1. An image processing device comprising: an image acquiring section configured to acquire a plurality of captured images captured by one or more capturing persons with two or more capturing devices of different types; a capturing information acquiring section configured to acquire, as capturing information, information on a capturing person, a type of capturing device and a capturing time for each of the captured images; an image extractor configured to extract, from the captured images, captured images regarded as being captured in a same time range based on the information on a capturing time, as extracted images; a target image determiner configured to sort out the extracted images on a capturing person basis and a capturing device type basis based on the information on a capturing person and a type of capturing device, select one of extracted images which were captured by a capturing person who captured largest number of extracted images and were captured with a capturing device of a type used to capture largest number of extracted images based on a result of the sorting out and determine the one of the extracted images selected, as a target image for color conversion; an image analyzer configured to carry out image analysis on the extracted images; an object image determiner configured to select, from among the extracted images other than the target image, one or more similar images that are extracted images each showing a subject similar to a subject present in the target image based on a result of the image analysis and determine the one or more similar images selected, as one or more object images to be subjected to the color conversion; a color table generator configured to generate a color table used in the color conversion for matching colors of the one or more object images to colors of the target image based on the result of the image analysis; and a color conversion processor configured to carry out the color conversion by applying the color table to the one or more object images.