Showing papers on "Run-length encoding published in 1998"

RAPP: lossless image compression with runs of adaptive pixel patterns

Abstract: We propose a lossless compression technique specifically designed for palettized synthetic images. Predictive techniques no not work very well for these images, as a prediction "formula" based on some average of the values or palette indices of neighbors is not likely to be very meaningful. The proposed algorithm uses patterns of neighborhood pixels to predict and code each pixel. The prediction rules for different patterns are learned adaptively from the image itself. Using a large number of test images of the above kind (maps, clip-art, line drawings), the proposed method is found to reduce the size achieved by GIF compression by 50%, and the size resulting from the previous best approach (CALIC with optimized palette reordering) by 20%.

Method and apparatus for icon compression and decompression

Abstract: A method and apparatus for compressing and decompressing small amounts of image data, such as icon image data, is disclosed. The image data is transformed from RGB color space data to luminance and chrominance data. The chrominance data is then reduced by means of a thinning or averaging process. Run length encoding is performed on the luminance data and reduced chrominance data to compress for storage. The invention allows accurate and efficient storage and use of a small amount of compressed image data, particularly for continuous tone icons.

On-chip dynamic buffer level indicators for digital video encoder

Abstract: Method and encoder for encoding a digital video image stream. The encoding includes spatial compression of still images in the video stream and temporal compression between the still images. The spatial compression is carried out by converting a time domain image of a macroblock to a frequency domain image of the macroblock, taking the discrete cosine transform of the frequency domain image, transforming the discrete cosine transformed macroblock image by a quantization factor, and run length encoding the quantized discrete cosine transformed macroblock image. The temporal compression is carried out by reconstructing the run length encoded, quantized, discrete cosine transformed image of the macroblock, searching for a best match macroblock, and constructing a motion vector between them. This forms a bitstream of run length encoded, quantized, discrete cosine transform macroblocks and of motion vectors. This bitstream is passed to and through an external buffer to a transmission medium. The number encoded bits read by a host from the external buffer is fed back to the encoder for calculation in real time of a dynamic buffer level indicator indicative of the fullness of the external buffer. The encoder may generate a BUFFER — EMPTY flag, BUFFER — ALMOST — FULL flag and/or BUFFER — FULL flag for the host.

Parallel Run Length Encoding Compression: Reducing I/o in dYnamic Environmental Simulations

Abstract: Dynamic simulations based on time-varying inputs are extremely I/O intensive. This is shown by industrial appli cations generating environmental projections based on seasonal-to-interannual climate forecasts that have a compute to data access ratio of On leading to significant performance degradation. Exploitation of compression techniques such as run length encoding RLE signifi cantly reduces the I/O bottleneck and storage require ments. Unfortunately, traditional RLE algorithms do not perform well in a parallel vector platform such as the Cray architecture. This paper describes the design and imple mentation of a new RLE algorithm based on data chunking and packing that exploits the Cray gather-scatter vector hardware and multiple processors. This approach reduces I/O and file storage requirements on average by an order of magnitude. Data intensive applications such as the integration of environmental and global climate models now become practical in a realistic time frame.

Method and device for replacing part of digital encoding image

Abstract: PROBLEM TO BE SOLVED: To perform prescribed replacement even in the compressed pixel data of decoding images and to exclude the preparation of completely new sub images inside a memory by run length encoding the respective lines of images and occupying the same number of data units for the word of the run length encoding word of an image part for replacing an original image part to be replaced. SOLUTION: It is defined that a memory address for starting a replaceable area is known for the respective lines of a sub image unit. A processing program is provided with a function for retrieving a replaceable part. A reference number 40 is a first replaceable area, a numeral displayed in the figure corresponds to the 16-ary number of the run length encoding of a display character 0 and the reference number 41 indicates a second replaceable area. The areas 40 and 41 are replaced by a character for indicating the display character 2 for instance indicated at the lower part of the figure.

Halftoning method and apparatus

Abstract: The present invention relates to halftoning images for subsequent transmission. In particular, the invention is a halftoning method and system suitable for halftoning images which are to undergo run length encoding, such as in facsimile transmission. The invention processes the digital words to increase the number of pixels that are fully black and fully white. Then the invention error diffuses the pixels using error coefficients which govern the proportion of the error for each pixel that is distributed to other pixels on the same and following lines. The error coefficient for at least one of the pixels of the current line is reduced, and the error coefficient for at least one of the pixels of the next following line is increased, such that should the error diffused pixels be compressed by run length encoding (where a run of identical symbols is replaced by a symbol and a count) the efficiency of the compression is improved.