Joint compression and restoration of documents with bleed-through

This paper presents research on the digital restoration of scanned two-sided documents suffering from bleed-through, and the joint compression of the original document and its bleed-through corrected version. It is often required to have easy and efficient access to both the original docu-ment and the restored version. The method works simulta-neously on both the recto and the verso sides, and requires four steps: i) registration, ii) segmentation, iii) inpainting and iv) compression. The first step involves the registra-tion of the recto and the flipped verso so that bleed-though on one side will be aligned with the original information (called foreground) on the other side. An optimization method based on an affine transformation is used for this step. The second step requires segmentation of each side into four regions: ‘foreground only’, ‘background only’, ‘bleed-through only ’ and ‘mixed bleed-through and fore-ground’. Then, the areas identified as ‘bleed-through only’ are replaced with an estimate of the background using an inpainting technique. Finally the two-sided image is com-pressed for efficient storage and transmission. Each side is first compressed using any standard efficient document compression algorithm such as JPEG 2000. Then the seg-mentation information identifying the region ‘bleed-through only ’ on each side is compressed using a standard bilevel compression algorithm such as JBIG2. The information required to represent the inpainted sections must also be transmitted