Abstract: A printer driver software product is provided for execution by a computer to produce compressed page data corresponding to a page layout. The driver includes instructions to generate continuous-tone data and bi-level text and black graphics data from print data corresponding to the page layout. Data compression instructions are also included in the printer driver. Upon execution the data compression instructions cause the computer to compress the set of continuous-tone data and the set of bi-level text and black graphics data to produce compressed page data corresponding to the page layout. The compressed data is then transmitted to a printer in communication with the computer. A printer driver software product according to the invention is particularly useful where a printer is coupled to a computer by means of a relatively limited bandwidth connection.

Abstract: A method for serving an image from a server to a client, e.g., a computer having a browser or other graphics viewing engine. The user of the client first specifies a set of one or more bitmap characteristics for an image transfer, with at least one of the bitmap characteristics including a number of bits per pixel. Preferably, this specification is accomplished using an applet or other piece of code that is downloaded to the client from the server. Later, when the server receives a client request that includes data identifying a specified bitmap characteristic, a server processing routine (e.g., a servlet) generates a version of the image that conforms to the specified bitmap characteristic. This version is then delivered back to the client in response to the original request. In this way, the user of the client machine can control the particular characteristics of the image files that are delivered to his or her machine.

Abstract: In a digital signal processing system, a method for selecting a transform function to apply to an input signal based on characteristics of the signal, and for self-adjusting criteria which are used in selecting a transform function to apply to a subsequent signal. Characteristics are obtained from the signal. The characteristics are compared to adjustable criteria which are used in selecting a transform function. Differing criteria are maintained for the different selectable transform functions. A record is maintained of transform functions selected and the particular characteristics that caused the selection. Based on the ability of a transform function to minimally define the coded signal, an inverse transform function is selected to decode the signal. The criteria used in selecting a transform function to apply to a subsequent signal are adjusted based on a quality measure of the decoded signal and the record of selected transform functions.

Abstract: A system and method for accepting raster data from a Postscript or equivalent image data generator, identifying portions of the raster image which contain continuous tone data and linework data, dividing those portions into separate tiles and compressing the data within each tile by a compression method optimized for the type of image data within the tile. The compression algorithms are based upon conventional JPEG or LZW techniques, but enhanced to more efficiently process image data sets with large amounts of blank data.

Abstract: A data compression system is provided in accordance with the present invention. The system includes a scanning component which scans at least a portion of a transformed image. The scan is performed substantially in a horizontal direction on a first section of the portion and in a vertical direction on a second section of the portion to enable improved data compression of the transformed image. The horizontal and vertical scan directions are performed via a contiguous scan of the respective sections to further enable improved data compression of the transformed image.

Abstract: Methods and apparatus for generating a compressed image from a source image by compressing the source image using a dictionary based lossy compression algorithm that regionally varies the amount of information loss from the source image based on regional image quality levels contained in an image quality mask. The image quality mask can be an alpha channel of the source image, can be stored as a raster map, or can be stored as a resolution independent function. The regional image quality levels in the image quality mask can be determined by a user, automatically generated from the image, or automatically generated from user input. The dictionary based lossy compression algorithm can be a lossy Lempel-Ziv-Welch (LZW) compression algorithm.

Abstract: The image processing apparatus transforms orthogonal transform coefficients into a predetermined number of bits for each spatial frequency, rearranges quantized data for each spatial frequency to an arrangement with spatial frequency band portions, thereby generates bit serial data that the quantized data of the same spatial frequency band exists successively over adjacent blocks, and compresses the bit serial data.

Abstract: The present invention efficiently compresses image data, and stores and manages the compressed data. Image data is compressed in tile unit having predetermined pixels and data packing is performed. The compressed data is compared with compressed data of a preceding packet. If these compressed data are different, the packet data is stored in a memory, and an entry address of the compressed data is stored in a packet table. Meanwhile, if the compressed data is equal to the compressed data of the preceding packet, the compressed data is not stored, but an entry address of the compressed data of the preceding packet is stored in a record of interest in the packet table, and a flag indicative of repetition of the preceding address is set in the packet of interest.

Abstract: A method and system of reducing the computation load of an MPEG decoder by changing the encoding algorithms in a video-processing system are provided. During an encoding mode, a stream of data blocks is received and at least one motion vector and one motion compensation prediction value for each macro-block are generated. The prediction value is transformed into a set of DCT coefficients. Prior to the quantizing step, the set of DCT coefficients are modified according to predetermined criteria. To this end, the total energy level of the DCT coefficients excluding the lowest 2×2 DCT coefficients is computed, and last column and last row of the DCT coefficients is discarded alternatively until the total energy level of the DCT coefficients reaches a predetermined energy level. Therafter, the discarded column or row is assigned to a predetermined value.

Abstract: A method and apparatus for coding and decoding information is described. In one embodiment, the apparatus comprises a memory and decoding hardware. The memory stores run counts and/or skip counts and the decoding hardware decodes a run count and/or a skip count obtained from the memory during decoding.

Abstract: A method of image compression comprises the steps of recursively transforming a image using a Discrete Wavelet Transform. This creates a plurality of levels including at least a first level, multiple intermediate levels, and a low-low pass subband of the last level. The transformed image at each level is quantized, and datapacking the quantized image is performed. The step of datapacking further includes, encoding of the first level using adaptive run length of zero cofficients; encoding of the intermediate levels using run-length coding of zero coefficients and a predetermined two-knob huffman table for non-zero coefficients and encoding of the low-low pass subband using a low frequency packing algorithm.

Abstract: A data compression system is provided in accordance with the present invention. The system includes a scanning component which scans at least a portion of a transformed image. The scan is performed substantially in a horizontal direction on a first section of the portion and in a vertical direction on a second section of the portion to enable improved data compression of the transformed image. The horizontal and vertical scan directions are performed via a contiguous scan of the respective sections to further enable improved data compression of the transformed image.

Abstract: The present invention includes a system, method, and article of manufacture for decompressing a bit stream of compressed data representing a plurality of image blocks. This includes a two-step method of processing both a DC code and a plurality of AC codes. With respect to the processing of the AC codes, a plurality of bits of compressed input data relating to the AC codes are first retrieved from the bit stream. A first decoding operation is then executed based on the obtained compressed input data in order to generate first output data. It is then determined whether sufficient space is available for the first output data. If it is determined that there is sufficient space for the first output data, the first output data is outputted. On the other hand, if it is determined that there is insufficient space for the first output data, an alternate second decoding operation is executed in order to generate second output data.

Abstract: Images are to be efficiently and easily encoded while suppressing block distortion and pseudo-contour generation. A quantization characteristics determining unit receives pixel values from a pixel value input unit, measures the length S of the consecutive occurrence of the same pixel values in connection with a pixel to be encoded and the pixel value differences D, and determines quantization characteristics n with reference to the result of sensory evaluation. A quantization/inverse quantization unit quantizes pixel values to be inputted with the quantization characteristics n, and further inverse quantizes them to reduce the number of gray-scale levels. The output pixel values of the quantization/inverse quantization unit are encoded and outputted by an entropy encoding unit.

Abstract: JPEG data is efficiently recompressed and transmitted to a remote color facsimile device. Before transmission of recompressed JPEG data, an anticipated transmission time is displayed for enabling the user to easily select the desired compression ratio. To generate recompressed JPEG, a Huffman decoder is provided for decoding encoded data and temporarily generates decoded data. Table generator multiplies the predefined quantization table values by the prescribed value to generate the modified quantization table. Intermediate data generator generates the intermediate data by dividing the encoded data by ratio n, which is derived by dividing predefined quantization table by the modified quantization table. Huffman encoder encodes the intermediate data to create new encoded data. Recompressed JPEG data includes the newly coded data and the modified quantization table.

Abstract: A multi-layer embedded bitstream is generated from a subband decomposition by partitioning each subband of the decomposition into a plurality of blocks; and encoding the blocks of each subband. The blocks of each subband are coded independently of each other. Resulting is a block bitstream corresponding to each block. Truncation points may be identified on the block bitstreams, and selected portions of the block bitstreams may be concatenated, layer-by-layer, to form the single-layer or multi-layer bitstream. Syntax information may also be added to the multi-layer bitstream. An image can be reconstructed from the embedded bitstream at a desired bit-rate or resolution by reading the syntax information, randomly accessing desired portions of the block bitstreams, decoding the randomly accessed portions, dequantizing the decoded portions, and applying an inverse transform to the dequantized portions.

Abstract: A vertical HPF and a horizontal HPF receive a video signal 101, and extract only a high frequency component in the vertical/horizontal directions, respectively. Absolute value taking parts take an absolute value of the high frequency components, respectively, and change their values to positive values. A horizontal accumulating/adding part and a vertical accumulating/adding part accumulate/add an input signal so as to output a vertical one-dimensional signal and a horizontal one-dimensional signal, respectively, each periodically having a peak value in the respective vertical and horizontal directions. A horizontal peak detecting part detects a horizontal peak position according to the horizontal one-dimensional signal. A vertical peak detecting part detects a vertical peak position according to the vertical one-dimensional signal and identifies a format thereof.

Abstract: A method of quantizing multiple input values in parallel using SIMD instructions is disclosed. In one embodiment, the method comprises (1) receiving a set of input values Xi; (2) operating on the set of input values to produce a set of binary mask values Ki that are related to the input values Xi by Ki=−1 if Xi>0, and Ki=0 if Xi<0; (3) adding half of a quantization step Q to the input values Xi to obtain sum values; (4) subtracting half of a quantization step Q to the input values Xi to obtain difference values; (5) using the binary mask values to screen out sum values calculated from negative input values; (6) using a complementary binary mask to screen out difference values calculated from positive input values; and (7) combining the screened sum and difference values to determine prequantization values Yi that can be expressed Yi=Xi+Q/2 if Xi>0, and Yi=Xi−Q/2 if Xi≦0.

Abstract: In a digital signal processing system, a method for selecting a transform function to apply to an input signal based on characteristics of the signal, and for self-adjusting criteria which are used in selecting a transform function to apply to a subsequent signal. Characteristics are obtained from the signal. The characteristics are compared to adjustable criteria which are used in selecting a transform function. Differing criteria are maintained for the different selectable transform functions. A record is maintained of transform functions selected and the particular characteristics that caused the selection. Based on the ability of a transform function to minimally define the coded signal, an inverse transform function is selected to decode the signal. The criteria used in selecting a transform function to apply to a subsequent signal are adjusted based on a quality measure of the decoded signal and the record of selected transform functions.

Abstract: Compression apparatus is described that operates to select an optimum compression procedure to apply to received image data. The compression apparatus can be employed in a page printer having a print engine that must be provided with video data at a constant rate in order to avoid a print underrun. The page printer operates to receive print data and to convert the received print data into rasterized page strips. Some or all of these rasteized page strips can then be compressed by the compression apparatus for later conversion to video data. The compression apparatus operates to compress each received rasterized page strip by selecting a compression procedure that results in a compressed strip that will provide optimum print quality while not causing a print underrun and that is below a threshold data size.

Abstract: A method for losslessly transmitting data is provided. The data is separated into two or more portions and the second portion is subtracted from the first portion to find a difference. The first portion and the difference are transmitted, and then the second portion is reconstructed by adding the difference to the first portion. The data may comprise two or more images, with each image being a temporally displaced version of the preceding image. Each image may be divided into multiple areas, where the areas on each image correspond to the areas on the other images. A difference may be obtained by subtracting each area of an image from the corresponding area of the preceding image. The first image may then be transferred as a reference image along with the differences, and each image may be reconstructed by adding each difference to the corresponding area of the previous image.