Method for run-length encoding of a bitmap data stream

Details Method for run-length encoding of a bitmap data stream Method for run-length encoding of a bitmap data stream

2004-05-06

2010-02-02

Tran, Phuoc (Department: 2624)

Image analysis

Image compression or coding

Lossless compression

C382S166000

Reexamination Certificate

active

07657109

ABSTRACT:
Subtitling aims at the presentation of text information and graphical data, encoded as pixel bitmaps. The size of subtitle bitmaps may exceed video frame dimensions, so that only portions are displayed at a time. The bitmaps are a separate layer lying above the video, e.g. for synchronized video subtitles, animations and navigation menus, and therefore contain many transparent pixels. An advanced adaptation for bitmap encoding for HDTV, e.g. 1920×1280 pixels per frame as defined for the Blu-ray Disc Prerecorded format, providing optimized compression results for such subtitling bitmaps, is achieved by a four-stage run length encoding. Shorter or longer sequences of pixels of a preferred color, e.g. transparent, are encoded using the second or third shortest code words, while single pixels of different color are encoded using the shortest code words, and sequences of pixels of equal color use the third or fourth shortest code words.

REFERENCES:
patent: 5740278 (1998-04-01), Berger et al.
J. Jeong et al.: “Adaptive Huffman coding of 2-D DCT coefficients for image sequence compression”, Signal Processing, Image Communication, Elsevier Science Publishers, Amsterdam, NL, vol. 7, No. 1, Mar. 1, 1995, pp. 1-11.
T. von Roden: “H.261 and MPEG1-a comparison” Computers and Communications, 1996, Conference Proceedings of the 1996 IEEE Fifteenth Annual International Phoenix Conference on Scottsdale, AZ, USA, Mar. 27-29, 1996, pp. 65-71.
R. Llados-Bernaus et al: “Codeword assignment for fixed-length entropy coded video streams” Data Compression Conference, 1998, DCC'98 Proceedings Snowbird, UT, USA Mar. 30-Apr. 1, 1998, pp. 269-278.
Search Report Dated Sep. 15, 2004.

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