1. An image processing apparatus for applying a development process to a photographic image, comprising: an image processor, configured to generate a display image from the photographic image; an input section, configured to input an instruction indicating a reference region of the display image, and an adjustment instruction of a parameter for the development process of the photographic image; an extractor, configured to extract, as a similar region, an image region having a high correlation with the reference region; and a generator, configured to generate display images of the reference region and the similar region by applying the parameter for the development process to the photographic image, which corresponds to the reference region, and the photographic image which corresponds to the similar region.