We previously developed an image reconstruction display for reconstructing images compressed by our hybrid
compression algorithm. The hybrid algorithm, which improves image quality, applies Discrete Cosine Transform
coding (DCT) and Block Truncation Coding (BTC) adaptively to an image, according to its local properties. This
reconstruction display receives the compressed data from the host computer through a BMC channel and quickly
reconstructs good quality images using a pipeline-based microprocessor.
This paper describes a prototype of a system for compression and reconstruction of medical images. It also
describes the architecture of the image compression processor, one of the components of the system. This system
consists of the image compression processor, a host main-frame computer and reconstruction displays. Under this
system, distributed processing in the image compression processor and the image reconstruction displays reduces
the load on the host computer, and supplies an environment where the control routines for PACS and the hospital
information system (HIS) can co-operate. The compression processor consists of a maximum of four parallel
compression units with communication ports. In this architecture, the hybrid algorithm, which includes serial
operations, can be processed at high speed by communicating the internal data. In experiments, the compression
system proved effective: the compression processor compressed a 1k x 1k image in about 2 seconds using four
compression units. The three reconstruction displays showed the image at almost the same time. Display took less
than 7 seconds for the compressed image, compared with 28 seconds for the original image.