In an image-frame processing method, the image frame is outputted from and image sensor by an image processor via the buffering of a memory buffer. The method includes the following steps of: defining at least two storage spaces in the memory buffer; dividing the image frame into a plurality of image portions, each of which has a size corresponding to the size of one of said at least two storage spaces; sequentially storing the image portions into the storage spaces in turn; and sequentially processing said image portions stored in the memory buffer. This method is applicable to processing the image frame with the use of a small-sized memory buffer.