QTR-Quadtone RIP

On Dec 30, 2007 2:00 AM, ferdinand_paris <ferdinand_paris@...> wrote:

> --- In QuadtoneRIP@yahoogroups.com, "Eric Neilsen" <e.neilsen2@...> wrote:
> > And now that Mike has released v200, all your tests may change with
> > the next upgrade. Darn frustrating : (
>
> At the risk of someone thinking that I've become obsessive about this,
> I did indeed rerun these tests.  Qimage 2008.200 results are at:
>
>   http://www.ferdinand-paris.com/BPC-Qimage_V3.png
>
> The only one that has changed compared to my V2 histograms from
> 2008.109 is converting to a generic profile in Qimage without BPC,
> which now has a very large amount of black point clipping.  I don't
> recall seeing any CM changes flagged in the release notes.
>
> So now there is some reverse symmetry.  If you convert to a generic
> QTR profile in Qimage, you *must* use BPC or else you will see a lot
> of shadow blocking.  On the other hand if you convert to a custom
> profile (or at least mine), then you should *not* use BPC or else you
> will get a big dMax loss.
>
> Go figure!
>
> F_P
>
>

I've got a new version of Create-ICC that might help in this.

Download:    http://www.quadtonerip.com/QTR-Create-ICC-BPC.exe


This maps black to black on both directions of the profile.  What this gives
up

is soft-proofing with Simulate Ink Black.  The benefit though is my tests
with

Photoshop show identical results for all combinations of Perceptual &
Relative

Intent and BPB on or off and with different CMSs on the Mac.


I'm interested in any findings you guys get.   I highly recommend using a
21step

wedge to do this.  Cut out just the steps so you have a perfect comb in the
histogram.

Then you can see if the results are the same.  (+/- 1 level is OK).  With PS
I used 16bit

and the histo-results were 100% identical.  I'd also go with a simple made
up custom

profile such as "20 96"  which shows significant movement in the histo.


Roy


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