Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@y..., "Austin Franklin" 
<darkroom@i...> wrote:
> 
> > Hi Austin,
> >
> > Here is the URL that will get you to the spec sheet for the 
scanner:
> >
> > http://www.dimage.minolta.com/
> >
> > Be sure to have your magnifying glass ready! Some idiot set the 
whole
> > thing in 4 or 6-point type. Talk about trying to read the fine 
print!
> >
> > I share you skepticism on this one. Is it perhaps a numbers game
> > where the 16-bit A/D converter cost very little but let's them 
make
> > more outrageous claims?
> >
> > Martin
> 
> I believe they are not being honest here, or just plain don't know 
what they
> are talking about.  There is a little link to a URL that shows 14 
bit vs 16
> bit.  It claims 16 bits "resolves the image with greater 
fidelity...".  That
> is a physically impossibility.  First off, the shadow detail they 
show is
> not near real shadow detail!  It's mid range detail.
> 
> They also claim "ideally suited for...16-bit compatible software 
such as
> Adobe Photoshop"...  And as I said, if you are getting a full range 
of 16
> bit data, you can NOT do any level shifts to it in PS without 
losing data.
> 
> I believe the curve they show is erroneous.  All, both 16 and 14 bit
> values/steps, would be in the MIDDLE of the curve, and they 
wouldn't be
> steps, they would be dots.  Pixel depth doesn't have "steps", they 
are ratio
> values and more bits just give you larger numbers, the "steps" 
between the
> numbers is exactly the same.  Steps happen with PPI, NOT with pixel 
depth.
> This is very very misleading.
> 
> Click on "16-bit A/D..." on the Pro page, then click on "16-bit vs.
> 14-bit...".  Take a look and see if you agree.  This really irks 
me.  I
> believe it's totally outrageous.

Austin,

Don't you just love graphs that have no labels on the axis not to 
mention no units. Wouldn't want to confuse the poor consumer with too 
much information.

The only way I can look at it that might make sense is if the x-axis 
is distance across the image and the y-axis is a varying intensity of 
the R channel. Given that if you go from 0 to 100% intensity 14-bit 
would represent that with 16,384 levels and 16-bit would use 65,536, 
but we cannot distinguish between 16,384 shades of red or gray much 
less 65,536 nor can the film, so it all seems meaningless to the end 
result.

There is a relationship between bit depth and the noise floor if I 
understand it correctly. I did notice in comparing 12-bit to 14-bit 
RGB slide scans on a Polaroid SprintScan 4000 to a SprintScan 120 
that there was a decrease in noise in dark portions of the slides. 
This was an improvement but not an overwhelming one. With B&W 
negative scans from the two I don't see any noticeable difference in 
the final prints.

Assuming you did go to 16 or 18-bits in a 24-bit or larger space 
would you see a significant reduction in noise or is it a case of 
getting smaller and smaller improvements with each increase in bit 
depth?

Looking at three factors in a scanner, optical path sharpness, pixels 
per inch and bit depth, which is going to be the biggest contributor 
to a good scan? Assuming that all three are at a least an adequate 
level, which one would you be most interested in improving first, 
then second?

Martin