Digital BW, The Print

Tom Baker writes:

> Would you provide an example of a b&w image that could only be
> captured with b&w?  Most of us would like to see such an example.

I guess you missed my explanation about the narrowband yellow filter.

Shoot a scene in straight B&W with a narrowband yellow filter.  The
result will be impossible to duplicate with any conversion of RGB to
B&W, for most scenes.

The reason is simple:  In the first case, parts of the scene that are
truly yellow (spectral yellow) will look bright, and parts of the scene
that are not yellow, or that are only perceptually yellow (green and red
mixed together) will look dark.  In the second case, anything that is
truly yellow OR red and green will look bright.  There isn't any way to
achieve the first result in the second case, because the necessary
information from the original scene is gone.

Since many B&W effects depend on special filters, a lot is lost if you
constrain yourself to conversions from RGB.  Black and white isn't as
simple as it appears to be.

More obvious examples can be given.  You can't get infrared B&W from any
conversion of RGB, nor can you get UV from RGB conversion.  The reason
for this is the same as indicated above.