Digital BW, The Print

Yes, I am talking about gaps in the histogram which while it may not
always translate into obvious visual degradation, it does represent
degradation.  I've always worked from the premise of "do the least
harm" when doing photography whether optical or digital.  Working in
16 bit gives you the most benefit when dealing with images that have a
compressed dynamic range, like for example an overexposed negative.
Suppose the dynamic range cover only 1/4 of the histogram and we want
to expand it out to a full range image.  Working in 16 bit, we would
have 16384 tonal values to spread out over the resulting 256 tones.
That will give you an incredibly smooth range when resolved down. In
contrast, if you were starting in 8 bit, we'd only have 64 levels to
work with and the result of stretching it out would be a three missing
or interpolated values for every one.

John

> From: mojojones2001 [mailto:mojojones@c...]
>
> I find the difference in working in 16 bit significant when doing
> initial tonal corrections. The extra data allows you to make much
> more tonal shifts without producing gaps. Once I've done that I go to
> 8 bit for all other edits. Now whether or not your capture or output
> device and differentiate that many levels is another story.

Are you talking about gaps in the histogram? Those don't necessarily
translate into anything visible in the image. If there's enough noise or
texture in the image, it will dither across the gap, effectively
filling it
in, as far as the eye is concerned.

I've only seen slight degradation due to 8-bit resolution in blue sky
from a
very quiet low ISO digicam image.

--

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