A fast segmentation algorithm for bi-level image compression using JBIG2

The emerging JBIG2 standard allows compliant encoders to achieve very high compression rates on bi-level images, especially when images are properly segmented into regions of line-art, halftones and text. We propose a fast method that is very effective at separating text from non-text regions, even when the regions are nonrectangular or have skew. Our method can also detect regions of reverse-coloured text. In most cases, our method increases the compression performance of the encoder. More importantly, our method can improve encoding speeds considerably, often by an order of magnitude