Digital BW, The Print

>
>He knows histograms, and he knows the math, he knows tones get dropped. He
>feels between output screening methods, the limited ability of humans to
>differentiate anywhere near 256 tones, the amount of colors that can be
>combined from as few as say 50 tones in each channel, etc, add up to
>deteriorated 8-bit images that might look *slightly* different than their
>16-bit counterparts, but not necessarily worse, and sometimes better.

I can't help wondering if there's a corollary here to digital audio, 
if I can drift off-topic. The standard CD format, unchanged since 
1980 or so, is 16 bit, 44 Khz sampling rate. One can easily 
demonstrate mathematically (Nyquist, etc.) that this standard 
provides complete reproduction of the audible spectrum and dynamic 
range. It was actually introduced under the banner of "Perfect Sound 
Forever".

Problem was (and is) that the 16/44 CD never sounded as "good" as 
analog tape (or the venerable LP) in a high resolution audio system. 
The decimation, data jitter, and aliasing problems become easily 
audible. Audiophiles know this, but the average consumer is happy 
with their boombox and automobile playback. The insanely popular MP3 
format uses heavy compression of CD quality digital and throws away 
scads of data, but most listeners never notice.

There are now two "high-bit" audio formats being introduced that 
exploit the greater capacity of the DVD format. DVD-Audio is 24 bit, 
96Khz, and SACD is a 1 bit, ultra high sampling system that 
esentially mimics analog. The improvement with either is instantly 
heard as a more "natural" presentation, not as more volume, detail, 
or violins. Few consumers have ever seen one of these discs, let 
alone heard one. This despite the fact that most recording today is 
actually mastered at 20-24 bit resolution (often from analog session 
tapes). The high resolution recording is instead dumped to 16 bit for 
release. Because the market for a "better than good enough" product 
is minescule, the record companies have little incentive to release 
titles in the high-bit format, despite the fact the superior original 
sits in their vaults.

I suspect Adobe's perspective on bit depth is similar. The standard 
was based on what was possible 5 or 10 years ago. As a pre-press 
application, 8 bit is fine for the vast majority of users. The fact 
that today's scanners can provide 12, 14, or 16 bit data seems 
largely wasted. Yes, it permits more extensive manipulation without 
artifacts, but 16 bit may make no other difference in offset printing 
or web publishing.

I come to digital from a photographic background. The 8x10 AZO in 
Amidol contact print is a standard I'm familiar with. (So's the 12x20 
contact, but that's a bit much:-). Kodachrome 25, Ektar 25, platinum 
prints, Leica, Nikon, Schneider and Goerz glass, Tech Pan and Gigabit 
film. Ciba developed in Beers. I've even made a dye transfer print 
(once was enough!). I have high photographic standards. I like what I 
see from digital ink-jet printing, but my references have not been 
eclipsed. I'll be pleased when they are, because I don't want to rely 
on 19th century technology indefinitely.The few people (like myself) 
concerned with working directly with photographic images may not see 
the true benefit of 16 bit scans until "continuous tone" 16 bit 
printer technologies emerge. Or a hot-rod version of PS that 
streamlines the workflow and options for photographic output rather 
than print or web. And because I'm sure such products will eventually 
materialize, I will scan at the highest qualities I can, and archive 
the raw scans along with the negatives. For the same reason I kept my 
LPs.




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