Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!convex!eugene!swarren
From: swarren@eugene.uucp (Steve Warren)
Newsgroups: comp.sys.amiga
Subject: Re: RGB to HAM IFF
Message-ID: <2005@convex.UUCP>
Date: 10 Oct 89 15:33:15 GMT
References: <495@nigel.udel.EDU> <333@amgraf.UUCP> <1976@convex.UUCP> <55@clmqt.marquette.Mi.US>
Sender: news@convex.UUCP
Reply-To: swarren@eugene.UUCP (Steve Warren)
Organization: Convex Computer Corporation, Richardson, Tx.
Lines: 46

In article <55@clmqt.marquette.Mi.US> kenb@clmqt.marquette.Mi.US (Ken Baynard) writes:
>swarren@eugene.uucp (Steve Warren) writes:
>>>>>   Has anyone worked out a method of converting RGBs to HAM. I have
>>>>>   three B/W images (8 bits/pixel), and I would like to covert them
>>>>>   to a HAM image. If somebody could show me the way I would not writing
>>>>>   the C-code and making it public...
>>             ...
>
>>I never used it myself, but it seems like the digiview digitizer
>>came with some software that does that (it uses a filter to digitize
>>the image in three passes).
>
>>	  {uunet,sun}!convex!swarren; swarren@convex.COM
>  Well you're close. Digi-View won't actually do the coloring for
>you. It can be used to modify the picture however in terms of
>intensity, brightness, and contrast. To take a B/W or say 16 gray
>scale picture, its best to use either Digi Paint or Photon Paint.
>Using the subtract option with either of these, you can color in the
>various shades of gray accoringly and at the end have a HAM picture.
>I've used the technique quite a bit with fairly impressive results.
>The key is to have a good B/W picture to start with. Hope this helps
>a bit.

OK, allow me to ask a few questions, because mainly I was correcting
a misunderstanding that another fellow had about the problem.

Are you saying that using Digi Paint or Photon Paint he will be able
to load in a 16 grey-scale picture and change it to a 16-level red
only picture, without doing any manual "painting" on the picture
itself?  Of course then he would have to do the same with the
blue and the green pictures.  Then the three "colorized" pictures
must be added together in such a way that R+G+B=white, and all the
variations in between.

If Digi Paint or Photon Paint can do all this, then one of these
programs will do the job for him.

But he still has to figure out how to get from 8-bits to 4-bits
per color plane.  He will probably need a better algorithm than
"divide-by-16" to get good results.

Any suggestions from image people on the best way to drop 4 bits?

--Steve
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	  {uunet,sun}!convex!swarren; swarren@convex.COM