Hello,
I did some experiments and it looks like this method can't detect skews below one degree. Could you confirm this?

This is the output for the testing image (I manually introduced a skew of -0.5°):

Angle bins: [[0.50279329608938206, 0.50279329608938206], [90.0, 90.0, 90.0, 90.0, 90.0, 90.0, 90.0, 90.0, 90.0, 90.0, 88.994413407821213, 90.0, 90.0, 88.994413407821213], [], [-88.994413407821227, -88.994413407821227, -88.994413407821227, -88.994413407821227]]
Estimated Angle: 90.0
Average Deviation from pi/4: 44.6480446927

This is the ouput with a non skewed image:
Image File: c:\users\dturato\appdata\local\temp\1\tmp7u2snw.png
Angle bins: [[], [90.0, 90.0, 90.0, 90.0, 90.0], [], []]
Estimated Angle: 90.0
Average Deviation from pi/4: 45.0

So it looks like is detecting something, but it is someway lost in the final computation of the angle single value.