Re: filmscanners: which space?

["Karl Schulmeisters" <karlsch@earthlink.net>]

That's not exactly the case.  What is the case is that a particular Hue,
Intensity value - what our eyes perceive as a unique 'color value' can be
rendered with multiple combinations of RGB.  The same is not true for CYMK

So when you map from RGB into ANY color space, you essentially lose some
information.  Namely you lose the mapping back to the original value
settings.  That doesn't mean you can't get back to an RGB triplet that will
look the same, but it does mean that say if you had set the RGB triplet
value to Rx,Gy,Bz then mapped to CYMK and you went back, Rx',Gy',Bz' might
not have
x=x',y=y',z=z'.

This matters because you then can't just 'undo' any filtering you did prior
to the mapping.  Other color spaces have unique tuplet values.  This has to
do with the fact that in CYMK, intensity is mapped into the gray-scale K,
whereas in RGB, intensity is a function of the particulare RGB values.





----- Original Message -----
From: <TREVITHO@aol.com>
To: <filmscanners@halftone.co.uk>
Sent: Wednesday, May 23, 2001 1:38 AM
Subject: Re: filmscanners: which space?


>
> In a message dated 22/5/01 3:05:24 am, mlidaka@ameritech.net writes:
>
> << We don't disagree - I work primarily in LAB and CMYK myself, for both
web
>
> and print, but then convert to RGB for final contrast adjustments and to
>
> send to the printer.  >>
>
> Dear Maris
>
> To the best of my knowledge RGB to CMYK is a one way conversion. CMYK to
RGB
> although possible will cause problems. Although its OK for web use and ink
> jet printers have you tried litho print when it needs converting back
again?
>
> Bob Croxford
> Cornwall
> England
>
> www.atmosphere.co.uk