1. A computer-readable recording medium recording a program for image processing causing a computer to function as: a captured image acquiring unit that acquires a captured image captured by an imaging device; a display controlling unit that displays an image including the captured image on a display device; and a feature detecting unit that detects, from the captured image, a feature in a real space captured in the captured image, using an image for detection of the feature, wherein when the captured image acquired by the captured image acquiring unit is a reversed image, the feature detecting unit performs a reverse comparison process to detect the feature, the reverse comparison process involving: comparing the captured image with a reversed image of the image for detection; or comparing an image obtained by further reversing the captured image, with the image for detection.