A processing apparatus (1) according to the present invention is an image processing apparatus configured to process a first image signal having a picture portion in which a subject is shown and having a blank portion surrounding the picture portion. The processing apparatus (1) includes a blank detection unit (13a) configured to detect a blank portion of the first image signal, and an enlargement-reduction unit (13c) configured to set an initial region-of-interest corresponding to the picture portion based on the blank portion detected by the blank detection unit (13a) and to generate a region-of-interest image signal by enlarging or reducing the set initial region-of-interest.
