Provided are an image processing device, an imaging device, a program, and an image processing method which can suppress a reduction in the visibility of a split image when distortion is corrected. A first display image which is used as a live view image and a second display image which is used to check a focus are generated on the basis of an image signal output from an imaging element including first and second pixel groups on which an object image that passes through first and second regions of an imaging lens and is pupil-divided is formed (S403, S415). The distortion of the first display image is corrected (S403, S411). The distortion of the second display image in a division direction is corrected and distortion in a direction orthogonal to the division direction is not corrected (S409, S417).