Progressive image transmission (PIT) transmits the most significant portion of a picture, followed by less important parts. The mechanism can be used in web-based applications, while users are browsing images. Most PIT methods use the same pixel interpolation scheme for the entire picture, without considering the differences in different portions. We test several strategic decomposition mechanisms. Our contribution results in an adaptive image transmission mechanism, which takes the differences of pictures and picture portions into consideration. We tested 1500 pictures in different categories and parameters. The overall bit rates can be reduced significantly, with good PSNR values. An error recovery procedure is also implemented to guarantee the transmitted pictures that can be fully recovered. Interested readers can find the prototype tool and our evaluations at http://www.mine.tku.edu.tw/demos/ProgTransmission.