U of S | Mailing List Archive | alt-photo-process-l | Re: venetian blinds, Epson 1280 and other printers

Re: venetian blinds, Epson 1280 and other printers

The RIP made a slightly colorized RGB negative (Green=4) behave perfectly. It is close to linear right out of the box. I have fashioned a correction curve for it, but it is very subtle, and maybe unnecessary.

 I am going to print your arrays today and see what I get. I noticed the same weird behavior when I sampled a few rows in the array with the UV densitometer. Humps is a great word for it.


On Mar 4, 2007, at 12:28 AM, Michael Koch-Schulte wrote:

Clay,
If you have a closer look at the printout of my arrays at hybridphoto you can see that there are "fingers", "shadows" and "hot spots" of density all over the place, not just in the red-green range (although I think they're more pronounced there). Far from clean and/or linear. So, choosing the starting colour strictly based on numbers without paying heed to this knowledge means there's at least the possibility you're going to have a hump in your curve where you didn't expect it, at least with the Epson driver. It's kind of like going for a hike (in the mountains) using a political map thinking everything is flat and two dimensional when really what you need is a topographical map. Not a big deal because a curve can fix this, just a little disconcerting and annoying. The solution would be to either pick another starting colour that avoids running over one of these blips or charting another "direction" of desaturation through the colour model, somewhere where it's all downhill. I'm interested in finding out what you find out with the RIP. Does it exhibit the same anomalies?
 
~m
----- Original Message -----
From: Clay
Sent: Saturday, March 03, 2007 9:53 PM
Subject: Re: venetian blinds, Epson 1280 and other printers

I'm just about through getting a 7800 calibrated using the Imageprint RIP.  It is a bit premature to claim victory, but early indications are showing the following benefits:

1) the dithering pattern, when examined with a loupe, is both finer and smoother, and to my eye, sharper than that generated by the Epson driver. 
2) highlights are beautiful - subtle in a way I have only heretofore seen with in-camera negatives.
3) The prepackaged profiles for Pictorico make it possible to print a decent palladium negative by simply inverting the file and printing it!!!!
4) Fine tuning the output takes a very small correction curve, if you even care to bother. 
5) RGB space is the way to go, along with some subtle colorization.
6) The RIP takes full 16 bit input. So you can stay in 16 bit mode through the whole process, including the printing step.
7) Using roll media, you can tile many negatives on a single print job and save a lot of wasted pictorico.

Weird things about the 7800:

The straight-ahead PDN system does some extremely strange things when you use the standard Epson driver and colorize the negative. For instance, the spectral tests I ran indicated that a Red 200, Green 25 blend would be ideal for palladium. Using the PDN test tablet, here are the UV densities for the first couple of highlight steps:

Step 100:  2.03 logD UV
Step 93:  2.07
Step 91: 2.6 !!
Step 90: 2.85!!
Step 89: 3.17
Step 88: 3.24
Step 87: 3.52!!
Step 85: 2.93
Step 84: 2.68

Now this is just plain weird. 

Visually, the steps appear to be getting less dense as you move down to lower step numbers. But my UV densitometer tells another tale. And I confirmed this by printing the negative again AND deliberately overprinting the step tablet by a stop  to see if I could even get any tone in those strange steps in the middle. It tells the same story. So a correction curve using this PDN color would be very difficult if not impossible to make with these density reversals in a gradated step wedge what in theory is the same tone. 

More later.

Clay



On Mar 3, 2007, at 7:36 PM, Ender100@aol.com wrote:

Hi Don,

You can use a RIP with PDN—though once I noticed a strange repeating pattern in a print made from a negative off a RIP.  As you mentioned, there seems to be no free lunch.  It is a matter of finding a combination with the least problems.  Though I must say, other than the Venetian Blinds, which I solved by getting an R1800, I have very little problem making good negatives.

Mark
In a message dated 3/3/07 7:10:10 PM, dsbryant@bellsouth.net writes:



Thanks Mark. Seems like there is no free lunch with ink jet printers, we are always chasing one problem or another. I wonder if a RIP could solve some of the ink density problems. I think Clay Harmon is working with IJC/OPM and the 7800. Could a RIP be used with PDN ?

 

Don







Best Wishes,
Mark Nelson

Precision Digital Negatives - The System
PDNPrint Forum at Yahoo Groups
www.MarkINelsonPhoto.com






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