Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul D. 
DeRocco" <pderocco@i...> wrote:
> > From: Glenn Mitchell [mailto:gmitchel850@y...]
> > 
> > Noise becomes more apparent because of the effects of 
posterization 
> > as you edit the image.
> > 
> > Chromatic noise which is barely noticeable when the image is 
loaded, 
> > for example, can be quite obvious as clumping or graininess 
after 
> > levels adjustments, curves adjustments, hue/saturation 
adjustments 
> > precisely because you are selectively expanding some information 
and 
> > selectively compressing other information. What starts out as 
> > continuous or near-continuous tones becomes less so. This effect 
> > will be more exaggerated with an 8-bit image than a 16-bit image.
> 
> Sure, but at least you won't see outright banding.
> 

That's not necessarily true at all.

Noise comes in varying degrees. It's effects on an image are not 
always uniform.

Luminosity noise is often speckled about. But chromatic noise often 
affects sky, shadows, water and is less/non-evident elsewhere in an 
image.

Noise is a separate issue from posterization owing to nonlinear 
transformations during image editing.

There is no reason to expect noisy images from a digicam to 
obliterate all evidence of posterization.

Cheers,

Mitch