Abstract: A finite state machine is implemented by encapsulating the portions of a state table, which are associated with each state in a state object. Each state object is instantiated when the associated state is entered and destroyed when the state is exited. Since memory is only allocated at runtime when an object is instantiated and in existence, the amount of memory required to implement the state table is minimized. The state class from which the state object is instantiated can be subclassed. In accordance with normal object-oriented class design, a subclass inherits the state table of its parent class. However, the subclass allows table rows to be added and table rows present in the parent class to be overwritten in the subclass. The state table in each state class includes methods that are called when the class is created and destroyed.

Abstract: A method of and apparatus for performing blitter operations is performed in two parts. First, a description of the to-be-performed data transfer is analyzed and a computer instruction sequence is generated therefrom. The instruction sequence may include the appropriate instructions to implement scaling, clipping, and color conversion of a source image, as implicated by the blitter description. Second, the computer instruction sequence is executed an appropriate number of times, again depending upon the blitter description. One of the described embodiments transforms a blitter description that describes a target image in terms of visible rectangles into a description that describes the target image as having at least one line-type, in which the line-type comprises at least one pixel run, characterized by visible and non-visible states. The line-type description is then utilized by a code-generating logic to generate the appropriate instructions.

Abstract: A technique for initiating communications from a web browser to a destination on either a packet-switched data network or a circuit-switched communication network includes a communication utility capable of interacting with a browser utility and responsive to address information obtained from a website for establishing a communication link with the website with the other destination defined by the address information. In one embodiment, the address information may comprise either an Internet protocol address, an E-mail address, or a traditional telephone number. The communication utility further enables sharing of URL data so that once a communication link is established, the parties may examine the same website pages simultaneously while communicating over a point-to-point communication link.

Abstract: An digital video image processing system employs codes of various lengths to encode the luminance information within the digital video images. The inventive method and apparatus divides a video image into non-overlapping regions containing a plurality of pixels with luminance values. Within each region, the method computes the total luminance variation across the region, the direction of greatest luminance change within the region, the base, or lowest, luminance value within the region and the location and type of luminance transition within the region. Depending on the variation of the luminance values within a region and on the quality desired in the decoded image, the computed information is used to encode the luminance values in short, medium, or long codes. The luminance codes may be predetermined and unchanging or they may vary from image to image or within given images.

Abstract: An digital video image processing system employs codes of various lengths to encode the luminance information within the digital video images. The inventive method and apparatus divides a video image into non-overlapping regions containing a plurality of pixels with luminance values. Within each region, the method computes the total luminance variation across the region, the direction of greatest luminance change within the region, the base, or lowest, luminance value within the region and the location and type of luminance transition within the region. Depending on the variation of the luminance values within a region and on the quality desired in the decoded image, the computed information is used to encode the luminance values in short, medium, or long codes. The luminance codes may be predetermined and unchanging or they may vary from image to image or within given images.

Abstract: Disclosed is a system and a method for compressing digitized color video data by generating codes into a pattern of tables for regions in frames of the video data exhibiting certain patterns. An image frame in a video data stream has a plurality of pixels assigned digitized color and luminance data. The image frame is divided into a plurality of non-overlapping elementary units, with each elementary unit comprising a plurality of pixels. For elementary units exhibiting change from the prior frame in time, elementary units having pixels with differing digitized color and luminance data are selected for pattern matching. Each pixel of an elementary unit selected for pattern matching is mapped to a pattern value. A pattern value is the same for all pixels sharing the same color and luminance data in an elementary unit. The pattern values are then grouped based on relative position in the elementary unit into offsets into associated sets of pattern match tables and error condition tables.

Abstract: An image-compression/decompression system employs a variable spatial-frequency encoder to encode the chrominance information contained within a video image. The system divides the video image into non-overlapping regions and partitions each region into sub-regions. Within each region, the system computes a weighted average of the chrominance values in each sub-region, and compares the weighted average value associated with each sub-region to the weighted average values associated with the other sub-regions within the region. If differences between the average values are less than a predetermined threshold amount, the system assigns a single chrominance encoded value to the entire region. If, on the other hand, the differences between the weighted average values is more than the predetermined threshold amount, the system assigns individual chrominance values to each of the sub-regions.

Abstract: A personal computer system has source of input video data containing digitized pixel color values, and a display operated with palette quantized colors including non-linear palette quantized colors. A conversion table is stored in the system for converting blocks of pixel color values into palette colors, the conversion table comprising a plurality of error diffusion arrays covering the color range of pixel color values. Each array in the conversion table corresponds to a different color value, each array being accessed using said corresponding color value as an index into said table. Each array in the table has "n" fields respectively containing palette color values ordered in accordance with an order matrix by sorted luminance values.

Abstract: Systems and methods that enable digital video compression techniques to manage and control artifact presence in each compressed frame of the video clip. Wherein specific embodiments are applicable to interframe and intraframe video compression methods and can be used in the compression of digital images and digital video clips. Other embodiments are employable in digital video compression and are applicable to interframe compression methods. A mechanism to increase the amount of video compression, while maintaining video quality that may otherwise be sacrificed with such increases in video compression, by threshold value management to accommodate the human eye's ability to more readily discern local image features or artifacts at central image locations or focused-upon areas, while tolerating, to a greater extent, artifacts dispersed elsewhere in the image.

Abstract: Hybrid compression processes for digital color video data that enables software only playback of the compressed digital video in low-end computers, wherein intraframe and interframe compression techniques are brought together through a sequence of procedures that analyze local frame regions, integrate unique processes with block truncation coding compression, and adopt the advantages of visual pattern image coding for color video. The process determines the appropriate encoding of each local frame region with one of various compression techniques, based upon its image properties. The compression methods retain the fidelity of the original video data to provide high quality video during decompression and reconstruction of high motion and textured video clips, while simultaneously providing sufficient compression and ease of decoding for software-only decompression thereby exhibiting properties that enable good quality video to be displayed in low-end computers.

Abstract: A system and method of compressing original video data expressed in a plurality of digitally coded frames which enable decompression and playback of resulting compressed video data at one of a plurality of frame rates while maintaining temporal fidelity of the frames displayed. Compression includes selecting a plurality of rate streams for the compressed video data, including a highest rate stream including all of the frames of the original video data and a lowest rate stream including a subset of regularly spaced frames of the original video data. Then the initial frame in the original video data is spatially compressed and the resulting compressed data placed in the compressed video data. The initial frame is also saved as a base frame for all rate streams for subsequent temporal compression of the original video data.

Abstract: A frame-differencing based method for coding and decoding color video data suitable for real-time, software-only based decompression and playback in low-end personal computers wherein the computational demands required of a computer microprocessor to implement the method are readily met by microprocessors such as an Intel 80386SX microprocessor running at 16 Mhz. Frame-to-frame differences are detected in a manner analogous to human perception of luminance data, rather than by the differences in the actual numerical video data. This permits greater compression of data without added computational complexity to the decompression process. Image analysis techniques are employed to ameliorate the appearance of the video. A lossless coding method that unifies two separate compressed data entities is used to obtain a greater amount of compression and simultaneously to reduce the computational complexity of the decompression process.

Abstract: A method of quantitatively measuring fidelity of a reproduced image reconstructed from a compressed data representation of an original image is disclosed. The method comprises, responsive to user selection, for establishing a global assessment mode or a local assessment mode. In the global assessment mode changes in luminance of the reproduced image from the original image and changes in color in first and second color difference values of the reproduced image from the original image are used score fidelity. Changes in luminance are measured using a dynamic range, nonlinear transform equation. In the local assessment mode, and responsive to user selection, the reproduced image and the original image are segmented and corresponding pairs of segments from the reproduced image and the original image are identified. Scoring of fidelity of the reproduced image to the original image is done by comparing corresponding pairs of segments in color, luminance, shape, displacement and texture.

Abstract: A personal computer system is operated to concurrently execute threads of multitasking operations to capture motion video data from a video source, compress such data, and record the compressed data in a file. Compression is selectively done in either one of two modes, an inter-frame compression mode and a intra-frame compression mode, both modes being block-oriented. During intra-frame compression, homogenous blocks are used to represent four pixel values with a single pixel value when the four pixels in a block are perceptually similar. During inter-frame compression, unchanged blocks are used to represent four pixel values as unchanged from the preceding frame when the four pixels are perceptually similar to the same four pixels in the preceding frame.

Abstract: Decompression of video segments from a sequence of differential frames is done by selected scaling of frame resolution and color depth. A frame header indicates the computational complexity of decompression of a frame, allowing selection of scales for output resolution and color depth. Decompression proceeds by retrieving a frame from the compressed video stream in elementary units. An elementary unit is characterized by types, including an unchanged type, a homogeneous type, a pattern type and a predetermined pattern type. For a retrieved elementary unit of the unchanged type, an output pointer to a display buffer is moved by an elementary unit scaled by the output resolution scale. For a retrieved elementary unit of the homogeneous type, a color retrieved from the compressed video stream is applied to an area in the display buffer corresponding to an elementary unit scaled by the output resolution scale.

Abstract: A process for coding a plurality of compressed video data streams in a time ordered sequence. Each compressed data stream includes coding of frame to frame differences of a video segment, which are represented as a compressed M.times.N exclusive-OR plane of pixel change values and location displacement control values for an output pointer into a decompressed video frame. By coding frame to frame differences in an exclusive-OR values, the replay process is made bidirectional, allowing for both forward and reverse playback of the video segment.

Abstract: A method of converting a digital video signal having a luminance component for each pixel of a frame and two color difference components for contiguous groups of pixels in the frame into a video signal having three color components for each pixel is disclosed. Two color lookup tables are provided, each being indexed by a combination of the luminance level for a pixel and a color difference component for the group including the pixel. Entries in each color lookup table include a component value for one color and a subcomponent contributing to a component value for another color. The method provides combining the luminance components and color difference components for each pixel represented in the compressed digital video signal to retrieve the color component values for the three color video signal. Two colors are extracted directly from the lookup tables. The third color component is generated by combining subcomponent values extracted from the tables.