Digital BW, The Print

In a message dated 6/11/07 5:31:10 PM, cieloblu@... writes:


> This may be a bit off topic...however, does anyone know a good way to
> set the white and black point in a digital projector? My black and
> white images get slaughtered in digital projection even though they are
> created in my monitor calibrated computer system. We have tried a 21
> step grayscale and it is roughly okay. But delicate detail in shadows
> and highlights can still get abolished. Help!
> 
Are you attempting to set black and white luminance (brightness of each) or 
black and whitepoint (color balance of white and black)?

Spyder2PRO calibrates projectors, but does not attempt to control these 
rather variable elements of it.

Black luminance for a projector is defined by room lighting (ambient light). 
A brighter room means a weaker black as the screen gets less dark. White 
luminance varies with how far the projector is from the screen, how bright the bulb 
is, etc, but the eye adapts to this very quickly, and no adjustment is needed 
unless multiple projectors are to be matched. Black balance can only be 
adjusted by RGB Bias controls, which few projectors have, and few users would need 
to adjust even if they had them. White balance is controlled by the eye's 
whitepoint adaptation. Unless you are running two projectors at once, there is 
really no reason to work with RGB gains on a projector, as your eye will adapt to 
whatever is there very rapidly, including making a colored wall look white if 
you project on it. So, given the variable and adapative nature of all these 
factors, they are not controlled as part of projector calibration. There is a 
tech tip on this topic on the ColorVision website, if you want to read a bit 
more.

http://www.colorvision.com/learn_expert.php


C. David Tobie
Product Technology Manager
ColorVision Business Unit
Datacolor Inc.
CDTobie@...
www.colorvision.com



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