting the error in color measurement.

Dave's a way better helper than I am... I'm bowing out here... though I'll be watching for my own benefit...