Modern medical imaging devices

such as CT and MRI

can provide detailed data representations of the interior of the human body. Realistic volume rendering incorporates Monte Carlo path-tracing algorithm

which addresses the visualization of these data to provide photorealistic images. However

Monte Carlo path-tracing volume rendering demands high storage volume and computational power. Therefore

it can only be interactively visualized on clusters with installed high-performance GPU. Current mobile devices

such as smart phones and tablets

significantly contribute to mobile computing. The realistic volume rendering of high-volume datasets at interactive update rates is still computationally expensive for current hand-held devices because of the limitations of computational capability and power consumption. Remote rendering helps address this issue by running heavy-volume rendering computation on a powerful GPU-accelerated server and transmitting the rendering results to the mobile client for display and interaction. A volume renderer that utilizes Monte Carlo path-tracing (MCPT) techniques was set up to progressively generate realistic images. A dedicated web server sent rendering results to and received user inputs from mobile devices. Renderer servers can produce rendered images at a high updating rate

whereas web server streams render images at a slower rate than a renderer server

particularly when network conditions are poor. Low rendering efficiency is caused by unbalanced data transmission and processing rate between renderer servers and web servers. This paper introduced optimized coupling and performance between a graphic server and web server to improve rendering efficiency and maintain system interactivity. The coupling algorithm can balance the output speed of renderer servers and transfer speed of web servers by adaptively adjusting the rendering iterations of each output image and keeping renderer servers busy before completing rendering tasks. To directly compare the performance of the coupling algorithm with that of a connected volume renderer server with web server

we set up an experiment that recorded the total frames received by browsers and the duration of the entire rendering process after user interaction was terminated. The experiment utilized Manix

Mecanix

VisMale

and Bonsai volume datasets. Experimental results indicated that using the coupling algorithm between renderer servers and web servers significantly reduced the time required to achieve the final high-quality image

unlike the direct connection between renderer servers and web servers. The results also revealed that the renderer server connects with web servers via the coupling algorithm

which allows end users to obtain the final high quality image in nearly the same amount of time

regardless of network condition. Web-based realistic remote volume rendering system is proposed to provide end users with access to high-performance rendering services using any HTML5 supported device. The coupling algorithm that links renderers and Web servers can adjust the output speed of the renderer depending on the overall capacity of a network while maintaining the performance of the renderer. Thus

end users quickly obtain the final rendered images.