Dan's "Black Hole" image

Dan Margulis <76270.1033@...>

Ron writes,

I finally got a chance to see the digital photo of the "black hole" that
appears in Professional Photoshop 6. Interestingly, the "before" version
did *not* print as solid black-- if I hold the book at an angle to the
light (to avoid glare), I can actually see most of the detail that shows up
in the "after" version. It's very dark, but it's there.>>

Well, *something* has to be there; even I can't fix an image that's 0,0,0
throughout. But I thought that the result when the range was opened up was
astonishing. I expected it to be full of noise. In fact, the result was a
lot better than one would get with a drum scan of a similarly dark piece of
a film--the scanner would have latched onto the film grain.

That particular image really should give pause to people who are obsessed
with extra bits. It's quality, not quantity, of data, that counts. That
corrected image can be expressed in 5 bits per channel.

Could the original have been improved by using a longer exposure?
(And maybe a tripod to keep the camera steady?)>>

Certainly, but that wasn't the point of the exercise, which was to get
something nearly hopelessly black and see what was actually there.

I'd like to see reviews of digital cameras (either in print or on
the web) that use images as challenging as this one.>>

Good luck. First of all, the technology is improving so rapidly that almost
any review is obsolete by the time it appears. Second, you don't often see
reviews of either cameras or scanners written by people who are
particularly knowledgeable about the subject. Third, few if any reviewers
see these cheap digitals as the revolution that they are, and the rest
insist on comparing them to previous film-based products.

Dan Margulis

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