Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Anthony 
Atkielski" <anthony@a...> wrote:

> However, it's certainly possible to develop an imaging
> device that is sensitive only to spectral yellow, 
> and does not respond to red or green. Such a device, 
> when presented with a scene that contains both
> spectral-yellow-lit areas and areas lit in red and 
> green, will see only the spectral yellow areas as being
> lit.

But that's just as artificial as the single-wavelength LED example I 
used.   You have not demonstrated this has any bearing on the real 
world problem of mapping color film to black and white.    I asked 
you before to identify some wavelength that would "fall between" 
sensitivity of some color-triplet system (color film or digicam) 
that would get recorded on b+w film.





> > Are you saying that black and white film will
> > record this differently from an identical yellow
> > created by say mixing cadmium yellow paint?
> 
> YES!!  (If cadmium yellow is a spectral yellow, and I think it is.)
> 
> B&W film--as well as color film and CCDs--records light
> differently based on its frequency, not based on how it
> might be represented in RGB.  If the sensitivity peaks
> at spectral yellow frequencies but is lower and unequal
> at red and green frequencies, the B&W film will render 
> different "types" of yellow with different luminosities.

Give a specific example of a wavelength that would fall betweeen the 
peaks in the manner you describe so we can test it.    I think 
you're describing something purely conjectural that has no bearing 
on the real world, but I'll be happy to be proven wrong.