Segmentation of scanned documents for efficient compression

A scanned, complex document image may be composed of text, graphics, halftones, and pictures, whose layout is unknown. In this paper, we propose a novel segmentation scheme for scanned document images that facilitates their efficient compression. Our scheme segments an input image into binarizable components and non-binarizable components. By a binarizable component we mean that the region can be represented by no more than two gray levels (or colors) with acceptable perceptual quality. A non-binarizable component is defined as a region that has to be represented by more than two gray levels (or colors) with acceptable perceptual quality. Once the components are identified, the binarizable components can be thresholded and compressed as a binary image using an efficient binary encoding scheme together with the gray values represented by the black and white pixels of the binary image. The non-binarizable components can be compressed using another suitable encoding scheme.