Bob Wright wrote:
> Al, how have you concluded that the Scan Elite
> software does all its calculations on 8 bit data?
I did two scans of the same slide. With the first, I went to the
levels tool in the driver software and adjusted the midtone (gamma)
from 1 to 1.5. I then scanned in 16 bit mode. With the second scan,
I made no adjustments in the driver software but scanned in 16 bit
mode into Photoshop and then made the same levels adjustment there.
When the histograms for both scans are viewed in Photoshop, there is
a big difference: the scan manipulated by the driver software has
serious gaps at regular intervals in the histogram. The Photoshop
manipulated histogram remained smooth.
>From what others on the list more experienced then me have said, this
is indicative of 8bit manipulation and rounding errors. (I guess I
should have tried changing the mode in Photoshop to 8 bit and then
doing the manipulation: in theory the histogram for that should then
look identical to driver manipulated scan.)
Al Bond
