By use of the characteristics that an analog-to-digital converter sends out data sequentially when it converts data of a two-dimensional analog image into pixel data, a fingerprint image detecting device and method generate digital output data having a plurality of rows of data, generate a plurality of one-dimensional datum segments linearly from the digital output data, and determine whether the two-dimensional analog image is a real fingerprint image according to the plurality of one-dimensional datum segments. Thus, the detection of a fingerprint image is implemented by means of one-dimensional calculation instead of two-dimensional calculation, thereby effectively reducing computational load and computational time.
