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

Solving the Problem of the Digital 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,

Researching the problem showed that the issue is that the editing software uses linear scales and arithmetic to invert and print the negative, which conflicts with the logarithmic nature of photographic materials.

Understanding this problem led to the creation of the TruNeg application, which uses logarithms to perform the calculations needed to generate the “photographic” negative from the positive. The negatives capture the full range of tones from the darkest shadows to the brightest highlights and can be relied upon to perform correctly with any image.

The application features:

  • Authentic photographic negatives created in less than a minute from just two inputs obtained from a single test strip, without the need for densitometers, scanners, linearisation procedures, etc

  • Logarithmic interactive plots that allow the user to accurately adjust the print tones to meet their idea of the ideal print.

  • Profiles for Argyrotype,  Carbon (A. Dichromate)/Gum Bichromate, Classic Cyanotype,  Salt, and Van Dyke Brown.  The profiles correct the low contrast inherent in the highlights and shadows of photographic materials and are available for free on the website.

In general, prints from TruNeg negatives cannot be distinguished from those made with silver gelatin negatives, except that, with the ability to control the highlights and shadows, prints can be made with subtle highlights and rich shadows from notoriously difficult processes such as Classic Cyanotype.

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.

2. Convert:

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.

3. Tweak:

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.

Plot of a Classic Cyanotype curve

TruNeg Demonmstartion

How to make a print using the Salt process.