The main purpose of this thesis is to develop an efficient near-lossless bitonal compression algorithm and to implement that algorithm on a hardware platform. The current methods for compression of bitonal images include the JBIG and JBIG2 algorithms, however both JBIG and JBIG2 have their disadvantages. Both of these algorithms are covered by patents filed by IBM, making them costly to implement commercially. Also, JBIG only provides means for lossless compression while JBIG2 provides lossy methods only for document-type images. For these reasons a new method for introducing loss and controlling this loss to sustain quality is developed. The lossless bitonal image compression algorithm used for this thesis is called Block Arithmetic Coder for Image Compression (BACIC), which can efficiently compress bitonal images. In this thesis, loss is introduced for cases where better compression efficiency is needed. However, introducing loss in bitonal images is especially difficult, because pixels undergo such a drastic change, either from white to black or black to white. Such pixel flipping introduces salt and pepper noise, which can be very distracting when viewing an image. Two methods are used in combination to control the visual distortion introduced into the image. The first is to keep track of the error created by the flipping of pixels, and using this error to decide whether flipping another pixel will cause the visual distortion to exceed a predefined threshold. The second method is region of interest consideration. In this method, lower loss or no loss is introduced into the important parts of an image, and higher loss is introduced into the less important parts. This allows for a good quality image while increasing the compression efficiency. Also, the ability of BACIC to compress grayscale images is studied and BACICm, a multiplanar BACIC algorithm, is created. A hardware implementation of the BACIC lossless bitonal image compression algorithm is also designed. The hardware implementation is done using VHDL targeting a Xilinx FPGA, which is very useful, because of its flexibility. The programmed FPGA could be included in a product of the facsimile or printing industry to handle the compression or decompression internal to the unit, giving it an advantage in the marketplace.
Library of Congress Subject Headings
Image compression; Image processing--Digital techniques; Imaging systems--Image quality; VHDL (Computer hardware description language); Field programmable gate arrays
Computer Engineering (MS)
Department, Program, or Center
Computer Engineering (KGCOE)
Pyle, Jeremy, "Near-Lossless Bitonal Image Compression System" (2003). Thesis. Rochester Institute of Technology. Accessed from
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