1. A method for eliminating a block artifact phenomenon of a block based decoded image frame, the method comprising: extracting pixel information comprising a magnitude of edge response, an edge direction, and an edge position by applying an edge detector to an arbitrary pixel in the image frame; distinguishing the pixel between a non-edge pixel, an object edge pixel, and a block edge pixel by using the extracted pixel information, wherein distinguishing the pixel further comprises comparing the magnitude of edge response of the pixel with a predetermined threshold value, and when the predetermined threshold value is greater, distinguishing the pixel as a non-edge pixel wherein distinguishing the pixel further comprises: when the magnitude of edge response is larger, determining whether the edge direction of the pixel is 0° or 90°, and when the edge direction is determined not to be 0° or 90°, distinguishing the pixel as an object edge pixel; and when the edge direction is determined to be 0° or 90°, determining whether the pixel is located around a block boundary region by using the edge position information, and when the pixel is determined to be located around the block boundary region, distinguishing the pixel as a block edge pixel; and performing filtering according to the distinguishing result.