A
projection method is provided, and includes the following steps: projecting a first image according to an original image; capturing the first image; correcting the first
image based on the original image to generate a corrected image; comparing the corrected image with the original image to obtain a difference area; generating a second image according to the original image and the difference area, wherein the second image has a dark region associated with the difference area; and projecting according to the second image.