AVS Forum Special Member
Join Date: Aug 2000
Location: Houston, TX, USA
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Color-correcting with screen paint is both simple and complicated at the same time.
It is simple in the sense that a pink screen (which is a color selective gray screen) will reduce blue, green thus increasing the relative amount of red in the image. This rather simple solution can make a 9000K+ projector closer to 6500K without losing any contrast ratio.
It is complicated because we are dealing with non-ideal blackbody radiators that don't give out a uniform spectrum. The UHP, NSH, etc's blotchy spectrum is often reflected in poor CRI numbers which isn't a problem with normal white screens. But, as soon as colorant is added the exact results will be rather unpredictable unless spectography is done of both the bulb and the paint's transfer function characteristics. If there is an odd ball emission from the bulb that is keeping the projector from outputting a solid image, a pigment could be added to the paint to squelch the offender. However, we only have three color sensors in our eyes that can't distinquish the all the nuances or the various wavelengths of light.
I personally have done pink screens for my friends with good success; but those were pretty much eye-balled guesses. Also, my friends miss out on the benefits that the gain of professional screens have to offer. (Until a Pinkhawk comes out, I think I will be giving up the pink screen thing.)
Bottom line: to do really good exact work will require really good measurement equipment and the appropriate paint, but the idea is sound and decent results can be had with a little trial and error.
Ps. I am very suprised to here that the blue gray screen is working so well for your 11HT. The 11HT has a blue shift like 99% of the digital projectors out there. A blue screen should only further cool the image.
The Mothership is now boarding.