Abstract: Midtone correction of RGB pixel values is provided, without changes in chromaticity, by multiplying each color component of a linear RGB representation by a single value. The single value corresponds to an adjustment of the original luminance of the pixel, resulting in no change to the chromaticity of the pixel.

Abstract: Color crosstalk is determined between layers of an image storage medium based on the cross correlations and autocorrelations of noise in the grain pattern in each layer of the image storage medium. Rather than relying on prior measurement under laboratory conditions, the invention scans the storage medium in a plurality of spectral bands to derive the record stored in each of the dye layers. A computer derives the autocorrelations and the crosscorrelations of a group of pixels between the plurality of color records of the scanned images each of which corresponds to one of the spectral bands. The invention is based on the observation that as each dye layer is deposited separately in the film, one would expect that the "noise" from the grain boundaries in one layer to be independent from the "noise" due to the grain boundaries in other layers. If there is correlation in noise between separate color scans, it is because the scanner is measuring the grain boundaries in more than one layer in the color scans.

Abstract: The user moves a mouse to position a cursor on the original image and depresses the mouse pushbutton to designate a first corner (x1, y1) of the initially desired rectangular cropped image. The mouse is then manually moved and the sequentially updated position of the cursor instantaneously defines a second corner (x2, y2) diagonally opposite the first corner. All the time the mouse is moved and its pushbutton still depressed a sequentially varying area potential cropped image and a correspondingly sized obscured portion are displayed. If the user is satisfied with the aesthetics of the current cropped image he or she releases the mouse pushbutton, moves the cursor within the boundaries of the current cropped image and double clicks in order to select this cropped image for further processing, such as inclusion into a document being concurrently displayed in another window.

Abstract: A method and system for gamut-mapping color images from device-independent form to device-dependent gamut in a Cartesian color space. Digital images are mapped to any device-dependent gamut in a manner that minimizes the human visual response both to the luminance and the chrominance changes necessary to force out-of-gamut pixels into the specified device-dependent gamut. A "neighborhood gamut mapping" technique considers the subjective visual effects of nearby pixels on the mapping of each pixel. Image luminance is biased toward the luminance in the device-dependent gamut at which the greatest chromamagnitude is available for a fixed hue angle. The chrominance of the mapped image is thereby imperceptibly adjusted to compensate for the human visual effects of luminance changes. Spatial filtering exploits the differing spatial frequency regions of insensitive human visual response to both luminance and chrominance changes.

Abstract: The invention concerns the conversion of an input color to an output color using a multi-variable function having an input domain in a first three-dimensional color space and output range in a second m-dimensional color space. The conversion from input to output color subdivides the input domain into polyhedra defined by planar grids of points connected to form a plurality of triangles. The planar grids are projected into the remaining dimension of the function domain. When an input color value is presented, the multi-variable function is used to approximate the input value by computing an approximation of the multi-variable function, which provides a value in the output range. A tetrahedron containing the input color value is extracted from the function domain. The values of the multi-variable function at the tetrahedron vertices are obtained by interpolation. The tetrahedron is subdivided into subtetrahedra. The volumes of the subtetrahedra are calculated and multiplied by the function values.

Abstract: A method for update writing in an array of DASDs in a reduced number of DASD track cycles. The method involves distributing data and parity blocks for each parity group across the array in failure independent form and reserving unused space. During a first cycle, the old data and parity blocks are read. The new parity is calculated and shadow written into reserved unused space located before the old parity block recurs. The amended data is either written in place during a second cycle or shadow written into reserved space during a subsequent portion of the first cycle.

Abstract: Apparatus and method for calibrating a display, such as a raster display, copier, liquid crystal display (LCD) or a printer is disclosed. The processor, under the control of an algorithm, generates adjustment images with a symbol that appears light on dark when misadjusted in one direction; dark on light when misadjusted the other way; and disappears at the point when the display is adjusted correctly. The invention can be used to calibrate brightness, color, gamma and sharpness.

Abstract: An improved architecture for a computerized branch exchange particularly for a time division multiplexed bus used in the exchange. An intershelf bus includes a unidirectional source bus which receives signals from expanders and a unidirectional destination bus which transmits signals to the expanders. The expanders, through another bus, communicate with line cards which interface with telephone station sets, commercial lines, etc. A time division multiplexed controller updates distributed connection tables contained in each of the expanders and controls the flow of data onto and from the unidirectional buses. The distributed connection tables eliminate the need to broadcast addresses during each time slot. The arrangement is particularly useful in reducing blocking associated with prior art bidirectional buses.

Abstract: Undesired oscillations in a communications conferencing network are reduced and/or eliminated by frequency shifting signals passing through the conferencing network by a small amount for each pass therethrough.Electrical information signals from a plurality of individual communication sets are individually summed, frequency shifted by a predetermined amount, and coupled back to individual ones of the communication sets, less their individual signal contributions. Frequency shifting is performed on analog electrical information signals by modulating the sum signals, filtering the modulated signals and remodulating the filtered signals with a second carrier signal train having a frequency which differs from the frequency of the first carrier signal train by a predetermined amount, and filtering the signals resulting from the second modulating step.

Abstract: In a digital information transmission system having an analog-to-digital converter (ADC), an information transmission medium, and a digital-to-analog converter (DAC) all located between a transmitting station and a receiving station, signal transmission is improved by injection of a controlled signal in the form of a symmetric triangle wave sweep having a maximum peak-to-peak amplitude exceeding the magnitude of a few quantization intervals of the ADC and the DAC, introducing frequency components concentrated outside the system frequency spectrum. A class of controlled signals is disclosed. In the preferred embodiment, the controlled signal is injected into the analog information input signal prior to conversion to digital form.

Abstract: A key telephone adapter unit providing interconnection between a key telephone instrument having a line selector unit with a plurality of lines and a corresponding plurality of line status indicators and an electronic telephone switching system in which audio frequency voice information signals and supervisorial serial data signals are interfaced to individual telepone handsets by first and second conductor pairs.The adapter unit responds to a serial data polling command received from the switching system over the data pair by converting signals representative of the status of each line of the associated key telephone instrument to serial data signals for transfer to the switching system over the data pair; and responds to other serial data commands received from the switching system over the data pair by generating command signals for directing operation of the line status indicators, e.g. the status lamps, the bell and the buzzer.

Abstract: A method and apparatus for reducing idle channel noise, cross talk and quantizing error noise in a digital information transmission system designed for operation over a predetermined frequency spectrum and having an analog-to-digital converter, an information transmission medium, and a digital-to-analog converter all located between a transmitting station and a receiving station. A controlled noise signal having an amplitude lying in the range from about 1/4 to 1/2 of the magnitude of a quantizing interval of the ADC and DAC and a frequency content concentrated at (n+1/2) times the ADC and DAC sampling frequency but outside the system frequency spectrum is added to the analog information input signals prior to conversion to digital form.