1. An image capturing device capable of simplifying characteristic value sets of captured images, comprising: a characteristic conversion module, for converting a captured image into a characteristic image which includes a group of first characteristic value sets; a data storage module, for storing a lookup table which comprises second characteristic value sets; a characteristic simplification module, for executing a simplification process according to the lookup table, and deleting the first characteristic value set not existing in the lookup table from the group of first characteristic value sets, and replacing each deleted first characteristic value set by the second characteristic value set matching with a predetermined condition and existing in the lookup table, so as to generate a simplified group of characteristic value sets; a template storage module, for storing a plurality of templates; and a recognition module, for comparing the simplified group of characteristic value sets with the plurality of templates to recognize a specific object in the captured image.