Re: Why?

[Kees Brandenburg <ctb@zeelandnet.nl>]

Hello Yves,

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).

regards

-kees




On 16 jun 2008, at 13:56, Yves Gauvreau wrote:

> Hi all,
>
> I'm intrigue, I've been reading about color management for a while  
> now and I
> can't help myself asking why most method of creating digital negs  
> suggest to
> strech the scan of the 101 stepwedge print or equivalent from 0 to  
> 255 while
> every mapping algorithm I've seen so far basically say that the  
> opposite is
> the norm?
>
> Have a nice day,
> Yves