Path: utzoo!utgpu!water!watmath!onfcanim!dave
From: dave@onfcanim.UUCP (Dave Martindale)
Newsgroups: comp.sys.amiga
Subject: Re: amiga on a mac ii budget- the sequel
Message-ID: <15902@onfcanim.UUCP>
Date: 27 Aug 88 03:58:17 GMT
References: <575@super.ORG> <3075@tekig5.PEN.TEK.COM> <179@kesmai.COM> <6536@bloom-beacon.MIT.EDU> <11503@cisunx.UUCP>
Reply-To: dave@onfcanim.UUCP (Dave Martindale)
Organization: National Film Board / Office national du film, Montreal
Lines: 37

In article <6536@bloom-beacon.MIT.EDU> cthulhu@athena.mit.edu (Jim Reich) writes:
>Really?  People keep talking about this, but I
>just can't understand why people need six trillion colors, except for
>bragging purposes.  I'll admit that easy access to 256 colors would be
>nice, but you just can't tell the difference with more.  Actually, I'm kind of
>curious as to why one would need 8 bits of color. Making a bar graph with 4097
>bars on it?  Can you really see the difference between a HAM smooth shade and
>an 8 bit smooth shade?!?!?!?  

It's generally accepted in the computer graphics community that if you
want accurate display of "photographic-looking" images (which includes
both photographs of real objects and high-quality calculated images),
without artifacts like visible bands across areas that should be smoothly
shaded, you should have 24 bits of colour, not 8 or 6.

And 24 bits works so well partly because the light output of a CRT is
roughly an exponential function of the input voltage, effectively giving
an 8-bit linear digital-to-analog converter extra resolution in the dark
areas, where it needs it, and less in bright areas, where it doesn't. 

If you're working with a signal that doesn't have this non-linearity
working for it, for example a camera, you really need more than 8 bits
per colour.  12 seems sufficient, 8 is definitely not.

What does all this have to do with an Amiga?  Well, there really are
people with a need for 24 bits or even more per pixel.  There are
24 bit/pixel graphics cards available for the IBM PC market, complete
with genlock and frame-grabbing capability.  They're starting to show
up for the Mac II as well.  This will make the machines expensive, but
if you need a 24-bit workstation then you need it, and the Amiga is
simply out of that market if it can't provide the colour resolution.

(Where I work, the workstations are all 24 bits/pixel, and the input
scanner and film recorder are 36 bits/pixel).

	Dave Martindale