12 Wavelet - Based Progressive Transmission and Security Filtering for Medical Image Distribution

With the rapid expansion of computer networks, communication and storage of medical information has entered a new era. Teleclinical practice and computer digital storage are two important medical information technologies that have made the issue of data compression of crucial importance. E ciently compressing data is the key to making teleclinical practice feasible, since the bandwidth provided by computer media is too limited for the huge amount of medical data that must be transmitted. Because of the high compressibility of the medical images, data compression is also desirable for digital storage despite the availability of inexpensive hardware for mass storage. This chapter addresses the family of progressive image compression algorithms. The progressive property is preferred because it allows users to gradually recover images from low to high quality images and to stop at any desired bit rate, including lossless recovery. A progressive transmission algorithm with automatic security ltering features for on-line medical image distribution using Daubechies' wavelets has been developed and is discussed in this chapter. The system is practical for real-world applications, processing and coding each 12-bit image of size 512 512 within 2 seconds on a Pentium Pro. Besides its exceptional speed, the security lter has demonstrated a remarkable accuracy in detecting sensitive textual information within current or digitized previous medical images.