Design Of A Special-Purpose Computer For Locating Targets Within An Image

Abstract

Starloc (Sandia TARget LOcation Computer) is a special-purpose computer designed for target location in an image. It is based on a generalized correlation filter algorithm. Correlation of the input image and a small number (10-20) of specially-designed filter kernels is performed in the Fourier domain. The correlation of the input image with the filter set produces an encoding at each input image pixel location; targets are located at pixels with specific codes. This target signature is not sensitive to target variations such as rotation, range, brightness, and angle of view. Starloc is now under development and when completed will process two 256 pixel by 256 pixel input images per second. Starloc's basic architecture consists of ten pipelined processing stages (eight for Fast Fourier Transform operations and two for pixel by pixel operations) arranged in a ring-like structure. Within each stage are a controller, image memory, address generator, and register file with parallel floating-point processors. Starloc is designed to be fault tolerant by including two hot standby stages that can be switched into the data path when other stages fail and by incorporating a comprehensive set of error checkers. Using currently available floating-point processors, Starloc will run at a sustained rate of 188 MFLOPS (million floating-point operations per second). At this rate, it is performing 36 complex 256 pixel by 256 pixel two-dimensional Fast Fourier Transforms per second.