Digital BW, The Print

Ernst writes:

> In practice however the narrow band filters are
> not that narrow ...

They don't have to be.  The problem exists no matter how broad the filtering
is.

> ... our eyes and brain are based on tri stimuli
> as well (but a bit more complicated) ...

That's why we cannot tell the difference between yellow and a mix of red and
green.  An alien species might wonder why we insisted that both were the
same, when they could easily see the difference.

> So that digital replication of the Tri X curve
> will satisfy a lot of us ...

It might.  But it is very important to understand that Tri-X cannot be
_duplicated_ by any manipulation of RGB.  This is one of the fundamental
notions that seem to escape many photographers, and as a result they reach
all sorts of wildly inaccurate conclusions about what digital photography
can or cannot do.