Digital BW, The Print

> Message: 10
> Date: Fri, 28 Nov 2003 11:52:28 -0800
> From: "Paul D. DeRocco" <pderocco@...>
> Subject: RE: Re: RGB Convert to Grayscale
> 
>> 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.

Paul,

He isn't arguing in order to prove you _wrong_... he is arguing with you
because he wants to _argue_.

This is a guy who argued on USENET for days that you can get a better
understanding of the optical performance of a particular lens by reading the
manufacturer's MTF curves over actually using the lens.

He doesn't do B/W inkjet printing--he is here to fan the flames. Look at the
archives for the other capture spats-- you will see his posts, ad nauseum.

Oh yeah, you might want to ask if he actually has any experience with
digital capture...

Jon