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[filmscanners] Re: Film resolution - was: Re: 3 year wait

Austin writes:

> But, one thing that is VERY important is
> there is a difference between sampling sine
> waves and square waves.

Not from the standpoint of the Nyquist theorem, which applies to any
periodic signal of any shape.

> Though at Nyquist, you guarantee detecting
> the frequency, you do not guarantee full
> amplitude.

You can reconstruct any periodic signal by sampling it at twice the
frequency of the highest-frequency component of that signal.

> To sample square waves, and GUARANTEE getting
> at least ONE "sensor" that contains full amplitude,
> you MUST sample at 4x f ...

No, to sample square waves and reproduce them with complete accuracy, your
sampling frequency must be infinite, as true square waves contain components
of infinitely high frequency.

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