When you calibrate your workflow for digital negatives you do three things:
1. find your maximum black - it's your standard printing time - lets call this 100%. No need to use a longer exposure time, it never gets blacker!
2. find the right color (or a combination of ink laydown % and color) to get minimum white - lets call this 0% No need to block more than needed to get paper white.
3. linearize between these fixed 0 and 100% bij making a correction curve
As 1 never can get darker and 2 never gets whiter and they correspond with the 0 and 100% patches in your original greyscale you can safely set them to 0 and 100 after scanning. Take care to scan all image information and prevent clipping or curve changing. Set white and black points just outside the histogram in your scan preview and scan linear (no whitebalance or other curve correction by the scansoftware).
On 16 jun 2008, at 13:56, Yves Gauvreau wrote: