using a processor to drive a camera to shoot frame by frame to obtain an image information, wherein the image information comprises a plurality of frames of images, the images are formed sequentially in time series, and each of the images comprises a plurality of pixels;

the processor obtaining a brightness value of each pixel;

the processor calculating an absolute value of brightness difference with a corresponding pixel in a previous frame;

the processor comparing the absolute value of the brightness difference against a preset threshold;

if the absolute value of the brightness difference is less than or equal to the threshold, judging the pixel as a static pixel, and superimposing the corresponding pixel of at least one previous frame image onto the pixel of the current frame image to form a resulted frame image; and

if the absolute value of the brightness difference is larger than the threshold, judging the pixel as a dynamic pixel, and replacing the pixel of the previous frame image with the pixel of the current frame image to form a resulted frame image; and

the processor outputting the resulted frame image.