The method includes following steps: a) provides image signal temporary storage area containing at least two memories; each capacity of memory is less than 1/2 total pixels of image frame, and more than or equal to the total pixels of a group of image signals; b) the multi groups of image signal are inputted in turn to the two memories and are made image processing; when one of two memories only stores one group of image signals, the other groups of image signals in the image frame, which are not inputted into the temporary storage area, are inputted by turns, and covers the image signals in the temporary storage area, which has completed image process. |