Frequently Asked Questions

Digital negatives have always been made by subtracting the positive pixel value from 255. But the relationship between exposure and RGB is logarithmic, and subtracting the positive value from 255, while making white black and black white, destroys the logarithmic relationship between exposure and the negative RGB.
The relationship between the original exposure and pixel value is logarithmic. Using the principle that the positive and negative logarithms are inversely proportional to each other, every negative pixel value can be calculated from the ratio between the logarithms. As this cannot be done in the editing programs, it requires a dedicated application to do the maths.
To the best of our knowledge, TruNeg is the only method or application that, first of all, defines what a true digital negative is, then uses mathematics to invert the negative in accordance with the definition.
A correctly inverted digital negative is a negative in which the pixel values decrease by a constant factor for each stop increase in exposure.