Apple Inc.

Silicon Graphics, Incorporated

Anthony D Masterson

Steven G Roskowski

Elizabeth A Clough

Stephen G Perlman

Robert A Williams

William Dawson

James A Lundblad

Mark Krueger

Spencer Worley

Charles Jerian

Mohammed Sriti

Edward Goldberg

A system and method for converting a color represented in a first color space to the color represented in a second color space uses a constant hue algorithm. The constant hue algorithm is used to compensate invalid colors in the second color space obtained as a result of the conversion. The constant hue algorithm determines a compensation factor that, in effect, blends the invalid color with pure grey until the invalid color becomes a valid color in the second color space. The compensation factor is optionally stored with the valid color in the second color space so that the original color in the first color space can be subsequently recovered.

System and method for color space conversion

Apparatus for converting representations of color pixels in a twenty-four bit color format to representations in a fifteen bit color format including an individual circuit for data representing each component of a color, each of the individual circuits including apparatus for selectively incrementing the value the five highest order bits of a value representing a component of a color, apparatus responsive to a value of the lowest order bits of a value representing a component for providing a signal to cause the apparatus for selectively incrementing the five highest order bits, and apparatus for selectively enabling the apparatus responsive to a value of the lowest order bits depending on a desired pattern of pixels.

Apparatus for converting twenty-four bit color to fifteen bit color in a

A computer subsystem for presenting both video and graphic information on a computer output display in a computer system having a central processing unit and a frame buffer including apparatus for providing a video input signal representing full frame of video interlaced data, apparatus for selecting a rectangular portion of the video data to be presented, apparatus for converting the selected portion of the video signal into a stream of digitized pixel signals, apparatus for designating each such pixel of video information which is to be written to the frame buffer, and apparatus for addressing each of such pixels for storage at selected points of the frame buffer.

Apparatus for storing data both video and graphics signals in a single

An arrangement for storing information to be displayed in a plurality of different pixel formats on a bitmapped output display including apparatus for selecting first positions for storage of information in a first pixel format, apparatus for selecting second positions for storage of information in a second pixel format, apparatus for selecting information from first positions of storage for display in the first pixel format, and apparatus for selecting information from second positions of storage for display in the second pixel format.

Apparatus for storing information in and deriving information from a

An apparatus and method for taking data that is presented on a NUBUS in NUBUS format and writing it into a video memory in chunky planar format, is described. The present invention is also useful for performing RGB reads wherein video data is read from the video memory in chunky planar format and is translated into NUBUS format for transmission across the NUBUS. The apparatus comprises a data format translator which is coupled to the NUBUS for translating the RGB data from NUBUS format to chunky planar format. The translated RGB data in chunky planar format is compressed and rearranged as compared to the NUBUS format--resulting in a more efficient utilization of video memory space. An address generator is also coupled to the video memory for calculating the address location in the video memory where the translated RGB data is to be written. The address location is derived from the NUBUS address according to the formula N.sub.start =(3*NAD/4) where N.sub.start is the start address in video memory and NAD represents the NUBUS address from which the RGB data to be translated is obtained.

Chunky planar data packing apparatus and method for a video memory

An arrangement which includes apparatus for signifying the source of data to be displayed, apparatus for generating lines of data to fit between the lines of interlaced data to be presented on a non-interlaced output display device, and apparatus for generating lines of data to be presented on an interlaced display from a larger number of lines representing non-interlaced data.

Apparatus for providing output filtering from a frame buffer storing

A cache management system for a computer system having a central processing unit, a main memory, and cache memory including a memory management unit for transferring page size blocks of information, apparatus for reading information from main memory, apparatus for writing information to the cache memory, and apparatus for overlapping the write of information to the cache memory to occur during the read of information from the main memory.

Apparatus and method for improved caching in a computer system

A circuit for providing control signals of selectable lengths capable of being driven off of either the rising or falling edge of a clock pulse, the circuit comprising apparatus for providing signals indicating a mode of operation for access to a matrix of memory elements, apparatus responsive to the signals provided by the apparatus for providing signals indicating a mode of operation for providing signals indicating a clock period during which a control signal is to commence and the edge of the clock signal at which such signal is to commence, and apparatus responsive to the signals provided by the apparatus for providing signals indicating a mode of operation for providing signals indicating a clock period during which a control signal is to terminate and the edge of the clock signal at which such signal is to terminate.

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Cupertino, CA, United States of America

Anthony D Masterson