Digital BW, The Print

Recently, Dan has specifically mentioned the advantages of using 16-bit
when using Photoshop's Shadow/Highlight commands. In my work I prepare lots
of color images for B/W offset printing, usually to be done on poor paper
(newsprint and cheap uncoated) where controlling ink is an important issue.
I have found that judicious use of the S/H commands in 16-bit can rescue
problem images. The results are much smoother than when using 8-bit. It
even pays to convert from 8 to 16 just for S/H, and then immediately back
to 8 for other manipulations.

BTW, the fifth edition of Margulis's Professional Photoshop, is out or will
be very soon. Official publication date is Dec. 7, but it will be in stores
before that, according to a post of his on his Color Theory list in late
October. Amazon has it listed as arriving Nov. 22. Dan promises the fifth
edition is the last one he will do; he's announced he's retiring from all
but a few teaching gigs as of early next year.

jonathan wills
_______
wills design
portland, oregon, usa

At 10:09 AM +0000 11/14/06, Olivier wrote:
>Most of the people here have probably heard about Dan's 16v8b
challenge and know that till now no one has really proven 16b is
superior. But this is mainly due to Dan's initial assumptions namely
a sRGB working space for the file to be output on press, and he can
not be wrong in this case. For those of you who follows this, this
paper can be of interest :
<http://www.media.hut.fi/~as75192/tenttima/Ext_gamut.pdf#search>http://www.media.hut.fi/~as75192/tenttima/Ext_gamut.pdf#search
>This tends to prove 8 bits suffice in this configuration. Recently
Dan admitted for wide-gamut color printing that some images benefit a
larger space, and the debate can rage again.
>Now Dan has also always mentionned that correcting a greyscale file
might call for 16bit for you do not get so many codes to describe
shades and gamma 2.2 spaces might be best suited.
>In the case of a scanner the 16b advantage is else : say your scanner
is capable of real Dmax 4 (log 10,000 ; 10), then to encode that Dmax
in bit you need puissance 4^2 hence 16b. So theoretically 8bit gives
you Dmax 3 ; theoretically because 1 bit encodes whatever Dmax you
want, but here we assume the bits are perfectly distributed, plus
some get lost in noise.
>Yet both Tyler and Roy demonstrated that this is a pointless
discussion when you have the print in hands : so you might benefit
from a 16b correcting process, but nothing proves AOT the printing
will benefit from a 16b file feeding. If I'm not wrong Krawitz turned
Gutenprint in a 16b driver but not for the sole encoding of the
values, but also to encode variable drop size, ink position, ect...at
the end of the dithering not so many bits are devoted to the values
themselves.

Olivier


-- 

jonathan wills
_______
wills design
portland, oregon, usa