Re: I wonder how Dpreview will handle....

David J Taylor added these comments in the current discussion du
jour ...

The first prints I ever made had no pixels whatsoever - just a
black-and-white negative with a mush of grain!

That's what I like about you, David, you have a sense of humor
(humour?) and can lighten up any discussion possitively.

I rarely print, so for me the most important measure is the
number of pixels in the image (for use on an electronic
display). What probably matters to the viewer is actually the
angular subtense of each pixel (assuming a digital image), and
the amount of information in the image and the image content.
So in some scenes (studio shots, or with a tripod) it may be
critically important for the angular resolution of the image
pixels to be rather better than the angular resolution of the
eye (so that a sharp image is perceived), whereas for other
scenes (e.g. a soft or out-of-focus effect) providing the
digital pixels cannot be perceived by the eye, less actual
angular resolution is required at the eye.

I print very little as well. My biggest use besides sharing my
pictures on Usenet is running them in slide shows and as a screen
saver just on my monitor. For that, something about at screen
resolution works best for me although over time the size needs to
get bigger and bigger.

I'll take your word for the technical side of perceived image
quality. Again, I have simple needs - it either looks good to me
or it doesn't. Now, when I do print, people who understand that
can immediately see the aliasing but for my purposes, a
borderless 8.5 x 11 generally looks just fine. It is all a matter
of matching needs, wants, and realities.

For what I do print, I find that a sharp 5-6MB image prints
well enough at A4 size (297 x 210mm).

That would be at prevailing wisdom PPIs. None of mine are that
big. I used to shoot at 4 MP and reduce to 1280 x 960 or maybe
1400 x 1050. Now, when I am able to take any pictures at all, I
shoot at 6 MP but save at 1600 x 1200. I don't diss those who
want higher numbers, that is their right.

I do tend to think iamge linear size and pixels rather than
pixels per inch, although I accept that PPI can be a useful
guide as to the number of pixels required for a given size (at
a constant vieweing distance). On the other hand, who views 6
x 4 at the same distance as 20 x 16?

PPI/DPI have always seemed to me to be artificial units which
require a mental gear change so I agree with you. However, if I
talk in terms of just linear pixels or just mega pixels by
extension, I may get flamed.

Your last is quite convincing. I used to pin up letter size
prints on the back wall of my office and Super B (13 x 19) on the
main wall outside my inner office. People used to think they were
photographs not because I am good - I wasn't hardly - but
precisely because they were viewing rather aliased pictures from
far enough away that the defects were not visible at the
subtended angle the eye is capable of resolving.

I also find the entire idea of circles of confusion fascination
exactly for the reasons you cite for mega pixels - namely, it was
developed to be a pragmatic way of judging perceived or apparent
DOF even though mathematically there is only one place truly in
optical focus.

Have a great day, David.

--
HP, aka Jerry

"Efficiency is doing things right, effectiveness is doing the
right things" - Peter Drucker
.

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