Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!decwrl!adobe!heaven!glenn
From: glenn@heaven.woodside.ca.us (Glenn Reid)
Newsgroups: comp.sys.next
Subject: Re: Why no CLUTs?
Message-ID: <278@heaven.woodside.ca.us>
Date: 25 Sep 90 18:00:00 GMT
References: <50958@brunix.UUCP> <1990Sep25.060147.6502@d.cs.okstate.edu>
Reply-To: glenn@heaven.woodside.ca.us (Glenn Reid)
Distribution: comp
Organization: RightBrain Software, Woodside, CA
Lines: 33

In article <1990Sep25.060147.6502@d.cs.okstate.edu> minich@d.cs.okstate.edu (Robert Minich) writes:
>by rca@cs.brown.edu (Ronald C.F. Antony):
>| (Izumi Ohzawa) writes:
>|>How about LUTs (Color lookup tables)?  Do they exists on NeXTdimension
>|>boards?
>| 
>| Can you tell me what colors you want to look up that 24-bit color does
>| not bring to a screen directly without a look-up?
>
>  Believe it or not, there are plenty of legit reasons for CLUTs. The most
>interesting is probably CLUT animation. I 'spose you might be able to
>do something similar with the NeXTdimension and LOTS of computation, but it's a
>whole lot easier to just twiddle a 256x24 bit table. Seeing as visualization is
>an up and coming area, I am surprised CLUTs aren't available.

Color lookup tables are device-dependent.  If you diddle the color lookup
table and the window moves so that half of it is on a black-and-white
monitor, then what happens?

The beauty of the PostScript indirection is that it completely isolates you
from the display, which means that programs run flawlessly on any display,
even if you wrote it for 2-bit grayscale and then they came out with a 32-bit
color system.  Not even a recompile.

Animation can be nice, but there are other ways to animate that are less
device-dependent.

Glenn

-- 
 Glenn Reid				RightBrain Software
 glenn@heaven.woodside.ca.us		PostScript/NeXT developers
 ..{adobe,next}!heaven!glenn		415-851-1785