1. A captured-image recognition apparatus comprising: a memory that stores instructions; and a processor that, when executing the instructions stored in the memory, performs a process comprising: estimating a visual field ratio of a target in a captured image, using at least two kinds of detecting methods that detect different kinds of targets, the visual field ratio being a ratio of a target size in the captured image to a field-angle size of the captured image; selecting, based on the estimated visual field ratio, at least one candidate image recognition application from a plurality of image recognition applications that recognize different kinds of targets; performing image recognition by executing an image recognition application selected from among the at least one candidate image recognition application; and optimizing the visual filed ratio based upon the selected image recognition application.