Fast peak autocorrelation finding for periodicity-exploiting compression methods

Summary form only given. Bilevel image compression algorithms like JBIG, JBIG2-Generic, and PRECIS can exploit 1D or 2D peak autocorrelation in binary images like 'digital halftones', in order to achieve breakthrough boosts in additional compression. For hard to compress, but periodic halftones, boosts of factors of three or more times the compression ratios and similar increases in decompression speeds can be achieved (boosts defined v.s. the closest related, non-periodicity-exploiting algorithm (e.g. JBIG or JBIG2-Generic with AT>0 v.s. with AT=O, or PRECIS v.s. MMR)). Our peak autocorrelation finding method isolates the needed period for peak compression, two orders-of-magnitude faster than the prior art.