Digital BW, The Print

Walt,

> ... Epson actually does recommend a DG20 gray
> space.  ... U.S. Prepress Defaults, which is an RGB
> space of Adobe RGB (1998) and a gray space of Dot Gain 20%...

Similarly, in Elements the color space that uses DG 20% is said to be
optimized for printing.  However, the GG 2.2 is the default that most are
going to be seeing from their digital cameras and on the web.  I think the 2
spaces make good alternative approaches.


> ...I used the Gamma 2.2 workspace but the "light" setting in the driver
> because I got better ICC profiles.  ... The reason for my
> doing this is that the *unmanaged* targets printed for ICC profiles
> reflect exactly the compression we'd expect of GG 2.2.  In the
> shadows, the closeness of the patches is more difficult for the
> spectro to discriminate.

I've come to basically the same conclusion.  On the R220 setup I am tuning
for, among other things, ICC printing, I make sure there is enough shadow
separation for a reliable, relatively consistent print.

>  In some recent tests with Paul (in which we
> measured our own targets five times and then each others, each with a
> different instrument and in my case in both patch and strip mode)
> variations on the order of L* 0.5 were quite common, and I showed one
> as high as L* 0.88.

It's important to note that most of this variance is in the print, not the
instruments.  


>  Thus the target from the light setting makes
> these errors much less significant and provides more reliable data as
> a basis for the ICC profile generation.  Having better resolution of
> the data at this level and then recompressing the 85-100 K for visual
> correctness is, I think, more reliable.

The flip side of this is that with more compression, more information is
lost.  So, I want enough shadow separation for reliable reading, but not
much more.  

>  So, the issue is not that
> the target doesn't "look right," it is that the "darker" target is
> more difficult to reliably read.  Incidentally, we both found that
> the variations from the printer (target to target, printed
> consecutively) were greater on my 4800 and Paul's 180 (?) than were
> the variations in spectro reads.

I used the R220 with the still-not-released MIS inkset for it.

Paul
www.PaulRoark.com