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A Foveated Retina for the Robot Eye

M. Bolduc, M.D. Levine. [bolducar.ps].95 Data reduction with a foveated retina: (a) input video image (532 by 484 pixels), (b) foveated image in the image plane demonstrating the non-uniform data reduction scheme, (c) output images produced by the Foveated Retina System representing the foveated image in the cortical plane (13981 pixels in total). levine:bolduc The design of a vision system for autonomous robotics produces conflicting requirements. High resolution in the image is needed to obtain the necessary details in the local region of interest. But a wide field-of-view is also useful to detect events in the larger environment. For a uniform sensor, these entail a very large amount of image data, which in turn requires a large amount of processing time. However, to ensure adequate response time from the robot vision system, processing time must be kept at a minimum. A good compromise between the resolution, field-of-view, and processing time requirements is to develop a camera system based on models of image data reduction of the primate retina. These non-uniform image sampling models effectively divide the retina into foveal and peripheral regions. The fovea is located at the center of the retina and contains image data at the highest possible resolution. In the periphery, the image information is compressed at a scale which varies inversely with the distance from the center of the fovea. This arrangement permits sensing a high level of detail in the area about the point of retinal fixation. At the same time it also gives coarse information about events in a large area around the center of attention without the cost of processing an extraneous amount of data. An electronic retina (CCD camera with uniform resolution) is used as the input device. The foveation process is achieved by employing an adaptation of a raster-scan algorithm implemented on a network of parallel processing modules based on the Texas Instruments TMS320C40 DSP. As output, the system provides foveal and the peripheral images which can be fed directly to another processing system for further computation. These images can be produced at a speed of at least 10 frames per second. The robot eye will be mounted on a specially designed miniature computer-controlled pan/tilt mechanism.


next up previous contents
Next: A Real-Time Attentional Mechanism Up: Sensor and Processor Design Previous: High Speed Miniature Orienting

Thierry Baron
Mon Apr 7 12:54:24 EDT 1997