the present invention provides a method of and system for determining whether a local area of a compressed video stream represented by a plurality of dct encoded blocks subject to decoding and filtering / scaling is a stationary area or an interlaced moving area . further , given such information , the invention relates to dynamically switching between frame - or field - based operations in a smart way , thus optimizing the output picture quality . also , a dct - domain - filtering scheme for field - based filtering / scaling of frame - dct data is provided herein .