Dithering circuit and method
First Claim
1. A system for improving the display capability of a display device, comprisingmeans for generating the X, Y coordinates of each pixel in each frame of said display,means for storing a dither matrix and for accessing a dither matrix element D(X,Y) in response to the X,Y coordinates of each pixel,means for generating a frame count number F for each frame in a time period comprising a predetermined number of frames,means for generating an input intensity value G(X,Y) corresponding to each pixel with coordinates X,Y in each frame of said display device,means for multiplying said frame count number F and said input intensity value G(X,Y),circuit means operative during a frame in said time period for determining an output pixel intensity value I(X,Y) representing the illumination of a pixel with the coordinates X,Y in the display device during each frame in response to said dither matrix element D(X,Y), said frame count number F, said input intensity value G(X,Y), and a product (F * G(X,Y)) from said means for multiplying,means for adding said product (F * G(X,Y)) and said input intensity value G(X,Y),first means for comparing said product (F * G(X,Y)) with said dither matrix element D(X,Y),second means for comparing said dither element D(X,Y) with said addition ((F * G(X,Y))+G(X,Y)),third means for comparing said product (F * G(X,Y)) with said addition ((F * G(X,Y))+G(X,Y)),and said circuit generating an output pixel intensity in response to results from said three means for comparing.
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Abstract
A display device with improved color and grey scale capability employs an improved time dependent dithering technique. In the display device, each pixel is controlled so as to be illuminated only a certain number of times during a fixed display time period, the number of illuminations during the time period being dependent on the color or grey scale value of a corresponding pixel in an original image, the frame number, and a dither matrix element. Additionally, the device chooses the particular frames during which a pixel is illuminated so as to give a soft and smooth displayed image with no flashing.
32 Citations
11 Claims
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1. A system for improving the display capability of a display device, comprising
means for generating the X, Y coordinates of each pixel in each frame of said display, means for storing a dither matrix and for accessing a dither matrix element D(X,Y) in response to the X,Y coordinates of each pixel, means for generating a frame count number F for each frame in a time period comprising a predetermined number of frames, means for generating an input intensity value G(X,Y) corresponding to each pixel with coordinates X,Y in each frame of said display device, means for multiplying said frame count number F and said input intensity value G(X,Y), circuit means operative during a frame in said time period for determining an output pixel intensity value I(X,Y) representing the illumination of a pixel with the coordinates X,Y in the display device during each frame in response to said dither matrix element D(X,Y), said frame count number F, said input intensity value G(X,Y), and a product (F * G(X,Y)) from said means for multiplying, means for adding said product (F * G(X,Y)) and said input intensity value G(X,Y), first means for comparing said product (F * G(X,Y)) with said dither matrix element D(X,Y), second means for comparing said dither element D(X,Y) with said addition ((F * G(X,Y))+G(X,Y)), third means for comparing said product (F * G(X,Y)) with said addition ((F * G(X,Y))+G(X,Y)), and said circuit generating an output pixel intensity in response to results from said three means for comparing.
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9. A method for improving the display capability of a display device comprising
generating coordinates X,Y of each pixel in each frame of said display device, accessing a memory storing a dither matrix in response to said X,Y coordinates of each pixel in each frame to retrieve a dither matrix element D(X,Y), generating a frame count number F of each frame in a display time period comprising a predetermined number of frames of said display device, inputting into a processing unit for each pixel in each frame in the display time period, an input intensity G(X,Y) of a pixel with coordinates X,Y, a dither matrix value D(X,Y), and a frame count number F, multiplying said input intensity G(X,Y) by said frame count number F, outputting from said processing unit an output intensity I(X,Y) for each pixel with coordinates of each frame of said display device in response to said dither matrix element D(X,Y), said frame count number F, said input intensity value G(X,Y), and a product (F * G(X,Y)) from said means for multiplying, adding said product (F * G(X,Y)) to said input intensity value G (X,Y), comparing said product (F * G(X,Y)) with said dither matrix element D(X,Y), comparing said dither matrix element D(X,Y) to said addition ((F * G(X,Y))+G(X,Y), comparing said product (F * G(X,Y)) to said addition ((F * G(X,Y))+G(X,Y)), and generating an output pixel intensity in response to said three comparisons.
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10. A binary display device capable of displaying a multiple intensity scale image comprising
a circuit which represents an input pixel having a specific multiple intensity scale value by illuminating a corresponding pixel on said binary display for a specific number of frames in a display period, the specific number of illuminated frames being proportionate to the specific multiple intensity scale value, said number of illuminated frames being spread evenly over said display period, wherein said multiple intensity scale value G(X,Y) is a grey scale value, and said circuit comprises: -
means for generating the coordinates X,Y of a pixel, means for storing a dither matrix and outputting a specific dither matrix element D(X,Y) in response to the coordinates X,Y of a pixel, means for maintaining a frame count number F in said display period, means for multiplying said multiple intensity scale value G(X,Y) with said frame count number F, means responsive to the dither matrix element D(X,Y), said frame count F, said specific grey scale value G(X,Y) and a product (F * G(X,Y)) of the means for multiplying for the pixel with coordinates X,Y for determining whether said corresponding pixel with coordinates X,Y on said binary display should be illuminated in each frame of said display period, means for adding said product (F * G(X,Y)) and said input intensity value G(X,Y), first means for comparing said product (F * G(X,Y)) with said dither matrix element D(X,Y), second means for comparing said dither element D(X,Y) with said addition ((F * G(X,Y))+G(X,Y)), a third means for comparing said product (F * G(X,Y)) with said addition ((F * G(X,Y))+G(X,Y)), and said circuit generating an output pixel intensity in response to results from said three means for comparing. - View Dependent Claims (11)
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Specification