Pipeline algorithm of regional labeling based on simultaneous unification of two rows labels

This paper presents a new regional labeling algorithm version based on raster-scan pipeline processing. It is aimed at a hardware implementation that can continuously process images at TV video rates. First, the author describes the (previously reported) fundamental algorithm. The characteristic of the algorithm is that when it writes labels on pixels of the current row, it always renews labels of the immediately preceding row while raster scanning and that it unifies the label linkage information at every row. He discusses the problem of when this row-by-row unification has to be done. As a solution, he proposes a new version that writes labels on two rows at every two rows. This can save enough time for the subunification of emergent two rows labels. Thus, it takes O(n) time for the total label unification after the final row of the input image, where n is the whole number of the labels. He also includes a fast subunification method without label sorting