Digital BW, The Print

Paul,
That sounds reasonable; I can see how a well-exposed image could look
identical to one with off the bottom 4 of 12 bits chopped off.
Where more bits might be useful, is when heavy manipulations of gamma, etc.
are performed for artistic reasons, or maybe to salvage an image that was
executed poorly.  Not too long ago, a musician that we fancy unexpectedly
walked up to my wife and asked how she liked the show.  I had a few seconds
to fire up the 1Ds and grab a shot.  I screwed up, and the flash did not go
off, opportunity gone.  When I pulled up the raw file, I was shocked that I
could get a very usable image from it.  If the RAW file had 8-bit
resolution, I'll bet the corrections would have posterized it.  Specifically
for BW, ask a leading radiologist to review 8-bit scanned x-ray film; you
will not get a warm response.

This discussion is much like audio, some see it, some don't, some don't
care, but over time improvements _are_ made.  Twenty years ago, who would
have thought that printing to paper could benefit from more than 256 levels;
but we are making those evaluations now, with some acceptance that it
matters.

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Paul D.
DeRocco
Sent: Sunday, July 03, 2005 9:23 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: RE: [Digital BW] Artifacts with Digital images

> From: Steve Kale
>
> As a point of clarification, I believe what concerns the user most is the
> usable dynamic range delivered by the camera - not the dynamic
> range of the
> sensor ignoring all other aspects.  I have always found it puzzling that
> Canon has not moved to delivering the user 16 bits and had always assumed
> that the issue was processing speed.

<snip>

> The question that concerns my original post is whether or not, all
> else being equal, an increase in bit depth provides greater usable dynamic
> range to the user.

It won't. The extra bits will be utter garbage.

I did some rigorous tests on my old Minolta DiMage 7 camera, which has an
uncompressed raw format, making it easy to manipulate in software. Its
sensor, under the best (broad daylight) conditions has eight bits of dynamic
range, because masking off the bottom four (out of 12) bits of the raw data
made absolutely no visible difference in the image. I'd say that my Canon
10D has about ten bits, based on the ratio of noise levels, so increasing
the A/D resolution beyond 12 bits would be useless. And if 12 bits is two
more than necessary in the 10D, I doubt there are any DSLRs out there yet
that really need more than 12.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...




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