doesn’t acutance have something to do with edge enhancement
in development?

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-----Original Message-----
From: pdml-boun...@pdml.net [mailto:pdml-boun...@pdml.net] On Behalf Of
Godfrey DiGiorgi
Sent: Friday, December 31, 2010 12:47 PM
To: Pentax-Discuss Mail List
Subject: Re: Question of terms and/or English


>From the dictionary:

acutance : (noun)
the sharpness of a photographic or printed image.
• a measure of this.
ORIGIN 1950s: from acute + -ance .

As I use the terms, acutance differs from sharpness in that I use sharpness
to refer to the perception of detail where I use acutance as the measure of
detail. Resolution is a more specific term, usually calculated rather than
observed but it can be either. If resolution is "observed", then it is a
synonym for acutance.

Example: A 6 Mpixel sensor of size 16x24 mm has 2000x3000 photosites, so its
spatial resolution is nominally about 63 line pairs per mm to first order
calculation (half the number of photosites per mm). However, given the
addition of an antialiasing filter and other factors like the algorithm used
in the conversion of captured data to a viewable form, the number of line
pairs per mm that can be obtained usually runs about 10-20% less, so the
acutance of that sensor is likely in the 47-52 l...@mm range. That sensor
assembly can produce images which display a lot of sharpness in perceptual
terms ... meaning the images have good edge definition (a product of
contrast differentials over short spatial dimensions ...) to our eye but
that actually don't have an enormous amount of resolution.

Make sense?


On Fri, Dec 31, 2010 at 9:11 AM, Boris Liberman <bori...@gmail.com> wrote:
> Hi!
>
> I kind of know what contrast, resolution, sharpness is. But what does 
> "acutance" mean?
>
> Thanks in advance.
>
> Boris
>
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