Rendering algorithms: Inverting negative to positive

Inverting negative to positive

If the original image is a negative, then we first need to simulate process of contact-copying negative to a transparency. Basic invertion to negative may be done by setting gray_range in a way minimal value is greater than maximal.

Future plans

Realistic simulation of what happens when negative is copied to a transparency in laboratory involves simulating sensitivity curve of the black and white emulsion used. At the moment this step is not implemented in a satisfactory way and we rely on other tools (such as vuescan) to do this job for us. We yet need to understand how typical sensitivity curves were and what kind of user-interface we want to implement here. Ideally we should do this based on scans of existing negative-transparency pairs.