When making digital negatives we have ended up using two different methods. Quite straightforward and simple way with inkjet printers is to let the printer render the grayscale image using all inks. These transparencies are easy to read and evaluate, and corrections to the tone scale can be done with effortless and straightforward thinking. This method usually seems to suit art students well – they want quick results and donÂ’t care to make the matter too scientific. 😉

The easiest way to make a digital negative is to print the image file, converted to grayscale and inverted to negative, onto suitable transparency material. It is also the fastest way, but the final result will not necessarily be very good, because the tone range of the original image will distort somewhat when the neg is contact printed, depending on the contact printing process used, and you will need a method for correcting the tone scale. Usually you can make corrections using a correction curve attached to the image file in Adobe Photoshop. Actually the correction curve should be built for every combination of printing process, printing paper, developer, and other variables occurring in the printing process.

We have started building correction curves in Photoshop in a simple way: by printing a digital negative with known gray tones on transparency, printing the negative with some standardized contact printing method (common silver print, cyanotype), measuring the print’s tone range distortion with a scanner or densitometer, building a correction curve to remove the distortion, and finally printing a new, corrected negative. We are printing with the Epson R1800 and Pro 3800, the transparency material is Agfa CopyJet film.

The purpose is to remove guesswork from exposing hand sensitized materials, so that with using proper correction curves we could easily produce “perfect prints” without too many tests.

This entire method is described very well in Digital Negatives, a book by Ron Reeder and Brad Hinkel. In fact we have used the step tablet image downloaded from the authorsÂ’ website in making our own correction curves.

tablet.jpg

We will post here some pictures of our curves and tests later.