Balancing High-Performance Parallelization and Accuracy in Canny Edge Detector

We present a novel approach to tradeoff accuracy against the degree of parallelization for the Canny edge detector, a well-known image-processing algorithm. At the heart of our method is a single toplevel image-slicing loop incorporated into the sequential algorithm to process image segments concurrently, a parallelization technique allowing for breaks in the computational continuity in order to achieve high performance levels. By using the fidelity slider, a new approximate computing concept that we introduce, the user can exercise full control over the desired balance between accuracy of the output and parallel performance. The practical value and strong scalability of the presented method is demonstrated by extensive benchmarks performed on three evaluation platforms, showing speedups of up to 7x for an accuracy of 100% and up to 19x for an accuracy of 99% over the sequential version, as recorded on an Intel Xeon platform with 14 cores and 28 hardware threads.