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

> > Also, keep in mind that to scan RELIABLY you
> > need to scan at around 2x the resolution you
> > are trying to scan...so to reliably scan 4k
> > per inch, you would need to scan at a resolution
> > of 8k per inch.
> Line _pairs_ per millimetre already account for this.  So to scan
> 120 lp/mm,
> you need 120 pixels per millimetre.


Big sigh.  YOU ARE ABSOLUTELY INCORRECT.  Line pairs DO NOT already account
for this.  I've "discussed" this with you before, and you didn't get it then
either.  It's simple sampling theory, and is a fact.  The term "reliably" is
what you are not understanding.

I can take a target of lines, at 120 LINE PAIRS per mm (which means a black
line of 0.004167 mm and a white line of 0.004167 mm, which added up make a
line pair of 0.0083mm) and sample it at 120 pixels per mm and can orient it
such that every pixel sees nothing but gray, and in this case YOU WILL NOT
DETECT ANY LINES, and hence it is NOT reliable.  That is why you NEED 2x the
sampling rate to detect something RELIABLY.

Do you really not understand this?


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