1. A method for recognizing an object from two original images, which are captured at the same time respectively by two cameras that are spaced apart from each other and that have an overlapping field of view containing the object, the method to be implemented by an electronic device and comprising the steps of: (A) configuring the electronic device to access the two original images; (B) configuring the electronic device to reduce resolutions of the two original images so as to generate two resolution-reduced images, respectively; (C) configuring the electronic device to calculate a plurality of shift amounts, each of which is between two corresponding pixels in pixel blocks that have similar content and that are respectively in the two resolution-reduced images, and to generate a low-level depth image based on the shift amounts, a larger one of the shift amounts representing a shallower depth on the low-level depth image; (D) configuring the electronic device to determine an object area of the low-level depth image containing the object therein; and (E) configuring the electronic device to obtain a sub-image, from one of the original images, corresponding to the object area of the low-level depth image determined in step (D), thereby recognizing the object based on the sub-image.