RE: Digicam

["gary" <gsellani@xxxxxxxxxxxxx>]

Your explanations would be much clearer without the "convolution in one
domain is multiplication in the other domain" statement (which we know
anyway).  Your diatribe on the effects of MTF is just an extension of the
idea that "pixels have width", which was something I agreed with from the
beginning.

Now doesn't the unsharp mask (to what ever degree), reduce the effects of
the "width" (or in reality sharing information) between pixels.

> -----Original Message-----
> From: owner-scan@leben.com [mailto:owner-scan@leben.com]On Behalf Of
> Kennedy McEwen
> Sent: Saturday, June 15, 2002 7:28 AM
> To: scan@leben.com
> Subject: Re: Digicam
>
> The most significant differences between the audio analogy and the
> imaging case are:
>
> 1.  In audio the analogue prefilter is single sided since the analogue
> circuits can only respond to their input after it has been received,
> whilst in the imaging case all of the samples occur simultaneously and
> the filter is nominally symmetric about the spatial frequency axis in
> all orientations.  Of course, if the optical system includes certain
> distortions, such as coma, then the implied filter becomes slightly
> asymmetric also.  In modern high performance audio systems the
> asymmetric filter is replaced by oversampling and application of a
> symmetric FIR digital filter, making it even more similar to the imaging
> case in this respect.
>
> 2. Being completely separate functions in the audio analogy, the filter
> can be tailored to meet the constraints of the sampling system, with a
> brick wall filter.  In imaging this is not so easy to implement,
> although it is possible, and the filter is normally determined by the
> constraints of the optical MTF and the shape and size of the pixel
> itself.
>
> --
> Kennedy
> Yes, Socrates himself is particularly missed;
> A lovely little thinker, but a bugger when he's pissed.
> Python Philosophers
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