1. An image processing apparatus, comprising: a light field data position determiner configured to determine a position of a portion of light field data among light field data corresponding to a scene, according to a desired focusing position; a refocusing image generator configured to generate a refocusing first image by use of the position determined portion of light field data; a high resolution image generator configured to generate a high-resolution image comprising a predetermined setting ratio, relative to the refocusing first image; a synthesis ratio determiner configured to determine a ratio for local synthesis between the high-resolution image and an enlarged image of the refocusing first image, by use of a similarity with respect to the position determined portion of light field data; and an image synthesizer configured to generate a synthesized image by synthesizing the high-resolution image and the enlarged image of the refocusing first image, according to the local synthesis ratio, wherein the synthesis ratio determiner is further configured to determine the ratio for local synthesis, such that the high-resolution image is synthesized with a higher synthesis ratio for a portion comprising a higher similarity with respect to the position-determined portion of light field data than a portion comprising a lower similarity with respect to the position-determined portion of the light field data, and wherein the desired focusing position corresponds to a highest sharpness refocusing image and the refocusing first image corresponds to the highest sharpness refocusing image.