Image Converting Method and Related Image Converting Module

An image converting method includes calculating a plurality of segment averages of pixel values in a plurality segments of an input image; acquiring the maximum among the segment averages as a first threshold; calculating a plurality of local averages of pixel values in adjacent segments of input image; acquiring the maximum among local averages as a second threshold; counting the number of pixel values exceeding first threshold in the segments as a plurality of first pixel counts and counting the number of pixel values exceeding second threshold in the segments as a plurality of second pixel counts; generating a specular map and a confidence according to the first pixel counts and the second pixel counts; mapping the input image according to the specular map, to generate an intermediate image; and blending the input image and the intermediate image according to the confidence, to generate an output image.