Digital BW, The Print

Peter writes:

> But the lack of that precision may not have any
> practical effect.

It doesn't require much precision.

It's very easy to demonstrate.  Take a picture in black and white using a
narrow-band color filter.  Those are not difficult to find.  Then take a
picture of the same scene in color without a filter.  Then try to convert
the color image to B&W in a way that duplicates the same shades of gray you
see in the B&W image taken with the filter.  You'll find that it cannot be
done.

> The reason why you need to provide empirical
> evidence is that you need to show that what you're
> talking about has any relevance in the real world.

Only to you.  The real-world relevance is self-evident to me and to several
other people.  The fact that you do not see it doesn't mean that it isn't
there.  See the example above, which is about as real-world as anything ever
gets.