Regardless of the workflow you use to make digital negatives, consistency is the key to achieving repeatable results. It’s worth questioning whether or not the original step wedge was made in gray gamma 1.8 or gray gamma 2.2.
A three step method for making digital negatives by Ron Reeder and Christina Z. Anderson, an excerpt from Gum Printing and Other Amazing Contact Printing Processes.
The chapter called “Desktop negatives” of Sarah Van Keuren’s book “A Non-Silver Manual: Cyanotype, Vandyke Brown, Palladium & Gum Bichromate with instructions for making light-resists including pinhole photography”, written by Sandra C. Davis.
Alex Tymków outlines a method of combining pyro, digital negs and alt. proc.
Starting out with making digital negatives you may come across some terms you’ve never seen before, like "gamut", "ppi" and "random dots". This glossary may make a little more sense of it all.
There are several different ways of making a digital negative, but all seem to involve a Photoshop curve at some point. In this article geologist Clay Harmon applies his skills to photography and has developed his own curve for a Pyro-like digital negative – to be used with an Epson 2200, but, it can also be tweaked for other printers. All free to download here.
An easy way to make interesting negatives with the help of a computer. If you think Photoshop is too expensive – The Gimp is a cheaper program – it’s actually free.
Mike Ware’s book: Making Digital Negatives with an Ink-Jet Printer