Abstract: In image compression techniques based on block coding,blocking artifacts occur near the block boundaries of the decoded images at low bit rates.In this paper,an efficient deblocking algorithm in DCT(discrete cosine transform) domain is proposed.The shifted block is obtained directly from its adjacent blocks via the decomposition and combination of DCT coefficient blocks.After block activity classification,for the shifted block between lowactivity adjacent blocks,the improved linear function is used to replace the step function to eliminate blocking artifacts,and then the shifted block is used to update its adjacent blocks.Finally,the post-filtering and quantization constraint techniques are adopted to post-process the updated and high-activity blocks.Experimental results show that the proposed approach can effectively reduce blocking artifacts and preserve the image textures and edges.