Piezography Digital Negative meets Mark Nelson's Precision Digital Negative (PDN optional not required)
28 March, 2011 by
Piezography Digital Negative meets Mark Nelson's Precision Digital Negative (PDN optional not required)
Jon Cone

UPDATE: Piezography Digital Negative has taken a GIANT leap forward and is now called PiezoDN. Read more about it here: https://piezography.com/piezodn/about-piezodn/


By marrying Precision Digital Negative system to the Piezography Digital Negative process, one is able to eliminate dithering, increase the output resolution, and have a personal method to linearize silver print or any alternative process. The Piezography Selenium inks and QTR curves are an enhancement to PDN.

I redesigned a whole new QTR curves architecture that is compatible with the linearization portion of PDN. I ended up with something that I feel really satisfied with. Making silver prints will be easier for Piezography Digital Negative users, and in many ways a lot of fun.

Do not let me confuse you. PDN can not make QTR curves. If your QTR curve is not already perfectly linearized for film (meaning you tried to make your own and got something lumpy), PDN can not correct that. You will need Piezography made QTR curves to work with PDN. But at $50, PDN is an inexpensive add-on to the Piezography Digital Negative System that brings a whole new level of creativity.

What PDN does is correct your Photoshop images so that it prints in a linear fashion with your choice of alt process. No matter what type of humidity condition you experience, or your hand coating method…PDN can correct for that. Because Piezography Digital Negative are not subject to variations in humidity and hand-coating techniques, very little PDN intervention will be mandatory. But, each different type of silver paper has its own characteristics and PDN can be used with Piezography Digital Negative to linearize the silver print process using just the “Curve Calculator” portion of PDN.

By replacing the color inks portion of PDN with Piezography inks, digital negative makers will find the PDN process significantly easier to use and the results will be worthy of fine silver printing.

Mark Nelson writes in his manual “There are two features of digital negatives that are often referred to when comparing them to analogue negatives or in–camera negatives. The first is the ability to render smooth tonal transitions and the second is the ability to render detail. Basically, I’m talking about holding a print in your hand and viewing it at reading distance—not examining the print with a microscope. I have shown prints to people and once mentioning that they were made with digital negatives, they would look at them more closely and suddenly “discover” that they see something “digital going on.” I think had I not told them that the negatives were of digital origins they would not have either seen or imagined anything digital. But then, I’m over forty years old and way beyond my first pair of reading glasses.”

Many alternative processes can be viewed at “arms length” and the color ink will make satisfactory films for printmakers. But, fine darkroom silver printing has never really been about looking at a reading distance. At some point, the viewer looks at detail and digital artifacting is not something that many darkroom printers will want to aspire to. This is what Piezography Digital Negative brings to Precision Digital Negative. It allows the PDN system to be used for high standard digital negatives, and it makes the PDN system much easier to use by eliminating several of the steps.

And in order to preserve the full dynamic range of a Photoshop image in 8 or 16 bits, I produced a family of QTR curves that produce a specific range of densities that are designed to match the needs of the user’s individual alt process. The user does not need to compress the image data in order to print at the correct density range. Instead, they choose the correct Piezography QTR curve. I eliminated the use of Piezography shade 1 black in favor of Piezography shade 2 very very dark gray.

For example, I can get a full range of tone from Ilford RC paper by using a negative that has a dynamic range of 0.10 to 1.50. So I use a QTR Curve that only produces a maximum density of 1.50. For Ilford Fiber Base, I can use slightly more density, and I now produce Curves that produce density ranges such as 1.40, 1.50, 1.60, etc. These are all perfectly linearized for Pictorio Ultra OHP film.

So an interesting synergy between PDN and Piezography is achieved and an interesting balance now served that lets me concentrate my development time on adapting the new curves to the full range of supported printers.

The interesting thing about using Nelson’s PDN system with Piezography inks is that it only requires the use of the Curve Generator portion. Three time consuming steps are eliminated. The user simply prints out the 21 step inkjet target onto film by selecting the correct Piezography QTR curve and combination of Piezography Selenium shades. The film is exposed and processed as a silver print, and the 21 steps measured by densitometer (or converted Lab). The density measurements are now entered into the PDN Tonal Palette which generates and exports a linearization curve for Photoshop that is used to correct an image before it is printed with the same process.

It is very simple and elegant – and the results (especially when contrast linearizations are added) look decidedly photographic.

I have a method for establishing the correct exposure time that differs from the PDN method and does not require the purchase of a Stouffer strip. Because I have already linearized the inks output onto Pictorico film, the user needs only print the target, expose the paper, and develop the process. Then the final measurement of the printed results is used by PDN to generate a correction curve for Photoshop if needed. The PDN user is able to skip all the tedious portions of PDN and go right to the creative portions of PDN.

Because the Piezography system is based on density rather than UV absorption via color inks, the need to recalibrate is greatly reduced. So instead of the PDN system being used daily to make alt process corrections, it becomes an amazing creativity system for use with Piezography Digital Negatives (or Positives). It is likely, that a single PDN curve may only need to be generated for silver print. And this can be used over a long period of time. But, for alternative process that is subject to humidity and hand-coating of emulsions, the PDN system may need to be used more often (although being density based should not be needed to the same degree it would when using color inks.) We will need to hear more from alt-process users. I can only speak with confidence about silver printing.

Now the really cool thing about the PDN system is that it generates an endless variety of contrast curves for Photoshop. The image is simultaneously linearized in relation to the contrast curve that is applied. I think that that is the sweet spot of the process.

It results in endless creativity. One can even use PDN to create hybrid curves from the best part of two curves. I had a great time in the darkroom with it. I saved these curves in Photoshop and applied them to images as I needed. PDN makes images that retain the toe and shoulder of traditional darkroom printing. The sublime Gamma 2.2 of the Piezography film, though part of the film process, gets converted to the PDN contrast system when it is used. But, the results are more silver looking, so I did not miss the impossibly long tone I had developed several weeks ago.

I think that the extra Zones I brought into the process as few weeks ago were lost on most of the people who saw my silver prints at SPE. If you want endless tone – you have to go to Piezography. But, if you want an easier and higher standard of digital negative than you can make with color inks and PDN, you can bring Piezography inks into the PDN process. And if you want your own Piezography Digital Negative linearization tool, you can bring PDN into your workflow. A perfect marriage!

Now for some technical….

There are Curves and there are Curves. The Curves I make for use with QuadTone RIP are actually sets of individual inkjet curves we call a QTR Curve (or a .quad file). These are used to perfectly overlap shades of Piezography ink. The Curves exported by the Curves Calculator II of the Mark Nelson Precision Digital Negative system are .acv curves – which are Photoshop curves used in Photoshop to adjust an image so that it is linear when printed.

Below show the new QTR Curves I have generated in comparison to the QTR curves I generated in the earlier processes (onetwo, and three).

The first Curve presented below is the original Pictorico curve that I made which can still be used and is being used to make silver prints and alternative process. It is a one curve fits all approach that requires image compression to meet the density required in the negative.

This curve can produce a film that has a very long smooth range of density that gets progressively darker until it is fully opaque 3.0.

The second curve is linearized directly to the alt process and while this creates the best possible result – it will simply be too much work to release this as a system; requiring extensive amounts of development time to produce a curve for many of today’s different silver papers and alternative processes. It is also reversed to make a negative from a positive and it automatically masks unprinted areas of the film with dense enough ink so that white borders can be produced during contact printing. And if you imagine that it might be cool to print the film base+ fog – it does… If I dedicated myself to making digital negatives for every one of my favorite photographic processes – this would be heaven. Total overkill and a fantastic challenge in curve making.

Designed specifically for my favorite Ilford Fiber Paper.

The next five slides are five of the new QTR curves I made last week for use with Mark Nelson’s PDN system. But, they work without the PDN system. So the exercise really was to see what does the PDN system bring to negative making. So, for my own work I prefer not to use adaptive contrast of PDN – although I can see how creative it can be. I prefer to do these same changes with a simple Photoshop curve myself. PDN applies an adaptive contrast linearization, and the Piezography Digital Negative is already linear. I believe the appeal of PDN must be there to mix these two systems. We do not use PDN at Cone Editions Press, or at InkjetMall where we make digital negatives for photographers.

These five slides allow you to see how varying film densities are produced by very specific curves in QTR. Incidentally, all black ink is eliminated in the new curves and Shade 2 is used instead. Would take a microscope at this point to find stray dots in the hightlights of a Piezography Digital Negative!

You can look at the ink recipes on the left side of each slide and get an idea of the changes I have made over the past month. And a density scale at the bottom of each slide shows the progression of tone so that you can look vertically up from any density point to see what combination of inks are used to make that.

THe curves are all based upon a dMin of film base+ fog and a dMax that is triggered by the actual curve and available in five film dMax which should be matched to necessary density range required by the alternative process or silver paper: 1.40, 1.50, 1.60, 1.70, or 1.80.

Incidentally, for the PDN part of this process, only a portion of the PDN system is actually needed: the Tonal palette and the Curves Generator. The laborious front part of PDN which involves printing test charts and ink density charts, etc is not required. All of that work is done for you with the Piezography Digital Negative curves.

Without going into detail about all the components in the Precision Digital Negative system that are unnecessary to use with Piezography Digital Negatives – I will mention that these PDN steps are skipped in my process when used with PDN:

  • Perform a Project Baseline Printing Time Trials
  • Perform a Project Standard Printing Time Trials
  • Perform a Project Color Density Range Palette

The only part of the Nelson system that is needed is to print the “21StepTabletInkjet” image from QTR using my one of my new QTR curves, contact print this in the darkroom, and measure the results with a densitometer and perform the

  • Project Tonal Palette


This will create a set of density measurements that will allow you to “linearize” your output with a Photoshop curve that is exported from the Nelson system. The Photoshop curves are produced by the Curve Generator in Nelson’s CurveCalculator II. The entire time spent with Nelson’s PDN is a tiny fraction of what would be spent if you were using color inks.

But, it is a very powerful system that will allow you to export a Photoshop curve that will “linearize” your image or adjust it in a wide array of interesting contrast effects. This portion of the system is where all the creativity happens. I highly recommend PDN for use with Piezography Digital Negative.

Do you absolutely need the PDN system to use Piezography Digital Negatives? No. The Piezography film curves in QTR produce open shadows. The prints might be a little dark without linearization and you could actually just apply a simple mid level boost in Photoshop and be satisfied. But, the PDN system adds a way to boost contrast while at the same time making sure things are linear. It’s a no-brainer solution and it’s only $50. I can’t imagine anyone would not want to add this onto Piezography Digital Negatives.

But, where the PDN system really shines is its ability to darken shadows and brighten the highlights. It will help make the system look decidedly silver without closing up everything. The PDN system when used with Piezography inks can be considered to be more of a contrast control system. That is how I would characterize it when used with Piezography digital negatives.

The PDN system can produce a numbing array of Photoshop Curves if you wish to play with the double hybrid features. To give you an idea of some of the more basic curves, I have plotted their results by measuring the 21 step tablet from an Ilford RC print that I made from a Piezography film in which the 21 step file was adjusted with a PDN curve.

PDN Curves

The SL is straight line. I liked this curve the least because it made a very dark print. Mark’s linearization process appears to be Gamma 1.0 based – so it’s actually very straight line. But, if you begin playing with what Mark calls the Hybrid Value, you can then build contrast curves. Any value between 0 (Straight Line) and 1.0 (HD) can be used.

The HD is the most contrasty of the curves and you can see this readily in the Orange graph line that was plotted from actual density measurements from the silver print. But, if you like the properties of one curve in the shadows for example, and like the properties of another curve in the highlights… you can combine these into a new curve Mark calls a Double Hybrid Curve. And this is where the power and elegance of Mark’s system comes to enhance Piezography digital negatives.

All of these curves were made using the 21 step strip, one time through in a process that took less than one hour in the darkroom. PDN offers a process for fine tuning if desired. And PDN has a target with a much higher resolution of measuring points (101 gray steps) available in the first version of PDN. The quick and dirty method however is quite satisfying. How much time you wish to spend perfecting the curves is totally up to you.

QTR Curves = 32k34-16-lin_d1_4 (through 1.8).quad
32k34-16-lin_d1_4 (through 1.8).quad

What Piezography Digital Negative and Precision Digital Negative do for each other is to form a synergistic relationship in which the user will be able to generate the best possible results.

So, what’s next? Really my digital negative work is now nearly done. I plan to generate a series of density curves for all of our supported printers of which we still have a printer: R1400, R800/R1800, R1900, R2400, R2880, 3800, 3880, 4000, 4800, 4880, 7600, 7800, 7880, 7900, 9600, 9800, 9880, 9900. I will also try and create smooth dotless curves using shades 2, 3, 4, 5, 6, so that current Pieography users can make their own negatives without having to use the new half-shades. Then I need to write a manual so that it’s easy to understand for use with or without the PDN system – and of course an easy manner of converting EyeOne Lab data to density measurements for input into PDN.

Then I move on to creating a Piezography Digital Positive for digital photopolymer gravure. I plan to begin that work in May and will document it here. My 36″ x 72″ etching press awaits… I spent a decade making aquatint photogravures before giving it up in 1991. I can’t wait to get inky again. 🙂 
Piezography Digital Negative meets Mark Nelson's Precision Digital Negative (PDN optional not required)
Jon Cone
28 March, 2011
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