engleski

Acceleration of DCT transformation in JPEG image conversion

JPEG image format is one of the most commonly used image formats because of the high level of compression it provides and the fact that almost every web browser has a support for it. The algorithm that is based on CCITT Rec. T.81 (1992 E) poses no computational challenge when it is to be implemented on middle to large- scaled computer system but when considering small built-in computers, the traditional way of implementation has a very negative impact on performance. The major setback in this algorithm is the DCT frequency transformation of image data, the calculation of which is extremely CPU demanding and in case of low frequency cores, which are found in built-in systems, can take too much time to be carried out. This paper explores the alternatives to a standard software implementation of DCT transformation algorithm, an IEEE standard 1180 definition, and compares the obtained results on FPGA development boards such as Spartan-3E and Virtex-5 with 32-bit MicroBlaze™ soft-core processor. Three cases of implementation are presented: a software implementation of AAN algorithm, a special FPGA ip-core that accelerates the standard DCT algorithm and a special FPGA ip-core that implements the AAN algorithm. Both of the ip- cores work as coprocessor to a standard MicroBlaze processor.

DCT transformation ; JPEG ; image format

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