Paul G. Howard

Learn More
We present a new image compression technique called \DjVu " that is speci cally geared towards the compression of high-resolution, high-quality images of scanned documents in color. This enables fast transmission of document images over low-speed connections, while faithfully reproducing the visual aspect of the document, including color, fonts, pictures,(More)
The Joint Bi-level Image Experts Group (jbig), an international study group a liated with iso/iec and itu -t, is in the process of drafting a new standard for lossy and lossless compression of bi-level images. The new standard, informally referred to as jbig2, will support model-based coding for text and halftones to permit compression ratios up to three(More)
We provide a tutorial on arithmetic coding, showing how it provides nearly optimal data compression and how it can be matched with almost any probabilistic model. We indicate the main disadvantage of arithmetic coding, its slowness, and give the basis of a fast, space-e cient, approximate arithmetic coder with only minimal loss of compression e ciency. Our(More)
We present a method for both lossless and lossy compression of bilevel images that consist mostly of printed or typed text. The key feature of the method is soft pattern matching) a way of making use of the information in previously encountered characters without risking the introduction of character substitution errors. We can obtain lossless compression(More)
In this paper, we make a short foray through coding standards for still images and motion video. We first briefly discuss standards already in use, including: Group 3 and Group 4 for bilevel fax images; JPEG for still color images; and H.261, H.263, MPEG-1, and MPEG-2 for motion video. We then cover newly emerging standards such as JBIG1 and JBIG2 for(More)
DjVu is an image compression technique specifically geared towards the compression of scanned documents in color at high resolution. Typical magazine pages in color scanned at 300dpi are compressed to between 40 and 80 KB, or 5 to 10 times smaller than with JPEG for a similar level of subjective quality. The foreground layer, which contains the text and(More)
We give a detailed algorithm for fast text compression. Our algorithm, related to the PPM method, simpli es the modeling phase by eliminating the escape mechanism and speeds up coding by using a combination of quasi-arithmetic coding and Rice coding. We provide details of the use of quasi-arithmetic code tables, and analyze their compression performance.(More)
We present a new method for lossless image compression that gives compression comparable to JPEG lossless mode with about ve times the speed. Our method, called FELICS, is based on a novel use of two neighboring pixels for both prediction and error modeling. For coding we use single bits, adjusted binary codes, and Golomb or Rice codes. For the latter we(More)
Arithmetic coding, in conjunction with a suitable probabilistic model, can provide nearly optimal data compression. In this article we analyze the effect that the model and the particular implementation of arithmetic coding have on the code length obtained. Periodic scaling is often used in arithmetic coding implementations to reduce time and storage(More)