Finding T1, T2 andT14

T1

When the test strip is dry, find the first tone that is just white by comparing the tone against the adjacent white paper.  The RGB value of that tone is the “just white” tone and labelled T1.

In the above illustration of a Van Dyke Brown test print T1 is RGB 24.

T2

Compare the test print “highlight” tones against the white adjacent strip to find the print RGB value with the same relative contrast to white as the T2 tone on the monitor. The RGB value of that tone is called the “Threshold” and labelled T2.  In the above illustration T2 is RGB 37 .

Do not overthink this, if in doubt choose a slightly lighter tone

T14

T14 is the first visible tone from black and should have the equivalent contrast to black as T14 has to black on the monitor. Again, do not overthink this, if in doubt choose a slightly darker tone. In the above illustration T14 is RGB 130.

The stepwedge should have a mid grey background and the monitor set to a gamma of 1.8 and RGB 16 should be just separated from RGB 0. It is suggested to keep the monitor contrast and brightness relatively low to be closer to the characteristics of reflective prints.

Enter T1, T2 and T14 into the spreadsheet to create and plot the inverted file’s true negative curve.

Adjustment for Different Photo Editing Programs

For some reason different programs use different scales in the curve dialogue. Photoshop goes from zero to 255 , GIMP goes from zero to 100 and Affinity zero to 1. TruNeg deals with this by providing a cell in the second row of the Control Panel where the maximum curve dialogue value must be entered to adjust the TruNeg scale to match the editing software.

Record Keeping

Working with digital negatives and alternative photographic processes involves a lot of accurate record keeping. To make this easier TruNeg records the material and curve details which can be copied and pasted to save to the spreadsheet, curve etc. It may need to be pasted into a text file like Sticky Notes or similar simple text file for a temporary record and recopied before it can be pasted into the negative border, ACV title etc...

If the contents of the “Save As “ cell are accidently deleted the contents can be restored by entering =M4 into the cell for Excel, or =M3 for the ODS file. A reminder is located beside the “Save As” cell.