cropneg is a darktable plugin that automatically crops negative scans by exposed area bounds. Main application is written in go using GoCV library.
The project was inspired by this proof of concept.
Application tries to find exposure bounds of provided image by gradually thresholding it.
Cropping works best if your scan has good contrast between exposed area and film base.
Download the archive, place cropneg binary in your $HOME/bin folder.
Place the crop_negative.lua in the $HOME/.config/darktable/lua and then add require "crop_negative" to the luarc file in $HOME/.config/darktable.
For more information about the lua scripts for darktable see this and this.
In darktable select enable auto crop checkbox located under the export tab. Selected images will be cropped
automatically in the export process. If application is unable to properly detect exposed bounds of scanned image, then it will
be exported without any cropping.
Currently this application can run on linux.