Provided are a method and an apparatus for filtering video data. The method includes determining whether a difference value of illumination change (DVIC) of a current image processing unit containing a current block is different from a DVIC of an image processing unit that is adjacent to the current image processing unit and based on the determining, adjusting a filtering strength of a deblocking filter and performing deblocking filtering on a boundary of the current block using the filter with the adjusted filtering strength.