1. An information processing device comprising: an image processing circuit configured to: control detection of motion of a subject included in an image generated by an imaging device, wherein the imaging device includes a plurality of phase difference detecting pixels which generate a signal to perform focus determination by phase difference detection, and a plurality of image generating pixels which generate a signal to generate an image; and determine a thinning-out processing when reading out a signal from the imaging device, according to the detected motion of the subject in an event of imaging a still image, wherein the thinning-out processing is determined to be a moving image thinning-out mode, in an event of imaging a moving image, to generate an image using a signal read out from one or more lines not including the plurality of phase difference detecting pixels regardless of the detected motion of the subject.