We present a novel mixed-signal VLSI focal-plane array processor performing the morphological
operation of skeletonization of binary images at a processing speed of up to 10K frames/second.
The chip exploits the inherent parallelism of the grassfire algorithm by using a massively
parallel mixed-mode array achieving high computational speed and low power consumption.
The system is a two-dimensional array of identical processing elements (PEs) with
integrated photodetectors allowing parallel optical input. The skeleton computation
is performed in a fully parallel, asynchronous manner by local interactions between
PEs, the transformed image is represented by analog values. The output of the transformation
can be serially accessed with an on-chip raster-scan circuit generating multiscanning-compatible
video signal. The system was physically designed and prototypes of 22x26 array were
fabricated in a standard 0.7 µm CMOS process. Circuit and layout design considerations
as well as output data samples of the fully functional fabricated chip are presented.
