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From: holloway@drivax.UUCP
Newsgroups: comp.graphics
Subject: Re: reverse dithering
Message-ID: <2739@drivax.UUCP>
Date: Wed, 18-Nov-87 12:06:52 EST
Article-I.D.: drivax.2739
Posted: Wed Nov 18 12:06:52 1987
Date-Received: Sat, 21-Nov-87 17:19:39 EST
References: <1525@ssc-vax.UUCP>
Reply-To: holloway@drivax.UUCP (Bruce Holloway)
Organization: Digital Research, Inc.
Lines: 22
Keywords: dithering, halftone, gray scale

In article <1525@ssc-vax.UUCP> dickey@ssc-vax.UUCP (Frederick J Dickey) writes:

>My question is the following: Given the image in the dithered form,
>is there any reasonable way of reconstructing the original gray scale
>image?

1) Find the size of the dithering matrix. This should be pretty obvious, and
   usually square  (8x8 pixels is common)

2) Take each pixel in turn as the center of the dithering matrix. Then count
   the number of white pixels in the matrix, divide by the total number
   of pixels in the matrix, and you have your percentage of white for that
   pixel (from 0 to 1).

This method isn't foolproof, especially where the intensity changes quickly,
but it should serve. I'd be interested in hearing about any better algorithms.

- Bruce
-- 
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* Bruce Holloway - Terminal Netnews Addict       uunet!amdahl!drivax!holloway *
* ALBATROSS, ATARI*TROS @ Plink                            ALBATROSS @ Delphi *
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