1. An image correction method for a cathode ray tube (CRT) television system, the method comprising the steps of: (a) responding to an operation event to obtain a plurality of gain values; (b) determining n offsets, which respectively correspond to n segments between any two adjacent nodes of (n+1) nodes, according to the gain values and a plurality of correction functions corresponding to the gain values, each of the n segments having an original segment length, wherein n is a natural number; (c) correcting the original segment lengths of the n segments to generate n adjusted segment lengths according to the n offsets; (d) determining corrected positions of the (n+1) nodes according to the n adjusted segment lengths and a data enable signal; and (e) determining pixel positions and corresponding image data between the two adjacent nodes of the (n+1) nodes according to ratios of the n adjusted segment lengths to the corresponding n original segment lengths.