Digital BW, The Print

Steve Kale wrote:
> Thanks.  I guess I get the notion of, say, 50% red, 25% blue, 25% green.
> The luminance stays the same and we are choosing the weighting of RGB.  But
> what about a channel value greater than a 100% or negative channel values?

Perhaps I'm still not understanding something, but I'm not convinced 
that making the numbers add up to 100% will necessarily keep the 
luminance the same.

Consider an image that was pure red.  Using your numbers above, you keep 
50% of the red value and don't add anything else because there is no 
blue or green.  At that point your image would (I would think) have only 
half the luminance of the original.

	Walt