Digital BW, The Print

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Here's a nice Zeiss assessment of screen viewing of digitally captured images, extended quote:

CLN_MTF_Kurven_2_en.pdf

http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_31_MTF_en/$File/CLN_MTF_Kurven_2_en.pdf

Viewing conditions

Most likely you are viewing the images
provided as examples on a computer
monitor. This gives us reason to look a
little more closely at how the monitor
properties may influence our perception of
the images.

Image size

The 12MP digital camera used here has a
Nyquist frequency of approx. 1400 line
pairs per image height (image height
being the short side of the 24x36 format;
think of a picture in landscape format). It
takes at least two pixels to display a line
pair made up of a bright and a dark line.
The camera has exactly 2832 pixels
(2x1416) on 24 mm of image height.
The monitor would have to have at least
as many pixels to be able to display this
image information free of losses. However
we will usually have to be satisfied with a
lesser monitor performance, e.g. 1600 x
1200 pixels. The monitor can therefore
only display parts of the full image without
losses.

If one runs Photoshop on a monitor with
1200 pixels in the vertical direction,
some of these pixels are taken up by the
menu bars and the net number of pixels
seen is, for example, only 1036 pixels.
In the 100% view, in which each pixel of
the data file is represented by a monitor
pixel, only approx. one third of the image
with a height of 2832 pixels is seen,
which corresponds to approx. 13% of the
area of the image.

If the monitor diagonal is for example 21"
= 54 cm, the size of the whole camera
image in the 100% view is 76 x 114 cm.
Even if our demonstration images are
smaller in absolute units (in order not to
let the file sizes grow towards infinity!)
you should always be aware that you are
looking at parts of a poster-sized image.

Viewing distance

If the monitor has 1200 pixels distributed
over an image height of 32.4 cm, it has 3.7
pixels per millimeter. Thus the resolution
of the monitor screen is approx. 2 Lp/mm.
In the (nearly) loss-free 100% view, this
also corresponds to the camera sensor
performance: the image with a height of
76 cm is magnified 31-fold as compared
to the camera image with a height of 24
mm. The sensor's resolution limit (Nyquist)
that is determined by the number of pixels
is just less than 60 Lp/mm.

Magnified 31-fold, this also corresponds to
approx. 2 Lp/mm.

Viewing the image on the monitor from a
distance of 50 cm, the maximum
resolving power of the eye at this
distance is approx. 4 Lp/mm. In simple
terms, this is about twice as good as the
monitor image.

For this reason, images in 100% view
will never appear perfectly sharp to our
eye. Both the performance limits of the
monitor and the giant magnification of
the image for the small viewing distance
give rise to a certain degree of softness
of the image.

Viewing a 100% view from a distance of
50 cm is a very critical view of the image.
For a more realistic assessment, the
viewed distance can be doubled, for
instance.

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Hmm ... a measured analysis -- cool!

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