Provided are an apparatus, a method, and a program for processing an image which reduces crosstalk and achieves high image quality. The method includes obtaining a differential signal by subtracting one input image signal of an object to be processed from another input image signal; applying a predetermined correction coefficient to the differential signal; determining, for each pixel, whether the differential signal is a negative value; selectively outputting, for each pixel, the differential signal, to which the predetermined correction coefficient is applied, as a correction signal based on a result of the determining; and correcting, for each pixel, the one input image signal based on the one input image signal and the correction signal that is selectively output if the differential signal is the negative value.