A PDF of the full Instructions can be downloaded here:
There are two spreadsheet formats provided, one for Microsoft Excel and one in .ods which is an OpenDocument spreadsheet format. If you do not have a suitable program that operates Excel, OpenOffice is a free download available at https://www.openoffice.org/download/ No knowledge or experience is required, follow the OpenOffice download instructions, install the program and open the TruNeg file and you are set to go.
(Because the spreadsheet contains locked cells you may need to enable editing in the Excel file)
TruNeg works with any photographic editing software program that uses linear scales in its curve dialogue and has 8 to 16 independent control points.
The Spreadsheet has at least two main elements, the Control Panel and the Curves Chart
The Control Panel
The Curves Chart
The Chart vertical grid lines are the inputs from the inverted Truneg Step Wedge. The two vertical dashed lines divide the inputs into the highlight zone T1 to T5, the mid-tones T5 to T10 and the shadows T10 to T15. The horizontal lines are the true exponential negative outputs to the printer and will vary with the printer and photographic material. The decreasing width of the steps is caused by the exponential structure of the photographic image.
Depending on the printer inks and/or the process being used the curve can vary a great deal and it is important to understand that no one curve is better than another. The TruNeg curve is an exponential function, that is each tone is the same multiple of the tone before. If the starting tone, that is T2, is low then the curve will be flatter than for a higher starting point, but the relationship between the tones will be the same.
The first thing to do is to make sure the image file is set up properly.