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Re: Medical Imaging Question

David Fanning, davidf@dfanning.com writes:

> This is basically what I thought, but didn't 
> have the background to support my beliefs.

    Well, the eye stuff I've culled from other sources.  Fortunately
this is not the only newsgroup with knowledgeable posters :-)

> I'm going to write it up as an article, if you 
> don't mind, so that I don't have to keep
> answering this question over and over. :-)
    Sure.  You might want to emphasise that modelling the eye as an
n-bit linear detector is a very dodgy approximation, and even using a
fixed point representation (which is closer to logarithmic seeing)
only gets you so far.  The brain is very good at outwitting simplistic
models, both by concentrating attention and by learning over time.

    I think another poster said that medics don't need the whole 4096
levels by the time they've identified what they're interested in.
Something like a chest X-ray is a classic survey problem, where you
need lots of detail, both spatial and spectral, but don't know exactly
where until after you've taken the data.  This is one of the last
redoubts of big pieces of photographic film, along with wide-area sky
surveys for transient things like comets, where the problem is much 
the same.