To perform an image processing for high resolution more suitably on even an image signal having images with different resolutions mixed therein. An image signal processing method of the present invention includes the steps of: performing a spatial low pass filter processing on a first image signal that is an input image; generating a second image signal by performing an image processing for high resolution on an image after the low pass filter processing; comparing corresponding regions in the first image signal and the second image signal; and selecting either of the first image signal and the second image signal with respect to the region based on this comparison result.