Digital BW, The Print

Peter writes:

> I agree with Austin.   Tell us precisely what
> information is missing.

I have, again and again.  I've just tried again with Austin, although I'm
not optimistic.

> Don't speak vaguely about the "curves" because
> we know what the response curve is of the color
> dyes used in the film.

There is nothing vague about curves.

> So we know exactly how much to compensate the
> density by for any color.

You cannot compensate in this way.  In fact, I'm not even sure what you are
talking about, since it has nothing to do with the constraints I'm
describing.  This does not bode well.

> Or put another way:  because we know the shape
> of the film's response curves there is only one
> unique point on the spectrum that will produce
> a given density in all three dyes.

Wrong.  There are multiple distributions of light energy in the original
scene that will produce identical results in the dyes.  If that were not the
case, it would be impossible to produce "yellow" by mixing red and green
light.  That only works because many different spectral distributions are
recorded identically by RGB sensors, such as film (or CCDs, or the human
eye).

If you are convinced that every unique distribution of light frequencies in
the original scene produces a unique RGB result, then explain why mixing red
and green light produces exactly the same result as yellow light, even
though they have completely different spectral distributions.

> So what's missing?

Just about everything.

> You say that other people here understand you,
> but I don't see them jumping in to clarify what
> you're saying.

They may find it difficult to explain it in a better way, or maybe they lack
my patience.