1. A method for reducing a block effect in video file compression, comprising: inspecting an image in a row and column direction, comprising; selecting at least four adjacent pixels A, B, C, and D in the image; sequentially determining whether the block effect exists between the at least four adjacent pixels A, B, C, and D as follows: 
 | B−C|>|B−A| 
 | B−C|>|C−D| 
 | B−C |<Threshold_High 
 | B−C |>Threshold_Low where Threshold_High and Threshold_Low are predetermined upper and lower reference thresholds; calculating an intensity vector of the block effect responsive to the inspecting; obtaining distribution data for the block effect responsive to the intensity vector; and determining position information of the block effect responsive to the distribution data; and filtering the image responsive to the intensity vector and the position information.