Deskew is a command line tool for deskewing scanned text documents. It uses Hough transform to detect "text lines" in the image. As an output, you get an image rotated so that the lines are horizontal.
I found the problem. The source tiff was 300 dpi in pixels/inch, the program output 118.11 pixels/cm which is 300 pixels/inch. To avoid confusion you should preserve the source measurement system (metric or standard) as well.
Original report by Marek Mauder (Bitbucket: galfar, GitHub: galfar).
From blog comments: