Digital BW, The Print

> From: Anthony G. Atkielski [mailto:anthony@...]
>
> RGB is worse because it collapses all the spectral energy of the
> original scene into just three numbers.  There is no way to restore that
> spectral distribution from those three numbers.  True black and white
> capture (be it electronic or film) captures an image as a function of
> the continuous spectral sensitivity of the capture medium and the
> continuous spectral emission of the image being recorded.  There is no
> way to simulate that continuous function with just three numbers.  So
> there exists an infinity of black and white scenes that cannot be
> accurately reproduced using a conversion from RGB.

Excuse me, but black and white film "collapses all the spectral energy of
the original scene" into just one number.

In theory, you can certainly acheive results with a narrowband filter in
front of B&W film that cannot be attained precisely by using an RGB sensor
and Photoshop. However, there are some practical problems:

1) You only get one particular result with a particular filter. Once it's in
the B&W domain, you've lost all ability to make adjustments to anything but
the grayscale.

2) You can't see the results of your filter choice until hours later.

3) The commercial filters used for B&W photography aren't narrowband anyway.
The blue and green ones are no more narrowband than the filters in a
digicam. The red and yellow ones are actually low-pass filters.

You may indeed like the results you get with filters and B&W film, but
there's no ground on which to argue that these results are unquestionably
superior or more correct, or contain more information.

--

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