Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!netsys!lll-winken!arisia!tow
From: tow@arisia.Xerox.COM (Rob Tow)
Newsgroups: comp.sys.mac
Subject: Re: scanned images --> 256 greys
Summary: Use Digital Darkroom
Keywords: Image Processing Histogram Equalization Digiatl Darkroom
Message-ID: <632@arisia.Xerox.COM>
Date: 23 Feb 89 17:16:07 GMT
References: <894@fornax.UUCP>
Reply-To: tow@arisia.UUCP (Rob Tow)
Distribution: na
Organization: Xerox PARC
Lines: 34

In article <894@fornax.UUCP> mcdonald@fornax.UUCP (Ken Mcdonald) writes:
>I have some pictures scanned with AppleScan, that I want to convert to 256
>grey levels.  Unfortunately, AppleScan only seems to support 16 grey levels,
>so what I've done is scan the pictures at very high res, and now I want to
>reduce the res, and in the process smooth the greys out.  Any ideas?
>
>Thanks for the help,
>Ken McDonald
>{...!ubc-cs!mcdonald@fornax.uucp}

I suggest reading the file into Silicon Beach's "Digital Darkroom", and 
playing around with the histogram.

Digital Darkroom supports loadable code resources for image acquisition
and for image processing filters - it is a breeze to write your own filters
in Lightspeed C and do whatever custom twiddles you want.  I've used this
to add Fourier, Walsh, and Haar transforms to the program, and to add
image acquisition maodules that read the formats we use for color pixelmaps
here at PARC.  

If you have LSC, you may easily write a nonlinear reduction/smoothing
module that would nicely do what you want.



---

Rob Tow
Member Research Staff
Electronic Document Lab
Xerox PARC
3333 Coyote Hill Drive
Palo Alto, CA 94304
(415)-494-4807