Digipaper: A Versatile Color Document Image Representation

We describe a segmentation method and associated file format for storing images of color documents. We separate each page of the document into three layers, containing the background (usually one or more photographic images), the text, and the color of the text. Each of these layers has different properties, making it desirable to use different compression methods to represent the three layers. The background layers are compressed using any method designed for photographic images, the text layers are compressed using a token-based representation, and the text color layers are compressed by augmenting the representation used for the text layers. We also describe an algorithm for segmenting images into these three layers. This representation and algorithm can produce very highly-compressed document files that nonetheless retain excellent image quality.