[filmscanners] RE: 8 bit versus 16

["Austin Franklin" <austin@darkroom.com>]

> > Grayscale only has one channel, and the TOTAL number of bits
> available is
> > only 8 bits per pixel, for 8 bit grayscale.  For color, there are three
> > color channels available, and therefore the TOTAL number of
> bits per pixel
> > is actually TWENTY-FOUR using 8 bit/color pixels, instead of simply 8.
>
> As I said in a post to Robert, if you have sufficient noise (from
> either the
> CCD or film grain) to dither the finer gradations up into the top eight
> bits, then the extra bits buy you nothing. That's equally true of B&W and
> color.

Hi Paul,

I agree with your statement, BUT...I want to emphasize that you really can't
do much tonal manipulation on an 8 bit B&W image without posterization, so I
would have to qualify your statement to exclude tonal manipulations, except
for a very few images.

I agree that 8 bits, with all codes used, will give you an awesome B&W
output with the right printing system, and there is little, if any, to be
gained by higher bit output...but it seems that depends on how you are
outputting.

The Piezo quad-tone driver purportedly adds intermediate tones to smooth the
transitions.  That's my only B&W printing system, so I can't say if it
actually does that or not, and you can't turn it on/off.  I do know that the
Piezo driver is FAR better than the Epson driver though (for the 3000), but
the Epson driver doesn't use quad tones.

But, (yes, another but ;-), some people who use "curves" for quad-tone inks
say they get equal to, or near, Piezo output, and some people who have the
"high bit" Piezo, I believe it was called PiezoPro, say that the extra bits
are noticeable...and that I'm skeptical of, as I haven't seen the same image
printed using the Piezo and then Piezo Pro to see if the tonality is any
"better".

Regards,

Austin

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