Various block truncation coding （BTC） algorithms proposed till now are in factthe two level quantizers. They quantize each image block into two levels

which result in obviousblocking effect especially in edges in the decoded images. In order to reduce the blocking distortion

we adopt a smooth filter for BTC and obtain modified block truncation coding（MBTC） algorithms. The experimental results show that MBTC can achieve the better image quality than otherBTC schemes

and decrease the blocking disortion.