According to one embodiment, an image processing apparatus comprises a screen, a camera, a distance sensor, and a processor. The screen has one surface where an object is put. The camera photographs an image from the other surface of the screen. The distance sensor measures a distance from the one surface of the screen and generates distance information indicating the distance. The processor extracts a region of the object from the photographed image, specifies the object from the image of the region of the object, acquires an outer dimension preset to the specified object, calculates a length, from the screen, of the object put on the one surface of the screen based on the distance information, and outputs an alert when the outer dimension does not match the length of the object.