Using the Straighten Columns Function
The Image->Straighten Columns and the Settings->OCR->Straighten Columns functions combines document layout analysis (to detect columns and graphics) and column straightening to perform the following operations:
Straighten each column of text (but doesn't touch single lines or short columns of 4 lines or less), can be single or multi-column pages
Remove clipped columns
Using this function can significantly increase OCR accuracy.
Note: Straighten Columns will not work very well on more extreme cases of cylindrical book curvature. As a consequence of this, it's recommended that you use your hands to flatten and reduce the more extreme cases of book curvature. Doing this in combination with using the the Straighten Columns function will be much more effective at book straightening.
Some examples of using the Straighten Columns function is given below in a sequence of input and output images: