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A High-Compression Picture-Coding Algorithm for Photographic Videotex

Objective

The objective of the PICA project was to produce an efficient compression scheme for photographic images. The algorithm had to be capable of compressing a colour picture to 1 bit/pel or less while retaining good quality, allowing a full-frame videotex picture to be stored in only 32 Kbytes of memory and to be transmitted in 4 seconds on the Integrated Services Digital Network (ISDN). The final goal of the project was to gain acceptance of the algorithm as a standard.
The objective of the project was to produce an efficient compression scheme for photographic images. The algorithm had to be capable of compressing a colour picture to 1 bit/pixel or less while retaining good quality, allowing a full frame videotex picture to be stored in only 32 Kbytes of memory and to be transmitted in 4 s on the integrated services digital network (ISDN). The final goal of the project was to gain acceptance of the algorithm as a standard.

Innovative compression algorithms were developed and tested and then compared with known ones. Good results were achieved, with compression values meeting, and in some cases exceeding, the target of 1 bit/pel. Following the first year's work, a patent application was made for a new technique for vector quantization. British Telecommunications has been developing a new technique, known as recursive binary nesting, and a patent was filed during the second year.
Innovative compression algorithms were developed and tested and then compared with known ones. Good results were achieved, with compression values meeting, and in some cases exceeding, the target of 1 bit/pel. Following the first year's work, a patent application was made for a new technique for vector quantisation by CSELT. BT has been developing a new technique, known as Recursive Binary Nesting, and a patent was filed during the second year.
Exploitation
PICA submitted two compression algorithms to the ISO/CCITT Joint Photographic Experts Group (JPEG) for standardisation and one of them, the ADCT, was ranked first out of 12 during the first evaluation exercise. Early in 1988, the PICA project achieved itsgoal when ISO selected the PICA-ADCT algorithm for development into a standard.
Excellent results in terms of image quality were achieved using compression ratios of 21:1, and at 16:1 the decoded image is indistinguishable from the original except to the trained eye. At 64:1 the image can still be recognised and could be used, for example, for the quick scanning of photographic archives. The agreed high-compression technique should stimulate the market for photovideotex services in the 1990s.

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Coordinator

British Telecom plc (BT)
Address
British telecom laboratories martlesham heath
IP5 7RE Ipswich
United Kingdom

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EU contribution
€ 0,00

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Last update: 30 November 1992

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Permalink: https://cordis.europa.eu/project/id/1626

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