This image-processing device has: a storage unit for storing previously acquired three-dimensional image information pertaining to a test subject a hollow organ extraction unit for extracting a prescribed hollow organ present within a three-dimensional image an information acquisition unit for acquiring information pertaining to an observed location observed within a prescribed hollow organ by an objective optical system, and to the line-of-sight direction a boundary location generation unit for generating boundary location information indicating a boundary location between an in-angular field area and an out-of-angular field area in a three-dimensional image of the prescribed hollow organ an out-of-angular field area extraction unit for extracting an out-of-angular field area that has not entered the angular field in the three-dimensional image of the prescribed hollow organ, doing so on the basis of boundary location information that changes in association with temporal changes in the observed location and the line-of-sight direction and an image generation unit that generates an identifying image in which identifying information identifying an out-of-angular field area is appended to a three-dimensional image of the prescribed hollow organ.Linvention concerne un dispositif de traitement dimage, qui comprend : une unité de stockage pour stocker des informations dimage tridimensionnelle précédemment acquises, concernant un sujet dessai une unité dextraction dorganes creux, pour extraire un organe creux prescrit présent à lintérieur dune image tridimensionnelle une unité dacquisition dinformations pour acquérir des informations concernant une localisation observée à lintérieur dun organe creux prescrit par un système optique dobjectifs, et la direction de la ligne de vision une unité de génération dune localisation de frontière, pour générer des informations de localisation de frontière indiquant une localisation de frontière entre une zone dans le champ angulair
