Showing papers on "Run-length encoding published in 1992"

Arrangement and method of preprocessing binary picture data prior to run-length encoding

Abstract: An improved technique for pre-processing a picture image data signal wherein a black/white image data and a halftone image data coexists, is disclosed. The pre-processing is implemented before run-length encoding. Each of line image data signals is divided into n data blocks (n is a positive integer). A reset signal is produced in synchronism with each of the data blocks when divided. Following this, a selector is supplied with a first line image data signals directly applied and also receives the first line image data via a convolution circuit to said selector. The number of transition points in each of the data blocks is counted with respect to the first line image data signal which is directly applied to said selector. Similarly, the number of transition points in each of the blocks is carried out with the first line image data signal which is applied to said selector via said convolution circuit. The comparison results of n blocks of the first line image data are stored and then applied to the selector which chooses one of the data blocks of a second line image data signal applied thereto according to the comparison results. The second line image data signal is preceded by said first line image data signal.

Adaptive clumped dithering with clump plane separation

Abstract: A method is provided for data compression and image enhancement in a digital facsimile document transmission system. The method permits images containing gray scale content to be reproduced using conventional facsimile equipment. An irregularly shaped matrix of thresholds is employed in an adaptive approach to convert each multilevel gray scale pixel to a bilevel (black/white) pixel. The adaptive thresholding approach employed provides improved image quality in images containing both gray scale and high contrast information, e.g., identification cards. Compression performance is enhanced by an image rearrangement process in which pixels thresholded with similar threshold values are grouped together prior to run length encoding.

Image compression: wavelet-type transform along generalized scan

Abstract: An efficient method for visual data compression is presented, combining generalized Peano Scan, wavelet decomposition and adaptive sub-band coding technique. The Peano Scan which is an application of the Peano curve to the scanning of images, is incorporated with the encoding scheme in order to cluster highly correlated pixels. Using wavelet decomposition, an adaptive sub-band coding technique is developed to encode each sub-band separately with an optimum algorithm. Discrete Cosine Transform (DCT) is applied on the low spatial frequency sub-band, and high spatial frequency sub-bands are encoded using Run Length encoding technique.

Hardware-specific image compression techniques for the animation of CFD data

Abstract: The visualization and animation of computational fluid dynamics (CFD) data is vital in understanding the varied parameters that exist in the solution field. Scientists need accurate and efficient visualization techniques. The animation of CFD data is not only computationally expensive but also expensive in the allocation of memory, both RAM and disk. Preserving animations of the CFD data visualizations is useful, since recreation of the animation is expensive when dealing with extremely large data structures. Researchers of CFD data may wish to follow a particle trace over an experimental fuselage design, but are unable to retain the animation for efficient retrieval without rendering or consuming a considerable amount of disk space. The spatial image resolution is reduced from 1280 X 1024 to 512 X 480 in going from the workstation format to a video format, therefore, a desire to save these animations on disk results. Saving on disk allows the animation to maintain the spatial and intensity quality of the rendered image and allows the display of the animation at approximately 30 frames/sec, the standard video rate. The goal is to develop optimal image compression algorithms that allow visualization animations, captures as independent RGB images, to be recorded to tape or disk. If recorded to disk, the image sequence is compressed in non-realtime with a technique which allows subsequent decompression at approximately 30 frames/sec to simulate the temporal resolution of video. Initial compression is obtained through mapping RGB colors in each frame to a 12-bit colormap image. The colormap is animation sequence dependent and is created by histogramming the colors in the animation sequence and mapping those colors with relation to specific regions of the L*a*b* color coordinate system to take advantage of the uniform nature of the L*a*b* color system. Further compression is obtained by taking interframe differences, specifically comparing respective blocks between consecutive frames. If no change has occurred within a block a zero is recorded otherwise the entire block containing the 12-bit indices of the colormap is retained. The resulting block differences of the sequential frames in each segment will be saved after huffman coding and run length encoding. Playback of an animation will avoid much of the computations involved with rendering the original scene by decoding and loading the video RAM through the pixel bus. The algorithms will be written to take advantage of the systems hardware, specifically the Silicon Graphics VGX graphics adapter.

Combined wavelets-DCT image compression

Abstract: The mappings from multidimension to one dimension, or the inverse mappings, are theoretically described by space filling curves, i.e., Peano curves or Hilbert curves. The Peano Scan is an application of the Peano curve to the scanning of images, and it is used for analyzing, clustering, or compressing images, and for limiting the number of the colors used in an image. In this paper an efficient method for visual data compression is presented, combining generalized Peano Scan, wavelet decomposition, and adaptive subband coding technique. The Peano Scan is incorporated with the encoding scheme in order to cluster highly correlated pixels. Using wavelet decomposition, an adaptive subband coding technique is developed to encode each subband separately with an optimum algorithm. Discrete Cosine Transform (DCT) is applied on the low spatial frequency subband, and high spatial frequency subbands are encoded using Run Length encoding technique.

Apparatus for and method of preprocessing binary picture data prior to run-length encoding

Abstract: An improved technique for pre-processing a picture image data signal wherein a black/white image data and a halftone image data coexists, is disclosed. The pre-processing is implemented before run-length encoding. Each of line image data signals is divided into n data blocks (n is a positive integer). A reset signal is produced in synchronism with each of the data blocks when divided. Following this, a selector (42) is supplied with a first line image data signals directly applied and also receives the first line image data via a convolution circuit (36) to said selector. The number of transition points in each of the data blocks is counted with respect to the first line image data signal which is directly applied to said selector. Similarly, the number of transition points in each of the blocks is carried out with the first line image data signal which is applied to said selector via said convolution circuit. The comparison results of n blocks of the first line image data are stored and then applied to the selector which chooses one of the data blocks of a second line image data signal applied thereto according to the comparison results. The second line image data signal is preceded by said first line image data signal.

Data compression system in picture processor

Abstract: PURPOSE:To attain efficient data compression by applying the proper compression method to each bit plane when a picture data has a data structure of plural bits. CONSTITUTION:The picture processor consists of a picture data reader 101, a picture data processing system 102, a picture data compression expansion processor 103, an input interface 104, a data compressor 105, a transmission line 106, a page buffer 107, a picture data storage device 108, a data expander 109, and a picture output device 111 or the like. A picture data is divided into plural bit planes in this processor and a different data compression system is applied to each bit plane. That is, for example, the run length encoding system is applied to a high-order bit plane, and the prediction coding system having plural prediction devices corresponding to the bit frequency pattern is applied to the low-order bit plane.