1. A method for controlling image display, comprising the following steps: determining whether a still image appears; obtaining, when a still image appears, an actual gray-scale of each pixel of said still image, and generating a plurality of output gray-scales corresponding to the actual gray-scale; and substituting the actual gray-scale with said output gray-scales alternately, and forming dynamic image output, wherein the plurality of output gray-scales comprise a first output gray-scale and a second output gray-scale that are different from each other; and wherein the first output gray-scale represents a high gray-scale relative to the actual gray-scale, and the second output gray-scale represents a low gray-scale relative to the actual gray-scale, wherein the step of forming dynamic image output further comprises: generating a first image and a second image based on the first output gray-scale and the second output gray-scale corresponding to the actual gray-scale of each pixel, and substituting an actual gray-scale image with said first image and said second image in a predetermined manner alternately so as to form dynamic image output, wherein when said first image and said second image are output, the first output gray-scale or the second output gray-scale corresponding to the actual gray-scale of each pixel is output, and wherein when said first image and said second image are output, an output order of the output gray-scales of each pixel is different from an output order of the output gray-scales of adjacent pixels.