Auto determine angle range for skew detection

[galfar]

Right now skew detection is by default done in [-10°, 10°] angle range. This limitation is there to keep the time taken by the detection reasonable for the most likely inputs (scanned pages slightly misaligned). User can change this range with -a parameter.

Also to keep the time down the range is searched in sampling steps of 0.1° so skews lower than this cannot be detected.

Proposal: do a two pass detection. First in a much bigger range that current default (+/-45°?) with bigger sampling step (2-5°?). Then do a finer second pass in a vicinity of skew angle detected by the first rough pass.

No idea how well this could work :slight_smile: