Digital BW, The Print

> From: Austin Franklin [mailto:austin@...]
>
> I agree with your differentiation between colorimeter and
> spectrophotometer
> (except that I'm not sure that a spectrophotometer always reads the entire
> visible spectrum, my understanding is the distinction is that it has more
> than three "bands"...kind of like the difference between bass & treble
> controls and a graphic equalizer).
>
> But, I believe any of them can be densitometers as well, if they read
> density.  At least the X-Rite 810 I have reads RGB as density, and they
> actually call it a densitometer (not even a colorimeter).  I would also
> classify a scanner and a digital camera as densitometers (simply
> uncalibrated), and ones that use RGB filters as colorimeters as
> well...which
> brings up an interesting question (related to scanning), at least
> to me it's
> interesting.  Is there any advantage of using a larger number of
> bands (like
> a spectrophotometer) in color film scanning.  I am not sure, as I am no
> color expert.

Someone else (sorry, I've deleted the message) mentioned that a CMY
densitometer differs from a colorimeter in that it has three narrow-band
sensors, instead of three sensors with overlapping spectra to mimic the
eye's response. The latter would be useful for measuring the appearance of
any light source, while the former would only be useful when measuring inks
or dyes with well-known absorption spectra. If you tried to use a CMY
densitometer for profiling your monitor, for instance, it would probably do
a lousy job, because it would be subject to gross metamerism.

If this is the distinction, then I would expect that a CMY densitometer
ought to do a perfectly good job on B&W prints, but I'd rather have a more
versatile instrument.

As to your last question, I doubt having a large number of bands would be
useful in color film scanning. It would be very cool to have a camera with
lots of bands, though.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...