Solving the Problem of the Digital Negative

Don’t waste your time trying to fix incorrectly inverted negatives

The True Digital Negative

A whole mythology has developed around how to fix the inverted “negative” produced by the editing software.  This mythology has become so entrenched that it continues unchallenged without questioning or examining the source of the problem.

However, a little mathematics shows that the negative of any positive image can be calculated from the inverse proportion between the positive and negative logarithms.

This fundamentally changes the way digital negatives can be made, it eliminates the need for densitometers, scanners, linearization procedures, etc., and, with a press of a button, enables the calculation of a true photographic negative that mirrors every shadow, midtone and highlight of the positive image.

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

The Alternative Process and Profiles

Each alternative process has its own characteristic DLogE curve, and if the curve of the alternative material is known, the difference between the plot of the digital negative and the material’s curve can be calculated, recorded, and saved as a correction profile.

TruNeg has been done for Argyrotype, Classic Cyanotype, Carbon/Gum Bichromate(A. Dichromate), Salt and Van Dyke Brown, and their profiles can be downloaded from the website. A Generic profile is included to assist users for processes not yet listed.

A description and the curve of each profile, along with some comments about the process, can be found under the Profiles menu.

The Curves Window

The chart, which plots the positive and negative logarithms, is effectively a DLogE graph. The profiles counteract the process’s low contrast in the shadows and highlights so that the print matches the monitor.

Each gridline corresponds to a tone in the stepwedge included in the Test Strip Template, making it easy to visualize and predict changing the tones in the print when amending the curve.

  1. Enter the two RGB values that produce ”just white’ and ‘just black” from a print of the Calibration Negative as shown above, load a profile and Save.

  2. In the Convert Menu, open a test strip of the image, select the preset and press OK to convert it into a negative.

  3. Print the negative, print and check the test strip.









  4. As necessary, correct any unsatisfactory tones in the Curve window and reprint the test strip with the new preset.

Using the Application

The Curve window finishes off the print, whether touching up the highlights or bringing out the shadows, there is nothing to stop the user from achieving the exact print they are after.

Note that the TruNeg app is applicable to any process and printer.
Video Showing How to Make a Salt Print