Digital BW, The Print

Hi Ernst,

> Some consider 3 as the highest possible with CCD
> scanners.

Well, I KNOW that simply is not correct, as I've designed CCD scanners that
have far more than a density range of 3, and they have been thoroughly
tested to prove so.

> That's where PMT drum scanners are superior, the range is wider / noise
> further away. So analoge gain can then be used without the
> penalty of noise.

To some degree true, but the superiority of PMT scanners is they don't
suffer the bloom and smear characteristics of CCDs.

Analog gain can readily be used with CCD scanners, it depends on the design
of the scanner.

> I have followed the thread on what the eye still can see of tonal
> steps in a
> piezoprint.

I was not referring to only a "piezoprint", but any grayscale image.

> I can't judge that part by experience with piezo
> printing though
> I doubt the eye is limited to 256 steps.

Actually, it's quite a well proven/known fact that the human eye is limited
to being able to discern between 100-200 graytones.  NOT colors, but
graytones.  Do a web search and you'll find many many many references to
this, with decent substantiation.  You can search the archives of this group
as well, as it's been discussed here.

> There's something that
> is added by
> a real smoothness of tones that probably can't be explained by the eye's
> capacity to distinguish tones and resolution.

Understood, and agreed.

Regards,

Austin