<title>Document image compression using document analysis and block-class-specific data compression methods</title>

Abstract

The huge amount of storage needed for document images is a major hindrance to widespread use of document image processing (DIP) systems. Although current DIP systems store document images in compressed form, there is much room for improvement. In this paper, a nearly-lossless document image compression method is investigated which preserves the relevant information of a document. The proposed approach is based on the segmentation of a document image into different blocks that are classified into one of several block classes and compressed by a block-class-specific (BCS) data compression method. Whereas image and graphics blocks are compressed using standard image compression methods, text blocks are fed into a text and font recognition module and converted into their textual representation. Finally, text blocks are compressed by encoding their textual representation and enough formatting information to be able to render them as faithfully as possible to the original document.Preliminary results show that ( 1) the achievable compression ratios compare favourably with standard document image compression methods for all document images tested and (2) the quality of the decompressed image depends on the recognition accuracy of the text recognition module.

An Efficient Image Compression Scheme for Air Tickets Storage

“…Here we don't include the size of background image, because it can be omitted for batch same type images 'compression. See (3).…”

“…The degree of separation will affect the compression rate and decompression quality. Here we adopt a simple and fast threshold segmentation method NiBlack [3] .…”

“…Because such coupon images have special characteristics different from nature photographic image, so many special methods have been developed for higher compression rate. Huang Jincheng improved a methods based on layered coding [4] and Rene Sennhauser brought forward block-classspecific document analysis and compression method [3] . In JPEG 2000 standard part 6 also gives a coding system for compound document image [11] .…”