A method for generating an image with uniform brightness, the method includes: providing a first sub-image having a first overlapping portion and a first non-overlapping portion; providing a second sub-image having a second overlapping portion and a second non-overlapping portion; and superimposing the first sub-image with the second sub-image through the first overlapping portion and the second overlapping portion. The brightness of the first overlapping portion of the first sub-image is complementary to the brightness of the second overlapping portion of the second sub-image.