QTR-Quadtone RIP

I've been struggling to understand how to create an ink descriptor file (profile) for OHP. I'm making negatives for alt process (pt/pd) printing. I have samples for a 3880, and I know how to make and measure the linearization curve in photoshop, but I'm stuck on creating the "no curve" profile. Can anyone point me to one? Thanks!

All (that I’m aware of) current pt/pd workflows currently require some (curve/level) adjustment in Photoshop (or the like) to correct for basic contrast variables introduced by specific chemistry choices during the printing process after one has figured out the basic contrast ratio issues (dmax/dmin). (I guess you could apply a photoshop curve as linearization data to the bottom of a QTR descriptor? Is that what you are talking about?)

I’m new to this but have been working very hard on some really interesting mathematical algorithms recently re: this very problem. I can’t go into detail but I guess I would say stay tuned. If it works it works.

//

There are a few really amazing resources out there. Ron Reeder is one, Mark Nelson another, and Jon Cone’s system (full disclosure I work for/with him now) of course.

Ron’s book on the digital negative and platinum printing is a great read and worth a start. (http://www.ronreeder.com/a-new-book-on-qtr <http://www.ronreeder.com/a-new-book-on-qtr>) Nelson’s curve system is another incredible and in-depth and genius take on it all using color inks mixed with zone-system brain power (http://www.precisiondigitalnegatives.com/ <http://www.precisiondigitalnegatives.com/>) and automated photoshop curves, and Jon’s inks are truly in sync with all of it essentially . . . we are all kinda nuts about this stuff. Dunno if it’s that sane but hey.

regards,
Walker
R&D @ InkjetMall

> On Jan 29, 2016, at 7:03 PM, Roy Harrington roy@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
> 
> 
> No sure what you want for a "no curve" profile.
> There are several people who do negs and you ought to follow one of their workflows.
> See www.ronreeder.com <http://www.ronreeder.com/> for example.
> 
> Roy
> 
> 
> On Thu, Jan 28, 2016 at 10:21 PM, kayeffdubphoto@... <mailto:kayeffdubphoto@...> [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com <mailto:QuadtoneRIP@yahoogroups.com>> wrote:
> 
> 
> I've been struggling to understand how to create an ink descriptor file (profile) for OHP.  I'm making negatives for alt process (pt/pd) printing.  I have samples for a 3880, and I know how to make and measure the linearization curve in photoshop, but I'm stuck on creating the "no curve" profile.  Can anyone point me to one?  Thanks!
> 
> 
> 
> 
> 
> 
> -- 
> Roy Harrington
> roy@... <mailto:roy@...>
> www.harrington.com <http://www.harrington.com/>
> 
>

I can share that with you. I have not too long ago switched from a 3800 to a 3880, but I still have 3800 profiles. It will be easy if you are using a Mac, an extra step or 2 if you are on Windoze. 

One thing you should be aware of, and the reason that sharing profiles is not as easy as you might expect, is that there are a lot of personal variables in Pt/Pd printing and each profile assumes a particular set of variables. Changing paper or developer, or the coating mix will likely require reproofing to get optimum results. 

This list doesn’t allow attachments so I can send you the file directly if you’d like, or you can copy and paste the following into a text file. 


#Notes Profile for Pd with 1 drop 2.5% Na2Pt per 2ml developed in KOx at 120° 
#Notes (or equivalent such as Pd developed in KOx #1 NaDichromate) on Arches Platine.

PRINTER=Quad3800
CURVE_NAME=3800pK-POHP-BL-Pd-4
GRAPH_CURVE=YES

N_OF_INKS=8
DEFAULT_INK_LIMIT=60

BOOST_K=60
LIMIT_K=50
LIMIT_C=5
LIMIT_M=5
LIMIT_Y=12
LIMIT_LC=5
LIMIT_LM=5
LIMIT_LK=60
LIMIT_LLK=80

N_OF_GRAY_PARTS=3

GRAY_INK_1=K
GRAY_VAL_1=100

GRAY_INK_2=LK
GRAY_VAL_2=40

GRAY_INK_3=LLK
GRAY_VAL_3=10

GRAY_HIGHLIGHT=2
GRAY_SHADOW=6
GRAY_OVERLAP=

GRAY_GAMMA=1

GRAY_CURVE=“0;0 100;100”

N_OF_UNUSED=0
COPY_CURVE_C=K
COPY_CURVE_M=K
COPY_CURVE_Y=K
COPY_CURVE_LC=LK
COPY_CURVE_LM=LK


One thing I’d like to note is that since switching to the 3880, I have been making use of the GRAY_GAMMA field, which previously I had left set at the default setting of 1. Going off something I remembered Clay Harmon mentioning a while back, I experimented a bit with changing gray gamma to 0.9, 0.8, 0.7, and 0.6 which I then plotted and compared. I found 0.8 and 0.7 to be very useful, making the correction curve even gentler than it already was. If you want to use this, simply the 1 to 0.8 or 0.7 in the GRAY_GAMMA field. 

I have also gotten away from linking the GRAY_CURVE field to an external file, and prefer instead to enter the curve points directly. It just makes keeping track of things a little easier.

Hope this works for you,
Keith

Keith Schreiber
jkschreiber.com

> On Jan 28, 2016, at 11:21 PM, kayeffdubphoto@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
> 
> 
> I've been struggling to understand how to create an ink descriptor file (profile) for OHP.  I'm making negatives for alt process (pt/pd) printing.  I have samples for a 3880, and I know how to make and measure the linearization curve in photoshop, but I'm stuck on creating the "no curve" profile.  Can anyone point me to one?  Thanks!
> 
> 
>