Newsgroups: sci.image.processing
Path: cantaloupe.srv.cs.cmu.edu!rochester!cornell!travelers.mail.cornell.edu!news.kei.com!news.mathworks.com!usenet.eel.ufl.edu!news-feed-1.peachnet.edu!gatech!swrinde!cs.utexas.edu!howland.reston.ans.net!news.sprintlink.net!alfa02.medio.net!netnews.nwnet.net!serval.net.wsu.edu!news
From: "Roberto H. Bamberger" <bamberg@eecs.wsu.edu>
Subject: Re: Division of 2 images
Message-ID: <D5D3vJ.5J8@serval.net.wsu.edu>
Sender: news@serval.net.wsu.edu (News)
Organization: Washington State University
References:  <955909145907@ibm3090.bham.ac.uk>
Date: Mon, 13 Mar 1995 04:45:19 GMT
Lines: 25

It sounds to me like you are having a problem with numeric precision.
If you have two images and want to divide their values on a pixel by pixel basis, then 
you need to be careful and make sure that the data type you will
be putting the result in is of sufficient precision to store the
result without loss. 

For example, consider dividing each pixel in an image by 2. If you start with
data stored as a single byte from 0 to 255, and divide by two, then you
will have data in the dynamic range 0-127. However, if you store this as a 
single byte, then you will NOT be able to reconstruct the otiginal
data by simply multiplying by two...

> ==============================================================================
> Hi,
> Can anybody clarify to me how to divide on image by another, please?
> 
> Is it pixel(a,x,y)/pixel(b,x,y) where a and b are the images?
> I greately appreciate any help... my divisions go either too small or
> too large... :-(
> Thanks in advace,
> 
> 
> Gabriel
> 

