System and method for dithering with reduced memory
First Claim
1. A method to dither an image representable by lines of clockable 24-bit pixels, each of said pixels represented as red, green, and blue primary color signals using 8-bits of information, the method comprising the following steps:
- (a) for each of said 8-bit wide red, green, and blue color signals, defining an error signal based upon less than 8-bit width color representation; and
(b) for each of said red, green, and blue color signals, presetting said error signal to different values for different said lines comprising said image; and
(c) generating said image lines so that a vertical artifact in an image formed from said colors using said different preset error for said different lines will appear at a different location on at least a plurality of adjacent lines of said image.
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Abstract
A dithering system yielding two-dimensional dither functioning is implemented without line memories. For each primary input color, a feedback loop outputs an color input signal plus error that can be preset to different values. The desired result is that vertical artifacts on a display formed from the output signals are relocated to different locations on consecutive display lines. If signal magnitude from the feedback loop output exceeds the magnitude of the video system creating the display, signal magnitude is preset to a value representing error at the start of the display line.
7 Citations
22 Claims
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1. A method to dither an image representable by lines of clockable 24-bit pixels, each of said pixels represented as red, green, and blue primary color signals using 8-bits of information, the method comprising the following steps:
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(a) for each of said 8-bit wide red, green, and blue color signals, defining an error signal based upon less than 8-bit width color representation; and (b) for each of said red, green, and blue color signals, presetting said error signal to different values for different said lines comprising said image; and (c) generating said image lines so that a vertical artifact in an image formed from said colors using said different preset error for said different lines will appear at a different location on at least a plurality of adjacent lines of said image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method to dither an image representable by clockable 8-bit wide red, green, and blue color signals, the method comprising the following steps:
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(a) for each of said 8-bit wide red, green, and blue color signals generating a one-dimensional dither function having less than 8-bit color width; (b) for each 8-bit wide red, green, and blue color signals, using feedback to generate an error signal based upon bit-limiting said color signals to less than 8-bit width; (c) if magnitude of one of said 8-bit wide color signals plus said error at step (b) exceeds a threshold associated with a system displaying said image, presetting said error to magnitude of said error at the start of a line of said image; and (d) generating a plurality of adjacent lines of said image to realize a two-dimensional dither function in which any vertical artifacts in the image formed from said colors is reduced even if said magnitude at step (c) is large. - View Dependent Claims (10)
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11. A system to dither an image representable by lines of clockable 24-bit pixels, each of said pixels represented as red, green, and blue primary color signals using 8-bits of information, the system comprising:
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for each of said 8-bit wide red, green, and blue color signals, means for generating an output signal comprising one of said 8-bit wide color signals plus an error signal based upon less than 8-bit wide color representation; means for presetting magnitude of each said output signal to different values for different said lines comprising said image; and means for generating said image lines so that a vertical artifact in an image formed from said colors using said different preset error for said different lines will appear at a different location on at least a plurality of adjacent lines of said image. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A system to dither an image representable by lines of clockable 24-bit pixels, each of said pixels represented as red, green, and blue primary color signals using 8-bits of information, the system comprising:
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for each of said 8-bit wide red, green, and blue color signals, means for generating an error signal based upon less than 8-bit wide color representation; for each of said 8-bit wide red, green, and blue color signals, means for presetting said error signal to different values for different said lines comprising said image; means for presetting said error signal at a start of a line of said image to a magnitude representing error if any of said 8-bit wide color signals plus said error exceeds a threshold magnitude associated with said system; and means for generating said image lines so that a wherein vertical artifact in an image formed from said colors using said different preset error for said different lines will appear at a different location on at least a plurality of adjacent lines of said image. - View Dependent Claims (20)
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21. A method for dithering at least a portion of an image representable by lines of clockable 24-bit pixels, each of said pixels represented as red, green, and blue primary color signals using 8-bits of information, the method comprising the steps:
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(a) for each of said 8-bit wide red, green, and blue color signals, defining an error signal based upon less than 8-bit width color representation; (b) for each of said red, green, and blue color signals, presetting said error signal to different values for different said lines comprising said image; (c) generating plurality of adjacent lines so that any vertical artifacts in an image formed from said colors that occur in said plurality of adjacent lines will appear at a different location in said at least two adjacent lines of said image; (d) if magnitude of any of said 8-bit wide color signals plus said error at step (b) exceeds a threshold associated with a system displaying said image, presetting said error to magnitude of said error at the start of a line of said image so that any vertical artifact in an image formed from said colors is reduced even if said magnitude at step (b) is large; (e) for each of said colors, feeding back said error signal defined at step (a) to generate a sum of said 8-bit wide color and said error signal; (f) for each of said red, green, and blue colors, bit-limiting said sum generated at step (c); and (g) outputting as red, green, and blue color data bit-limited sums created at step (f) so that an image formed from color data output at step (e) exhibits reduced quantization error.
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22. A system to dither an image representable by lines of clockable 24-bit pixels, each of said pixels represented as red, green, and blue primary color signals using 8-bits of information, the system comprising:
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for each of said 8-bit wide red, green, and blue color signals, means for generating an error signal based upon less than 8-bit wide color representation; for each of said 8-bit wide red, green, and blue color signals, means for presetting said error signal to different values for different said lines comprising said image; at least one circuit for presetting said error signal to a magnitude representing error at a start of a line of said image if any of said 8-bit wide color signals plus said error exceeds a threshold magnitude associated with said system; and at least one circuit for generating a plurality of adjacent lines of said image using said different values of preset magnitude in said different lines so that any vertical artifacts in an image formed from said colors signals that occur in said plurality of adjacent lines will appear at a different location in said plurality of adjacent lines of said image.
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Specification