Solving the Problem of the Digital Negative
Don’t waste your time trying to fix incorrectly inverted negatives
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.
The True Digital Negative
Research on how the photographic image is digitally recorded shows that the negative of any positive image can be calculated from the inverse proportion between the positive and negative logarithms.
This fundamentally changes how digital negatives can be made, eliminating the need for densitometers, scanners, linearization procedures, etc., and enabling the calculation of a true photographic negative, with a press of a button, 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, which has a significant effect on the print, and to make a successful print, these characteristics have to be taken into account. This can be done by calculating the difference between the plot of the digital negative and the curve of a successful print and saving the information as a profile.
TruNeg has done this 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 plots the positive and negative logarithms of the digital negative in blue and the profile in yellow. The profiles calculated by the program counteract the process’s low contrast in the shadows and highlights so that the print matches the monitor.
The profile plot is effectively an inverted DLogE curve where each gridline corresponds to a tone in the stepwedge included in the Test Strip Template shown below, making it easy to visualize and predict changing tones in the print when amending the curve.
Download and print the Calibration Negative and find the minimum exposure that produces a clean white and maximum density on the process.
Open the Calibration menu and enter the two RGB values that produce ”just white’ and ‘just black” from the calibration print, load the profile and save the preset.
gIn the Convert Menu, open a test strip of the image, select the preset and press OK to convert to negative.
Print the negative, print and check the test strip.
Correct any unsatisfactory tones in the Curve window and reprint the test strip with the new preset. See the video opposite.
When happy, print the print.
Using the Application
Summary
Starting with an authentic photographic negative, the TruNeg application provides a straightforward pathway using traditional test strips to create prints that can meet the needs of the most demanding user.
TruNeg applies the traditional darkroom practice of using test strips to build the print. While some practice with reading prints is required, a finished print can usually be achieved from the profiled negative with two or three test strips.
The application is quick and simple to use, getting the first test strip ready for printing within a few minutes of assessing the calibration print.
To Make a Print:
Note that the TruNeg app is applicable to any process and printer.
Video Shows How to Make a Salt Print