1. An electronic apparatus, comprising: an input interface, being configured to receive a reference frame, wherein the reference frame corresponds to a plurality of luminance values; and a processor, being electrically connected to the input interface and configured to adjust at least a portion of the luminance values that are greater than a predetermined threshold according to an accumulation number and a predetermined discard number, calculate a weighted luminance value of the reference frame according to the luminance values, generate a comparison result by comparing the weighted luminance value and a luminance target, and decide the luminance values according to the comparison result.