A Single-Pass Connected Component Labeler without Label Merging Period

Abstract

In this paper, for real-time multi-channel video analytics, an architecture of a single-pass connected component labeler without label merging period is proposed; this structure can handle multiple video channels from incoming video signals or from memory. During the line scan period, after determining an event based on the 8-connectivity check of incoming pixels, an 8-connectivity checker notifies all the label registers inside a label shift register of the event and the control signals for label handling. Each label register takes a label input either normally from the shifted label in the label shift register, or from the merging label without additional cycles for the label merging event. A label stack is designed for efficient label allocation with label reuse. An information extractor calculates bounding boxes and centers of gravity for labeled objects using the information from the 8-connectivity checker and the pixel counter. The proposed architecture is finally implemented on a field programmable gate array (FPGA) device, integrated into a video analytics system, and verified as to its functions and performance. More than 28 % of the memory usage by conventional architectures is reduced in the proposed architecture for the same maximum number of labels in video surveillance environments.