A network-reactive model for distributed telemicroscopy

We have developed a network-reactive robotic telemicroscopy system that uses high-speed image processing and quality of service (QoS) feedback to maximize performance. In tests, four magnifications (4 x, 10 x, 40 x, 60 x ) of a section stained with haematoxylin and eosin were used. Up to 25 clients, distributed across two Internet domains, accessed the server. When given control of the microscope, any of the clients could direct the microscope to change focus and objectives within 3 s and move the stage to any x-y position within 1 s. Transmission rates of 50-200 kbit/s were achieved for video (320 x 240 pixels at 24 bit/pixel). Performance varied according to the complexity of the images being transmitted. The 25 simultaneous users were supported without affecting the operation of the server and the system overhead was relatively small. The server's message-processing time and the network transmission delay amounted to 83 ms. The compression ratio of five previously stored video-sequences ranged from 336:1 to 1213:1. The underlying model for this system could serve a wide range of telemedicine and distance-learning applications.