A flexible ASIP architecture for connected components labeling in embedded vision applications

Real-time identification of connected regions of pixels in large (e.g. FullHD) frames is a mandatory and expensive step in many computer vision applications that are becoming increasingly popular in embedded mobile devices such as smart-phones, tablets and head mounted devices. Standard off-the-shelf embedded processors are not yet able to cope with the performance/flexibility trade-offs required by such applications. Therefore, in this work we present an Application Specific Instruction Set Processor (ASIP) tailored to concurrently execute thresholding, connected components labeling and basic feature extraction of image frames. The proposed architecture is capable to cope with frame complexities ranging from QCIF to FullHD frames with 1 to 4 bytes-per-pixel formats, while achieving an average frame rate of 30 frames-per-second (fps). Synthesis was performed for a standard 65nm CMOS library, obtaining an operating frequency of 350MHz and 2.1mm² area. Moreover, evaluations were conducted both on typical and synthetic data sets, in order to thoroughly assess the achievable performance. Finally, an entire planar-marker based augmented reality application was developed and simulated for the ASIP.