[filmscanners] Re: Pixels and Prints

["David J. Littleboy" <davidjl@gol.com>]

"Arthur Entlich" <artistic-1@shaw.ca> writes:
>>>>>>>>>>
>There is a question as to how much more
> information a 5080 dpi scanner gets out of a 35mm frame than a 4000 dpi
> scanner. I suspect that it's not enough of a difference to be significant.

I think this is probably true, due to the "cutoff" of the human eye and
brain.  Basically, for the size of prints most people produce, there
probably isn't much to be gained by going above 4000 ppi scans, although
I can see what's missing in a 4000 ppi scan versus the original image
looked over with a loupe.
<<<<<<<<<<<<

I've seen photomicrographs of Velvia and Kodachrome 25 that show a lot more
than what a 4000 dpi scan gets. However, it's usually extremely high
contrast subject matter (like test charts<g>), and the grain is seriously
ugly. It doesn't look (to me) as though that information is useful for
pictorial photography. It might be useful for special effects and spying, I
suppose. If you look at MTF charts, film begins to lose contrast pretty
rapidly above 20 lp/mm and the contrast is way down at 40 lp/mm. Trying to
get useful mileage out of such low contrast seems pretty hopeless.

>>>>>>>>>>>>>>
However, I'd like to see what happens with a four foot wide poster print
from a 35mm film scan (with a drum scanner) and a 9 MP digital image.

The problem with the digicam image is that at the point that pixels
become visible, then our eye starts to object due to the recognizable
sharp and gridlike pixel edges.
<<<<<<<<<<<<<<

There's no need to display pixels as squares at large sizes. Most digital
images are taken through an antialiasing filter, and don't depend critically
on individual pixels; that is, the highest frequency represented is usually
70% or so of the Nyquist frequency. So the area between pixels can be
smoothed (blurred) by up to the pixel radius (if not more) with no loss of
information, and no apparent pixelation, whatever size you print at.

And dSLR images at ISO 100 are noise free. No grain, no pixels, no noise.

>>>>>>>>>>>>
  At that point, film grain (dye clouds)
becomes more acceptable, because it is analog (random placement, size
and overlap) which our eyes find more pleasing.
<<<<<<<<<<<

If you meander by the West exit of Shinjuku station here in Tokyo, you can
see an 8 foot by 16 foot backlit mural. The grain's seriously ugly if you
get close, but pictures that large are seriously cool, no matter how ugly.
Inversely, there are occasionnal 30x40 advertising posters in the train
stations that are clean and sharp even with my built-in 8x loupes (I'm
grossly nearsighted and an incorrigible grain sniffer).

I can't really speak to posters and murals. I don't like prints in the 16x20
to 30x40 range that I can't walk up to, so I wouldn't try to print any of
the 645 I've done (Mamiya + Nikon 8000) at much over 12x16, 13x19 at most.

But it sounds as though everyone who has ever printed a digital image at a
riduculously large size has been extremely happy with the results, so I
suspect that your intuition here is dead wrong. I suspect that the reason
people are happy with large digital prints is that there's no noise/grain
whatsoever. (I'd probably find it seriously irritating that there wasn't any
detail to be seen, but that's me.)

>>>>>>
 Our world is full of
analog visual "noise", even our eyes produce it, so we learn to ignore
it, but sharp edged square cornered patches of color are pretty obvious
to us.  It is the reason camouflage works so well, our eyes and brain
don't register ill-defined edges of similar colors well.
<<<<<<<

Again, there's no reason to see pixels in larger digital images at all.

David J. Littleboy
davidjl@gol.com
Tokyo, Japan

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