Pixel data formatting
First Claim
1. A pixel mapping unit for use in a computer graphics system, the system including a color table memory and a display memory for providing a pixel data word containing a channel intensity value, the pixel data word including two or more data bits, wherein the pixel mapping unit comprises:
- A. means for determining an overlay value by selecting certain ones of the data bits of the pixel data word; and
B. means for determining a color table memory address from the overlay value.
3 Assignments
0 Petitions
Accused Products
Abstract
Pixel formats and a pixel mapping unit for use in a computer graphics terminal which provides an address input to a color look-up table. The disclosed pixel formats can be used to conserve frame buffer memory, color table memory, or both. For example, the formats support pseudo color or full color mapping, overlay planes, and color table bank select while using a minimum amount of memory. A valid plane feature is also supported, which can be used to enable rapid clearing of a window. The pixel mapping unit is especially handy in supporting multiple windows, because a unique mapping configuration word, which specifies how pixels are to be interpreted, may be specified for each window.
39 Citations
20 Claims
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1. A pixel mapping unit for use in a computer graphics system, the system including a color table memory and a display memory for providing a pixel data word containing a channel intensity value, the pixel data word including two or more data bits, wherein the pixel mapping unit comprises:
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A. means for determining an overlay value by selecting certain ones of the data bits of the pixel data word; and B. means for determining a color table memory address from the overlay value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 20)
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10. A pixel mapping unit for use in a color computer graphics system, the system including a plurality of color channel intensity inputs, a color table memory, and a frame buffer memory which provides pixel data words each containing at least one channel intensity value, and the system performing a pseudocolor mapping operation wherein the same intensity value is provided to each of the channel intensity inputs, and the system performing a full color mapping operation wherein different intensity values are provided to each of the color channel intensity inputs, the pixel mapping unit comprising:
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A. means for providing a mapping configuration word associated with each pixel data word; and B. means for a selecting one of the pseudocolor or full color pixel mapping operation to be carried out on a particular pixel data word in accordance with the value of the mapping configuration word associated with the pixel data word. - View Dependent Claims (11)
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12. A pixel mapping unit for use in a computer graphics system, the system including a color table memory, and the system providing pixel data words each containing at least one channel intensity value, the pixel mapping unit comprising:
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A. means for providing a mapping configuration word associated with each pixel data word, B. each mapping configuration word having a bitonal mode enable field, a background offset field, and a foreground offset field, the bitonal mode enable field indicating whether a bitonal mode is enabled in which a single selected bit of each pixel data word specifies the output intensity value, the background offset field indicating a background offset address, and the foreground offset field indicating a foreground offset address; B. a means for selecting an offset address from one of the background offset field and the foreground offset field if the bitonal mode enable field indicates that the bitonal mode is enabled; C. means for providing a base address; and D. means for adding the base address to the selected offset if the bitonal mode is enabled, to provide a color table memory address.
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13. A pixel mapping unit for use in a computer graphics system, the system including a color table memory and a frame buffer memory which provides pixel data words each containing at least one channel intensity value, the pixel mapping unit comprising:
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A. means for providing a mapping configuration word associated with each pixel data word, each mapping configuration word having a valid plane field indicating whether a valid plane mode is enabled in which one of the bits of each pixel data word indicates whether the other bits in that pixel data word are valid or not; B. means for providing a window number word associated with each pixel data word, the window number word depending upon the frame buffer memory address from which the pixel data value was provided; C. means for providing a color table address dependent upon the value of the window number word; and D. means for selecting the color table address in place of the pixel data values when the valid plane field indicates that the valid plane mode is enabled.
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14. A pixel mapping unit for use in a graphics system which supports displaying a multiple number of windows, the system including a frame buffer memory which provides pixel data words, wherein one bit of each pixel data word is a valid plane bit, the valid plane bit indicating whether the other bits in the pixel data word contain valid pixel data, the pixel mapping unit comprising:
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A. means for storing a list of background color table addresses, wherein one background color table address is stored for each window; B. means for monitoring the value of the valid plane bit as the pixel data words are read from the frame buffer memory; C. means for providing a window number associated with each pixel data word, the window number depending upon the frame buffer memory address from which the pixel data value was read; and D. means, connected to receive the window number, the background color table addresses, and the valid plane bit, for outputting the background color table address associated with the window number when the valid plane bit is logically true.
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15. A pixel mapping unit for operating on an input pixel data word and a window number word, the input pixel data word provided by a frame buffer memory, and the window number word having a value depending upon the frame buffer address associated with the pixel data word, the pixel mapping unit providing a mapped intensity data output, the mapped intensity data output indicating an address input to a color look-up table memory, the pixel mapping unit comprising:
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A. a mapping memory, connected to receive the window number at address inputs, and to provide a mapping configuration word at data outputs, the mapping configuration word containing a mode field, base address field, number of planes field, shift field, and mask field, the mode field indicating an operating instruction for the pixel mapping unit, the base address field indicating a base color table address to which the results of the operations of the pixel mapping unit are to be added, the number planes field indicating the total number of active bits in the pixel data word, the shift field indicating the number of bit positions to shift the pixel data word, and the mask field indicating which of the bits in the pixel data word are to be used as an overlay value; B. a barrel shifter, connected to receive the pixel data and the shift field, and to provide shifted pixel data shifted by the number of bits indicated by the shift field; C. a mask unit, connected to receive the shifted pixel data and the number of planes field, and to provide masked pixel data; D. an overlay selector, connected to receive the pixel data, the mode field, and the mask field, and to provide an overlay value, and an overlay value complement, the overlay value taken from one or more predetermined bits of the pixel data depending upon the mode field and the mask field; E. a multiplexer, connected to receive the mode field, and to select one of the overlay value complement and the masked pixel data as a multiplexer output, depending on the overlay value; and F. an adder, connected to add the multiplexer output and the base address field, and to provide the mapped intensity data output.
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16. A pixel mapping unit for operating on a pixel data word and a window number, the input pixel data word provided by a frame buffer memory, and the window number having a value depending upon the frame buffer address associated with the pixel data word, the pixel mapping unit for providing an address to a color look-up table memory, the pixel mapping unit comprising:
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A. means for selecting a variable number of bits of the pixel data word as active pixel plane bits, the number of bits so selected depending upon the window number, the active pixel plane bits including a most significant active pixel plane bit, and the active pixel plane bits occurring in any contiguous order in the pixel data word; and B. means for selecting a plurality of the bits of the pixel data word as overlay plane bits, the overlay plane bits positioned in the immediate next highest bit positions adjacent the most significant pixel plane bit, regardless of the number of active pixel plane bits; and C. means for determining the color table memory address from the overlay plane bits. - View Dependent Claims (17)
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18. A pixel mapping unit for operating on a pixel data word and a window number, the input pixel data word provided by a frame buffer memory, and the window number having a value depending upon the frame buffer address associated with the pixel data word, the pixel mapping unit providing an address to a color look-up table memory, the pixel mapping unit comprising:
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A. means for selecting a variable number of active pixel plane bits from the pixel data word, the active pixel plane bits including red, green, and blue color channel intensity values, each channel intensity value having a least significant bit position, and the active pixel plane bits occurring in any contiguous order in the pixel data word; and B. means for selecting an overlay plane bit occupying the least significant bit position of one of the color channel intensity values; and C. means for determining the color table memory address from the overlay plane bits. - View Dependent Claims (19)
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Specification