JVC RS-1 With VideoEQ - AVS Forum
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post #1 of 6 Old 09-28-2011, 05:02 PM - Thread Starter
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Calibrating the projector itself. Starting with Natural color temp. Using offsets at 30 ire, I have to turn green and red all the way down to -30. I don't think that is right. Using the RGB controls under user 1 gives good results at 80 ire.
Hooking up the videoeq. I get a good grayscale @2.2 gamma. Switching to the color gamut, everything is good except blue luminance. It is way lower than red or green. I am not sure what I am doing wrong.
Equipment: Colormunki with Calman 4.2 Approx 12" from screen.
Screen: Carada BW 110".
Chain: Panasonic BD 85 into Onkyo PRSC5508 (Through Mode) into Video Eq then into Projector.
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post #2 of 6 Old 09-29-2011, 09:50 AM
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It's not clear from your post if blue luminance was too low directly from the projector without the processor in the path. If it is, then the processor is not involved in any way.

There's not much you can do when blue luminance is too low. There are really only a couple of things you can try:
1) Reduce contrast a few clicks at a time and re-measure to see what red, green, and blue luminance are... if blue improves and red and green stay pretty good, then keep reducing Contrast until blue gets to where it should be. This is obviously making the white point darker so if there's an adjustable aperture you'll probably want to open the aperture to compensate for reducing Contrast. This works because many displays "run out of gas" in one color before the others. You can also see this in an RGB balance graph that shows the relationship between red, green and blue for each grayscale step. If rgb match in balance well up to 90%, then blue starts to fall off while red and green stay strong, that's an indication that blue is simply "running out of gas" before red and green are maxed-out.

2) You can try increasing the Color control -- this MAY help by increasing all 3 colors' luminance... you'd then use the processor to bring red and green down to match blue. But Color controls don't always do what you want or need so you may find that this does little or nothing to help.

As for the other problem -- you may find you just started with a color temperature setting that was too warm. Select the next "cooler" step -- that will increase the amount of blue and you'll probably not have to reduce red and green at all or at least not nearly as much. You always want to start with a reasonably close color temperature setting... the one closest to 6500K. You want to measure that without the processor in the signal path. If you then put the processor back in the signal path and re-measure. If the color temp changes, the video processor is changing it because the settings aren't all reset from some previous calibration... the processor should NOT change anything if you haven't made any adjustments to it. If there are changes between projector measurements and measurements with the processor in the path, then the processor is not set or reset to the "default" "no adjustment" settings.

"Movies is magic..." Van Dyke Parks
THX Certified Professional Video Calibration
ISF -- HAA -- www.dBtheatrical.com
Widescreen Review -- Home Theater & Sound
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post #3 of 6 Old 09-29-2011, 03:07 PM - Thread Starter
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Thanks for the reply. I thought I knew what I was doing, but that is what makes me dangerous. I will try again.
When you use the offsets in the projector, do you try to just level match the 3 primaries or are you level matching them and trying to get to the 2.2 gamma?
Without the processor, the projector has an average gamma of 1.7. I have to use the videoeq to achieve the 2.2.

I never played around with the color gamut to see if the blue luminance was too low. Maybe I will check that out with just the projector alone. I see in Calman that the luminance for primaries is the most important thing. Should I bring red and green way down to match? I leave these at the 0 mark.
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post #4 of 6 Old 09-30-2011, 07:55 AM
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How you deal with the settings depends on the display device itself and the software you are using.

Color luminance is not "the most important thing" - grayscale is "the most important thing" then color luminance, then color xy (or hue & saturation). But a big hue/saturation error can easily overcome a smaller color luminance error so it's a slippery slope to try to say one thing is more important than something else.

Using CalMAN, you'd ideally want all color luminances to be "0". If they can't all be made to be "0" (assuming you are using the color luminance bar graph where the bars can be negative or positive (above or below 0), the next best thing is to try to get them to all be the same (like all 5% above zero or all be 7% below 0) but if the best you can do is to have all of them WAY above or WAY below zero, that's going to look really bad and you're better off NOT making them all equal. A video processor can't make any color luminance brighter than the TV or projector can make it. So if you have one color that is, say, -30%, you essentially cannot fix that (unless it is caused by the "running out of gas" issue explained earlier). The only possible fix might be to try increasing the Color control or some other setting to see if the control happens to raise the lowest luminance problem high enough to get to "0" - without worrying about the other colors getting too bright. Once the lowest color is up to "0" you can reduce the luminance of the other colors in the TV/projector and if you can't fix all of that in the TV/projector, you still have the video processor for final adjustments. The function of controls varies from one model to the next so you always have to check to see if something like raising the Color control helps -- in some cases it won't do anything helpful OR it might help luminance but create other problems so you might have to balance the "fixed" problems with the "worsened" problems so neither one is visible. All this stuff is why pro calibrators exist - it can seem overwhelming in the beginning.

Yes, you can use the gain/offset (or high/low or some other terms the display manufacturer might use) controls to improve gamma... if gamma is too low (i.e. 2.0) and you want it higher, 2.0 means everything between black and white is too bright (gamma does not change the black point or white point, it changes the shape of the curve connecting the black point to the white point). So you can darken red, green and blue using the gain/offset controls to raise the gamma number -- again these controls work differently from display to display so you might lower all of them the same amount in some displays while other displays may require different amounts of reducing the settings in questions.

When calibrating with a video processor, you want to calibrate the projector first avoiding huge adjustments to anything. If there's a HUGE error somewhere, you might want to fix half of it in the projector and the other half in the processor. The projector need not be "perfect" before going to the video processor, but you should eliminate problems so that the projector is reasonably OK before moving on to calibrate the video processor... and you want to start with the video processor being "reset" so it isn't changing anything before you begin measurements or adjustments. If the processor has previous settings in it, you can get confusing or conflicting measurements.

"Movies is magic..." Van Dyke Parks
THX Certified Professional Video Calibration
ISF -- HAA -- www.dBtheatrical.com
Widescreen Review -- Home Theater & Sound
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post #5 of 6 Old 09-30-2011, 08:32 AM - Thread Starter
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Thanks, will play around with both and start again. Good thing I actually like doing this. I believe that is sign of insanity though.
Thanks again for your help. Without this forum and its supporting members, I would still have an oversaturated display.
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post #6 of 6 Old 10-06-2011, 03:00 AM - Thread Starter
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Checked after I saved the "Cinema" to user1 setting, on the offsets green and red were at the full -30. So, I guess this is normal. Getting it close made much less adjustment with the VideoEq. Picture is as good as I am going to get it.
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