Method and apparatus for dithering graphic images

Claim 1

A system for dithering an image comprising a plurality of pixels and displaying said image on a graphics display monitor, said system comprising: an input device for inputting image information to said system; an input/output circuit coupled to said input device for formatting said image information; a graphics display monitor for displaying said image on a two-dimensional display screen, said display monitor coupled to said input/output circuit; a memory circuit coupled to said input/output circuit; means for generating a first plurality of electrical signals wherein each one of said first plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates an input intensity for that separate one of said plurality of pixels; means for generating a second plurality of electrical signals wherein each one of said second plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates an output quantized intensity value for that separate one of said plurality of pixels; means for generating a third plurality of electrical signals wherein each one of said third plurality of electrical signals corresponds to a dither matrix entry and further indicates a dither matrix value; means for comparing said first plurality of electrical signals to said second plurality of electrical signals and utilizing the results of said comparisons to generate a fourth plurality of electrical signals, wherein each one of said fourth plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates the intensity difference between the output quantized intensity value and the input intensity value for that separate one of said plurality of pixels; means for modifying said fourth plurality of electrical signals based upon the range of dither matrix values in said third plurality of electrical signals to generate a fifth plurality of electrical signals; means for comparing said third plurality of electrical signals to said fifth plurality of electrical signals, and utilizing the results of said comparisons to generate a sixth plurality of electrical signals, wherein each one of said sixth plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates a dithered output intensity for that separate one of said plurality of pixels; means for applying said sixth plurality of electrical signals to said graphics display monitor; means for actuating said plurality of pixels at specified locations and intensities on said graphics display monitor in accordance with the dithered output intensities indicated by said sixth plurality of electrical signals.

Claim 2

A system for dithering an image comprising a plurality of pixels and displaying said image on a graphics display monitor, said system comprising: an input device for inputting image information to said system; an input/output circuit coupled to said input device for formatting said image information; a graphics display monitor for displaying said image on a two-dimensional display screen, said display monitor coupled to said input/output circuit; a memory circuit coupled to said input/output circuit; means for generating a first plurality of electrical signals wherein each one of said first plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates an input intensity for that separate one of said plurality of pixels; means for generating a second plurality of electrical signals wherein each one of said second plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates an output quantized intensity value for that separate one of said plurality of pixels; means for generating a third plurality of electrical signals wherein each one of said third plurality of electrical signals corresponds to a dither matrix entry and further indicates a dither matrix value; means for comparing said first plurality of electrical signals to said second plurality of electrical signals and utilizing the results of said comparisons to generate a fourth plurality of electrical signals, wherein each one of said fourth plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates the intensity difference between the output quantized intensity value and the input intensity value for that separate one of said plurality of pixels; means for modifying said fourth plurality of electrical signals based upon the range of dither matrix values in said third plurality of electrical signals to generate a fifth plurality of electrical signals; means for comparing said third plurality of electrical signals to said fifth plurality of electrical signals, and utilizing the results of said comparisons to generate a sixth plurality of electrical signals, wherein each one of said sixth plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates a dithered output intensity for that separate one of said plurality of pixels; means for applying said sixth plurality of electrical signals to said graphics display monitor; means for actuating said plurality of pixels at specified locations and intensities on said graphics display monitor in accordance with the dithered output intensities indicated by said sixth plurality of electrical signals.

Claim 3

An apparatus for dithering a digital image from an input intensity range to an output intensity range of quantized intensity values and displaying said dithered digital image, said digital image comprising a plurality of pixels, each pixel having an input intensity value associated with it from the input intensity range, wherein said digital image is dithered from a q-bit intensity value per color component per pixel, to a p-bit intensity value per color component per pixel, where p is a value less than q, the number of elements in the input intensity range being 2q and the number of elements in the output intensity range being 2P, said apparatus comprising; a graphics display monitor comprising a matrix of pixels; a frame buffer; means for generating a first mapping function between said input range of intensity values and said output range of quantized intensity values; means for determining a base value for the input intensity value of each of said plurality of pixels, said base value being an input scale value corresponding to a quantized intensity value which is closest to, but not greater than the input intensity value; means for determining an interval between quantized intensity values the input intensity value is within, said interval comprising the values from, and including, the intensity value corresponding to the base value, up to the intensity value corresponding to the base value +1; means for determining a distance value, said distance value being the distance between the input intensity value of a pixel and the quantized intensity value which corresponds to the base value; a dither matrix comprising a range of dither values; means for retrieving a dither value from said dither matrix; means for generating a second mapping function between the range of dither values in said dither matrix and the range of values in said interval; means for adjusting the distance value according to the second mapping function; a comparator for comparing said adjusted distance value and said retrieved dither value; means for setting the output intensity value based on the comparison of said adjusted distance value and said retrieved dither value, said means setting the output intensity value to be equal to the quantized intensity value corresponding to the base value, in the event said adjusted value is less than, or equal to, said retrieved dither value; and said means setting the output intensity value to be equal to the quantized intensity value corresponding to the base value +1in the event said adjusted value is greater than said retrieved dither value; output means for storing in the frame buffer the output intensity value for each pixel in said plurality of pixels at a location corresponding to that pixel; frame buffer control means for retrieving said plurality of pixels stored in the frame buffer and generating a plurality of electrical signals to actuate said plurality of pixels on said graphics display monitor such that each pixel is actuated at an intensity indicated by the stored output intensity level for that pixel; whereby said plurality of pixels comprising said digital image are dithered and actuated on said graphics display monitor.

Claim 4

An apparatus for dithering a digital image from an input intensity range to an output intensity range of quantized intensity values and displaying said dithered digital image, said digital image comprising a plurality of pixels, each pixel having an input intensity value associated with it from the input intensity range, wherein said digital image is dithered from a q-bit intensity value per color component per pixel, to a p-bit intensity value per color component per pixel, where p is a value less than q, the number of elements in the input intensity range being 2q and the number of elements in the output intensity range being 2P, said apparatus comprising; a graphics display monitor comprising a matrix of pixels; a frame buffer; means for generating a first mapping function between said input range of intensity values and said output range of quantized intensity values; means for determining a base value for the input intensity value of each of said plurality of pixels, said base value being an input scale value corresponding to a quantized intensity value which is closest to, but not greater than the input intensity value; means for determining an interval between quantized intensity values the input intensity value is within, said interval comprising the values from, and including, the intensity value corresponding to the base value, up to the intensity value corresponding to the base value +1; means for determining a distance value, said distance value being the distance between the input intensity value of a pixel and the quantized intensity value which corresponds to the base value; a dither matrix comprising a range of dither values; means for retrieving a dither value from said dither matrix; means for generating a second mapping function between the range of dither values in said dither matrix and the range of values in said interval; means for adjusting the distance value according to the second mapping function; a comparator for comparing said adjusted distance value and said retrieved dither value; means for setting the output intensity value based on the comparison of said adjusted distance value and said retrieved dither value, said means setting the output intensity value to be equal to the quantized intensity value corresponding to the base value, in the event said adjusted value is less than, or equal to, said retrieved dither value; and said means setting the output intensity value to be equal to the quantized intensity value corresponding to the base value +1in the event said adjusted value is greater than said retrieved dither value; output means for storing in the frame buffer the output intensity value for each pixel in said plurality of pixels at a location corresponding to that pixel; frame buffer control means for retrieving said plurality of pixels stored in the frame buffer and generating a plurality of electrical signals to actuate said plurality of pixels on said graphics display monitor such that each pixel is actuated at an intensity indicated by the stored output intensity level for that pixel; whereby said plurality of pixels comprising said digital image are dithered and actuated on said graphics display monitor.

Claim 7

An apparatus for dithering a digital image from an input intensity range to an output intensity range of quantized intensity values and displaying said dithered digital image, said digital image comprising a plurality of pixels, each pixel having an input intensity value associated with it from the input intensity range, wherein said digital image is dithered from a q-bit intensity value per color component per pixel, to a p-bit intensity value per color component per pixel, where p is a value less than q, the number of elements in the input intensity range being 2q and the number of elements in the output intensity range being 2P, said apparatus comprising: a graphics display monitor comprising a matrix of pixels; a frame buffer; means for generating a first mapping function between said input range of intensity values and said output range of quantized intensity values; means for determining a base value for the input intensity value of a pixel, said base value being an input scale value corresponding to a quantized intensity value which is closest to, but not less than the input intensity value; means for determining an interval between quantized intensity values the input intensity value is within, said interval comprising the values from, and including, the intensity value corresponding to the base value, down to the intensity value corresponding to the base value -1; means for determining a distance value, said distance value being the distance between the input intensity value of the pixel and the quantized intensity value which corresponds to the base value; a dither matrix comprising a range of dither values; means for retrieving a dither value from said dither matrix; means for generating a second mapping function between the range of dither values in said dither matrix and the range of values in said interval; means for adjusting the distance value according to the second mapping function; a comparator for comparing said adjusted distance value and said retrieved dither value; means for setting the output intensity value based upon the comparison of said adjusted distance value and said retrieved dither value, said means setting the output intensity value to be equal to the quantized intensity value corresponding to the base value, in the event said adjusted value is greater than, or equal to, said retrieved dither value, and said means for setting the output intensity value to be equal to the quantized intensity value corresponding to the base value -1, in the event said adjusted value is less than said retrieved dither value; output means for storing in the frame buffer the output intensity value for each pixel in said plurality of pixels at a location corresponding to that pixel; frame buffer control means for retrieving said plurality of pixels stored in the frame buffer and generating a plurality of electrical signals to actuate said plurality of pixels on said graphics display monitor such that each pixel is actuated at an intensity indicated by the stored output intensity level for that pixel; whereby said plurality of pixels comprising said digital image are dithered and actuated on said graphics display monitor.

Claim 8

An apparatus for dithering a digital image from an input intensity range to an output intensity range of quantized intensity values and displaying said dithered digital image, said digital image comprising a plurality of pixels, each pixel having an input intensity value associated with it from the input intensity range, wherein said digital image is dithered from a q-bit intensity value per color component per pixel, to a p-bit intensity value per color component per pixel, where p is a value less than q, the number of elements in the input intensity range being 2q and the number of elements in the output intensity range being 2P, said apparatus comprising: a graphics display monitor comprising a matrix of pixels; a frame buffer; means for generating a first mapping function between said input range of intensity values and said output range of quantized intensity values; means for determining a base value for the input intensity value of a pixel, said base value being an input scale value corresponding to a quantized intensity value which is closest to, but not less than the input intensity value; means for determining an interval between quantized intensity values the input intensity value is within, said interval comprising the values from, and including, the intensity value corresponding to the base value, down to the intensity value corresponding to the base value -1; means for determining a distance value, said distance value being the distance between the input intensity value of the pixel and the quantized intensity value which corresponds to the base value; a dither matrix comprising a range of dither values; means for retrieving a dither value from said dither matrix; means for generating a second mapping function between the range of dither values in said dither matrix and the range of values in said interval; means for adjusting the distance value according to the second mapping function; a comparator for comparing said adjusted distance value and said retrieved dither value; means for setting the output intensity value based upon the comparison of said adjusted distance value and said retrieved dither value, said means setting the output intensity value to be equal to the quantized intensity value corresponding to the base value, in the event said adjusted value is greater than, or equal to, said retrieved dither value, and said means for setting the output intensity value to be equal to the quantized intensity value corresponding to the base value -1, in the event said adjusted value is less than said retrieved dither value; output means for storing in the frame buffer the output intensity value for each pixel in said plurality of pixels at a location corresponding to that pixel; frame buffer control means for retrieving said plurality of pixels stored in the frame buffer and generating a plurality of electrical signals to actuate said plurality of pixels on said graphics display monitor such that each pixel is actuated at an intensity indicated by the stored output intensity level for that pixel; whereby said plurality of pixels comprising said digital image are dithered and actuated on said graphics display monitor.

Claim 9

A method for dithering and displaying an image on a graphics display monitor, said image comprising a plurality of pixels, said method comprising the steps of: generating a first plurality of electrical signals wherein each one of said first plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates an input intensity for that separate one of said plurality of pixels; generating a second plurality of electrical signals wherein each one of said second plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates an output quantized intensity value for that separate one of said plurality of pixels; generating a third plurality of electrical signals wherein each one of said third plurality of electrical signals corresponds to a dither matrix entry and further indicates a dither matrix value; comparing said first plurality of electrical signals to said second plurality of electrical signals and utilizing the results of said comparisons to generate a fourth plurality of electrical signals, wherein each one of said fourth plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates the intensity difference between the output quantized intensity value and the input intensity value for that separate one of said plurality of pixels; modifying said fourth plurality of electrical signals based upon the range of dither matrix values in said third plurality of electrical signals to generate a fifth plurality of electrical signals; comparing said third plurality of electrical signals to said fifth plurality of electrical signals, and utilizing the results of said comparisons to generate a sixth plurality of electrical signals, wherein each one of said sixth plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates a dithered output intensity for that separate one of said plurality of pixels; applying said sixth plurality of electrical signals to said graphics display monitor; actuating said plurality of pixels at specified locations and intensities on said graphics display monitor in accordance with the dithered output intensities indicated by said sixth plurality of electrical signals.

Claim 10

A method for dithering and displaying an image on a graphics display monitor, said image comprising a plurality of pixels, said method comprising the steps of: generating a first plurality of electrical signals wherein each one of said first plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates an input intensity for that separate one of said plurality of pixels; generating a second plurality of electrical signals wherein each one of said second plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates an output quantized intensity value for that separate one of said plurality of pixels; generating a third plurality of electrical signals wherein each one of said third plurality of electrical signals corresponds to a dither matrix entry and further indicates a dither matrix value; comparing said first plurality of electrical signals to said second plurality of electrical signals and utilizing the results of said comparisons to generate a fourth plurality of electrical signals, wherein each one of said fourth plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates the intensity difference between the output quantized intensity value and the input intensity value for that separate one of said plurality of pixels; modifying said fourth plurality of electrical signals based upon the range of dither matrix values in said third plurality of electrical signals to generate a fifth plurality of electrical signals; comparing said third plurality of electrical signals to said fifth plurality of electrical signals, and utilizing the results of said comparisons to generate a sixth plurality of electrical signals, wherein each one of said sixth plurality of electrical signals corresponds to a separate one of said plurality of pixels and further indicates a dithered output intensity for that separate one of said plurality of pixels; applying said sixth plurality of electrical signals to said graphics display monitor; actuating said plurality of pixels at specified locations and intensities on said graphics display monitor in accordance with the dithered output intensities indicated by said sixth plurality of electrical signals.

Claim 11

A method for dithering a digital image from an input intensity range to an output intensity range of quantized intensity values and displaying said dithered digital image, said digital image comprising a plurality of pixels, each pixel having an input intensity value associated with it from the input intensity range, wherein said digital image is dithered from a q-bit intensity value per color component per pixel to a p-bit intensity value per color component per pixel, where p is a value less than q, the number of elements in the input intensity range being 2q, and the number of elements in the output intensity range being 2P, said method comprising the steps of: generating a first mapping function between said input range of intensity values and said output range of quantized intensity values; determining a base value for the input intensity value of each of said plurality of pixels, said base value being an input scale value corresponding to the quantized intensity value which is closest to, but not greater than the input intensity value of the pixel; determining the interval between quantized intensity values the input intensity value is within, said interval comprising the values from, and including, the intensity value corresponding to the base value up to the intensity value corresponding to the base value +1; determining a distance value, said distance value being the distance between the input intensity value of the pixel and the quantized intensity value which corresponds to the base value; providing a dither matrix having a range of dither values; retrieving a dither value from the dither matrix; generating a second mapping function between the range of dither values in the dither matrix and the range of values in the interval; adjusting the distance value according to the second mapping function; comparing with a comparator the adjusted distance value and dither value; if the adjusted distance value is less than, or equal to, the retrieved dither value, setting the output intensity value to be equal to the quantized intensity value corresponding to the base value; if the adjusted distance value is greater than the retrieved dither value, setting the output intensity value to be equal to the quantized intensity value corresponding to the base value +1; storing in a frame buffer the output intensity level for each pixel in said plurality of pixels at a location corresponding to that pixel: retrieving said plurality of pixels stored in said frame buffer; and generating a plurality of electrical signals to actuate said plurality of pixels on a graphics display monitor such that each pixel is actuated at an intensity indicated by the stored output intensity level for that pixel; whereby said plurality of pixels comprising said digital image are dithered and actuated on said graphics display monitor.

Claim 12

A method for dithering a digital image from an input intensity range to an output intensity range of quantized intensity values and displaying said dithered digital image, said digital image comprising a plurality of pixels, each pixel having an input intensity value associated with it from the input intensity range, wherein said digital image is dithered from a q-bit intensity value per color component per pixel to a p-bit intensity value per color component per pixel, where p is a value less than q, the number of elements in the input intensity range being 2q, and the number of elements in the output intensity range being 2P, said method comprising the steps of: generating a first mapping function between said input range of intensity values and said output range of quantized intensity values; determining a base value for the input intensity value of each of said plurality of pixels, said base value being an input scale value corresponding to the quantized intensity value which is closest to, but not greater than the input intensity value of the pixel; determining the interval between quantized intensity values the input intensity value is within, said interval comprising the values from, and including, the intensity value corresponding to the base value up to the intensity value corresponding to the base value +1; determining a distance value, said distance value being the distance between the input intensity value of the pixel and the quantized intensity value which corresponds to the base value; providing a dither matrix having a range of dither values; retrieving a dither value from the dither matrix; generating a second mapping function between the range of dither values in the dither matrix and the range of values in the interval; adjusting the distance value according to the second mapping function; comparing with a comparator the adjusted distance value and dither value; if the adjusted distance value is less than, or equal to, the retrieved dither value, setting the output intensity value to be equal to the quantized intensity value corresponding to the base value; if the adjusted distance value is greater than the retrieved dither value, setting the output intensity value to be equal to the quantized intensity value corresponding to the base value +1; storing in a frame buffer the output intensity level for each pixel in said plurality of pixels at a location corresponding to that pixel: retrieving said plurality of pixels stored in said frame buffer; and generating a plurality of electrical signals to actuate said plurality of pixels on a graphics display monitor such that each pixel is actuated at an intensity indicated by the stored output intensity level for that pixel; whereby said plurality of pixels comprising said digital image are dithered and actuated on said graphics display monitor.

Claim 19

A method for dithering a digital image from an input intensity range to an output intensity range of quantized intensity values and displaying said dithered digital image, said digital image comprising a plurality of pixels, each pixel having an input intensity value associated with it from the input intensity range, wherein said digital image is dithered from a q-bit intensity value per color component per pixel to a p-bit intensity value per color component per pixel, where p is a value less than q, the number of elements in the input intensity range being 2q, and the number of elements in the output intensity range being 2P, said method comprising the steps of: generating a first mapping function between said input range of intensity values and said output range of quantized intensity values; determining a base value for the input intensity value of each of said plurality of pixels, said base value being an input scale value corresponding to the quantized intensity value which is closest to, but not less than the input intensity value of the pixel; determining the interval between quantized intensity values the input intensity value is within, said interval comprising the values from, and including, the intensity value corresponding to the base value down to the intensity value corresponding to the base value -1; determining a distance value, said distance value being the distance between the input intensity value of the pixel and the quantized intensity value which corresponds to the base value; providing a dither matrix having a range of dither values; retrieving a dither value from the dither matrix; generating a second mapping function between the range of dither values in the dither matrix and the range of values in the interval; adjusting the distance value according to the second mapping function; comparing with a comparator the adjusted distance value and dither value; if the adjusted distance value is greater than, or equal to, the retrieved dither value, setting the output intensity value to be equal to the quantized intensity value corresponding to the base value; if the adjusted distance value is less than the retrieved dither value, setting the output intensity value to be equal to the quantized intensity value corresponding to the base value -1; storing in a frame buffer the output intensity level for each pixel in said plurality of pixels at a location corresponding to that pixel; retrieving said plurality of pixels stored in the frame buffer; and generating a plurality of electrical signals to actuate said plurality of pixels on a graphics display monitor such that each pixel is actuated at an intensity indicated by the stored output intensity level for that pixel; whereby said plurality of pixels comprising said digital image are dithered and actuated on said graphics display monitor.

Claim 20

A method for dithering a digital image from an input intensity range to an output intensity range of quantized intensity values and displaying said dithered digital image, said digital image comprising a plurality of pixels, each pixel having an input intensity value associated with it from the input intensity range, wherein said digital image is dithered from a q-bit intensity value per color component per pixel to a p-bit intensity value per color component per pixel, where p is a value less than q, the number of elements in the input intensity range being 2q, and the number of elements in the output intensity range being 2P, said method comprising the steps of: generating a first mapping function between said input range of intensity values and said output range of quantized intensity values; determining a base value for the input intensity value of each of said plurality of pixels, said base value being an input scale value corresponding to the quantized intensity value which is closest to, but not less than the input intensity value of the pixel; determining the interval between quantized intensity values the input intensity value is within, said interval comprising the values from, and including, the intensity value corresponding to the base value down to the intensity value corresponding to the base value -1; determining a distance value, said distance value being the distance between the input intensity value of the pixel and the quantized intensity value which corresponds to the base value; providing a dither matrix having a range of dither values; retrieving a dither value from the dither matrix; generating a second mapping function between the range of dither values in the dither matrix and the range of values in the interval; adjusting the distance value according to the second mapping function; comparing with a comparator the adjusted distance value and dither value; if the adjusted distance value is greater than, or equal to, the retrieved dither value, setting the output intensity value to be equal to the quantized intensity value corresponding to the base value; if the adjusted distance value is less than the retrieved dither value, setting the output intensity value to be equal to the quantized intensity value corresponding to the base value -1; storing in a frame buffer the output intensity level for each pixel in said plurality of pixels at a location corresponding to that pixel; retrieving said plurality of pixels stored in the frame buffer; and generating a plurality of electrical signals to actuate said plurality of pixels on a graphics display monitor such that each pixel is actuated at an intensity indicated by the stored output intensity level for that pixel; whereby said plurality of pixels comprising said digital image are dithered and actuated on said graphics display monitor.