Abstract: A block adaptive differential pulse code modulation (DPCM) system includes both a lossless DPCM processor responsive to blocks of pixel values for producing encoder command signals and a lossy DPCM compressor responsive to blocks of pixel values for producing encoder command signals. An encoder receives the encoder command signals from the lossless DPCM processor and lossy DPCM compressor and produces a compressed encoded bit stream. A switch responsive to a compression configuration signal and to the encoder command signals from the lossy compressor selectively passes the encoder command signals from the lossless processor or the lossy compressor to the encoder.

Abstract: A convex interpolation apparatus and method to map source color signals in a n-dimensional color space to target color signals in a m-dimensional color space includes finding a set of sample signals in the source color space whose convex hull encloses the given signal; determining the coefficients needed to express the given signal as a convex combination of the set of sample signals; and interpolating the source signal to obtain a target signal in the target color space by using the coefficients and the sample signals is the target color space that correspond to the sample signals selected in the source color space. The sample signals in both color spaces can be lattice points or non-lattice points. A method and apparatus are also provided which can not only determine if a point is enclosed by a convex hull of a set of points in a n-dimensional space, but also simultaneously derive the coefficients needed to express the given point as a convex combination of the set of points.

Abstract: A method for transforming input color values of a digital image to produce suitable output color values for use by a particular device is disclosed. In this method a plurality of color transforms are stored, each such transform responds to input color values of a digital image and produces output color values which can be used by the particular device. In the method an intermediate transform which is user desirable for transforming the input color values is formed by interpolating between the plurality of transforms.

Abstract: Each member of a set of transform representative data structures (such as look-up tables (LUTs), each representing an N TO M-dimensional transform), is stored in compressed form in a storage device included in, or which is otherwise accessible to, an image processing device or system. Each stored transform representative data structure may then, according to one embodiment of the invention, be selectively attached to image data being processed by the image processing device or system. According to a further aspect of the invention, image data, having compressed transform representative data attached thereto, may be processed utilizing methods and apparatus operative to detach, decompress and apply the transform represented by the decompressed transform representative data, to a decompressed version of the image data. The result of the aforementioned process is for image data to be transformed according to a transform specified by information previously attached to the image data.

Abstract: This invention provides a method for mapping an input color space to an output color space in such a way that the color reproduction characteristics of the saturated colors can be adjusted in a custom manner, while maintaining the desired tone reproduction on the neutral axis. This is accomplished by defining independently a tone transformation and a transformation for a plurality of highly saturated colors. A transformation is formed for the remaining color values having the specified transforms for the neutral and saturated colors as boundary values. In the preferred embodiment multi-dimensional look-up tables are used to implement the transform.

Abstract: This invention minimizes the color errors associated with performing conversion and/or correction of color digital image data using multi-dimensional look-up tables of a limited size. By distributing the errors across the color gamut it is possible to reduce the average color error as well as the maximum color errors associated with linear or conventional linear or nonlinear, e.g. cube-root or logarithmic, remapping schemes. The resulting advantage will be color images with greatly reduced artifacts.

Abstract: A block adaptive linear predictive coding method for encoding a signal having multi-dimensional correlation, such as an image signal as improved by employing multi-dimensional blocks of error signals for making the prediction. As a preferred mode, two statistical quantities are employed to select a quantizer from a set of minimum square error two-variable quantizers based on probability models of statistical quantities.

Abstract: General periodic, non-rectangular subsampling of color image data is accomplished with separable filters by convolving a periodically upsampled version of the color image with rotated one-dimensional filters and subsampling in a raster format.

Abstract: A digital halftone image is produced by providing a binary bit image pattern having a minimum visual noise for each density level in the image, and the binary bit patterns being correlated in a manner that reduces visual noise resulting from transitions between patterns. The patterns are addressed by pixel density and x,y location to produce a halftone image. The patterns are generated by employing a stochastic minimization technique with a constraint to insure correlation between patterns.

Abstract: A halftoning method for creating a color binary image from a continuous tone color image or computer generated graphics signal is improved by diffusing color vector error and by including the visual color blur functions in the recursive error propagation algorithm so that perceived color vector rather than binary color error is propagated.

Abstract: A halftoning method for creating a binary image from a continuous-tone image or computer generated graphics signal is improved by including the human visual blur function in a recursive error propagation algorithm so that perceived error rather than binary error is propagated.

Abstract: A digital halftone image is produced by providing a binary bit image pattern having a minimum visual noise for each density level in an image. The patterns are produced by employing a stochastic combinatorial minimization technique and a human visual system modulation transfer function (MTF) weighting function to generate a halftone pattern for each density level of the multi-level digital image signal. A halftone image is produced by modularly addressing these patterns with each pixel value in the image.

Abstract: A method for reducing noise in an image signal includes the steps of sampling an image to produce a sampled image signal representing pixel amplitude values, the sampled image signal including noise having a known probabilty density function (pdf); digitizing the pixel amplitude values to produce a digital image; forming an image difference signal from the digital image signal by taking the difference between successive pixel amplitude values; processing the image difference signal in digital processing means including a digital MAP filter incorporating a MAP estimator for estimating the signal and noise pdf's of a signal having a Laplacian pdf degraded by noise having a know pdf, to produce a MAP filtered image difference signal; and recovering a restored digital image signal from the MAP filtered image difference signal by summing successive amplitude difference values in the MAP filtered image difference signal.

Abstract: A block adaptive linear predictive coding method for encoding a digital image is improved by calculating the mean of the error signals in each block, and selecting a quantizer for each block, using the calculated signal and the calculated mean, from a set of minimum square error two-variable quantizers.

Abstract: A method of making a thin lens having a desired high order curvature includes the steps of providing a layer of transparent photoresist; generating a continuous tone exposure pattern for exposing the photoresist such that when exposed and developed the layer of photoresist will possess the desired high order curvature; exposing the layer of photoresist; and developing the layer to produce the thin lens.

Abstract: An image signal is segmented into regions of constant contrast or variance by applying a generalized-likelihood-ratio test to an image difference signal.

Abstract: A circuit for detecting the discharge level of a long life battery, such as a lithium battery, in which the battery is periodically subjected to an increased load for short durations of time. The periodic increases in load allows the end of battery life to be predicted and detected prior to the time the battery is fully depleted. Forecasting the end of battery life ensures that the battery will have sufficient energy to reliably operate the discharge level detection circuitry before the battery is fully depleted.