Solving the Problem of the Digital Negative

Copy of Carbon Print (Oxide Black) made with m a TruNeg Negative

The idea of creating prints on antique and alternative photographic materials from negatives inverted in the editing programs and printed on inkjet printers has generated a great deal of interest and activity worldwide.

However, there is a major problem: the negatives produced by the editing programs do not work. The reason for this is that the editing programs use arithmetic to invert negatives.

TruNeg uses the correct maths to produce authentic photographic negatives that produce prints indistinguishable from those made with silver gelatin negatives.

Photographic materials, to varying degrees, have low contrast in the shadows and highlights, and a print of a correctly inverted negative will, to some extent, have blown-out highlights and overly dark shadows.  

To counteract this, TruNeg has tested and developed several profiles that can be downloaded free of charge from the website. Currently, these include Argyrotype, Carbon(A, Dichromate)/Gum Bichromate, Classic Cyanotype, Salt and Van Dyke Brown.

Three Steps to Great Prints

  1. Calibrate:

Calibration establishes the exposure and contrast parameters of the printer/process combination. These are entered into the program along with a copy of the process profile and saved as a preset.

Plot of a Classic Cyanotype curve

Import the image, load the profile and press OK. The program goes through the image pixel by pixel and calculates the negative value. A 29x19.5 cm 360 dpi image takes about 30 seconds.

When conversion is complete, the negative is automatically exported back to the image’s folder, ready for printing by the editing program.

2. Convert:

After assessing a test print, the user can tweak the plot to amend the negative and lighten or darken unsatisfactory tones.

The grid guides the user in deciding how much to modify the curve, whether the T15 highlight should be one or two steps darker, or the T6 shadow half a step lighter. This gives the user full control over the print, whether to touch up the highlights or drag down the midtones and shadows to make a more dramatic print.

While some experience is required, the user should be able to get that “perfect” print from two or three test trips.

3. Tweak:

Making a Salt Print

How to calibrate, convert and tweak a negative to produce a print using the Salt process.