1. A digital image classifying method, comprising the steps of: performing a discrete cosine transform (DCT) on a candidate area of a digital image to generate a set of DCT coefficients; generating a set of texture parameters according to the set of DCT coefficients; and generating a classified result of the digital image according to the set of texture parameters; wherein the set of texture parameters comprises at least one of the following parameters: a smooth texture energy (EDC), a vertical/horizontal texture energy ratio (EV/EH), and an oblique texture energy (ES); wherein the classified result is a category of people or a category of scenery wherein the candidate area is generated by the steps of: (a1) dividing the digital image into a target area and a non-target area by using a color dividing method according to a target color; and (a2) selecting the candidate area from the target area by using a morphometric analysis and an 8-adjacent connection analysis.