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- Path: sparky!uunet!mcsun!ub4b!news.cs.kuleuven.ac.be!blekul11!stud16
- Newsgroups: comp.sys.amiga.hardware
- From: stud16@cc4.kuleuven.ac.be (Kurt Haenen)
- Distribution: world
- References: <BxAvtu.1F9@fc.hp.com> <1992NOV10.093926.5786@TDB.UU.SE>
- Date: Wednesday, 18 Nov 1992 14:57:39 +01
- Message-ID: <1992Nov18.144917@cc4.kuleuven.ac.be>
- Organization: K.U.Leuven - Academic Computing Center
- Subject: Re: Three AGA questions.
- Nntp-Posting-Host: 134.58.8.1
- Lines: 56
-
- In article <1992NOV10.093926.5786@TDB.UU.SE>, t92etr@tdb.uu.se writes:
- > Steve Koren (koren@fc.hp.com) wrote:
- > : Mattias Dahlberg (matt-dah@dsv.su.se) wrote:
- > :
- > : > since then 256000 will be the number of pixels. But shouldn't it
- > : > be 262144 on all higher resolutions...?
- > :
- > : What's a couple of thousand colors here or there? :-) But seriously, I
- > : think the correct value is 2^18+64. (Ie, there are 64 base registers
- > : you can set to whatever you want, and you can HAM your way to 2^18 more
- > : colors beyond those).
- >
- > Well,those 64 base registers are probably part of the 2^18 colors.
- > I think that the number 256000 comes from confusion with 256k (256*1024=262144).
- >
-
- Well, maybe I'm wrong, but I'll try anyway ...
-
- The way I thing HAM8 works (correct me if I'm wrong, but I'll base
- my statements upon this info):
-
- - You have 64 (= 2^6) base registers.
- - You have 4 modes (2 bits for the mode) : choose a base register,
- modify red/green/blue component.
- - Modifying the component is done by keeping the lower two bits of
- that component as they were for the previous pixel and changing
- the upper 6 bits as indicated in the bitmap.
-
- Well, with these assumptions, I think the number of possible colors
- for the HAM8 mode is about 16 Million (i.e. 24bit colour). We can
- choose the base-registers in such a way that every possible
- combination of the lower 2 bits for every component (ie. 6 bits = 64
- colours) are found in the base-registers. The upper 6 bits of each
- component can be changed using those HAM-change-component modes, so
- every colour in the 24 bit space can be created as follows :
- - Select the base register with the correct settings for the
- 2 lower-bits of each component
- - Change the upper 6 bits of the red component to the value you
- want it to be
- - Same for the green component
- - Same for the blue component
-
- Note that this won't be done in practice, since you would need 4 steps
- to get the colour you want, *BUT* it shows that (if the resolution
- would be large enough) HAM8 could show the full 24 bit space.
-
- +----------------+-------------------+------------------------------------+
- |/////\\_____\\\\| | |
- |//// /_____ \\\\| Kurt Haenen | Tjee, with this new cruncher, |
- |/// /\____//\\\\| Homsemstraat 53 | I can put two times as many disks |
- |\\\/\ \ / / \\| 3891 Borlo | in one box than I used to ... |
- |\\\/\\ \ / /\/\\|___________________|____________________________________|
- |\\\/\\\/_\/\/ //| | |
- | Kurt \/_\ / ///| EMAIL : STUD16 @ CC4.KULEUVEN.AC.BE | 2B || !2B T^ = |
- | Haenen \\\/// | FHGAA99@ CC1.KULEUVEN.AC.BE | THE QUESTION ! |
- +----------------+---------------------------------------+----------------+
-