1. A correcting method for a display apparatus, comprising: a) measuring respective color performances of the display apparatus for N original grayscale combinations, to generate N measurement results, where N is a positive integer greater than 1; b) utilizing a set of color blending equations for M original grayscale combinations according to the N measurement results to generate M blended results, where M is a positive integer; c) establishing a color performance database comprising (N+M) color performances according to the N measurement results and the M blended results; d) identifying P color performances respectively most approximate to a P predetermined target color performances from the color performance database, wherein P is a positive integer; wherein, the P target color performances correspond to P target grayscale combinations, and the identified P color performances correspond to P original grayscale combinations in the (N+M) original grayscale combinations; and e) establishing a look-up table (LUT) according to the P target grayscale and the P corresponding grayscale combinations.