An object of the present invention is to provide an image processing apparatus, an image processing method, and a program capable of interpolating a gain of a pixel value of a phase difference detection pixel using a gain value even in the case of generating a display image requiring a real-time property. An image processing apparatus (60) sequentially obtains each frame image in time series order of a motion picture and calculates a gain value to be used in gain interpolation of a pixel value of a phase difference detection pixel of a current frame image based on a past frame image obtained in the time series order. The image processing apparatus (60) interpolates the pixel value of the phase difference detection pixel of the current frame image using the gain value.