Classifications

• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
  • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
  • G09G3/3607—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/2007—Display of intermediate tones
  • G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/2007—Display of intermediate tones
  • G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
  • G09G3/2022—Display of intermediate tones by time modulation using two or more time intervals using sub-frames
  • G09G3/2025—Display of intermediate tones by time modulation using two or more time intervals using sub-frames the sub-frames having all the same time duration
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/2007—Display of intermediate tones
  • G09G3/2044—Display of intermediate tones using dithering
  • G09G3/2051—Display of intermediate tones using dithering with use of a spatial dither pattern

Definitions

• the present invention generally relates to processes for providing multi-color images on opto ⁇ electronic display devices; more particularly, the present invention relates to processes for producing 10 multi-color shaded images in successive frames of video information on opto-electronic display devices such as flat-panel LCDs (liquid crystal diodes) and similar display devices.
• opto-electronic display devices such as flat-panel LCDs (liquid crystal diodes) and similar display devices.
• the opto-electronic displays such as flat-panel LCDs (liquid crystal diodes) and similar display devices that are employed with laptop computers.
• LCDs and other flat-panel display devices differ from CRT devices in two important aspects. 25 First, in operation of a CRT device, an electron beam is driven to scan rapidly back and forth across a screen to sequentially energize selected picture- element or "pixel" locations along horizontal scanning lines; the net effect of a complete raster of scans is
• the horizontal scanning lines are organized by synchronizing signals, with each frame containing a fixed number of horizontal lines.
• the frames are reproduced at a standard rate; for example, the frame repetition rate might be sixty frames per second.
• LCDs and similar flat-panel display screens differ from CRT devices in that the illumination intensity (i.e., brightness) at the pixel locations cannot be varied. Instead, the illumination intensity at pixel locations on a flat-panel display screen is either "on” or “off". (For present purposes, a pixel location will be considered “on” when the pixel location is illuminated, and, conversely, a pixel location will be considered “off” when it is not illuminated.) Thus, when a flat-panel display screen is fully illuminated — that is, each pixel location is in its "on” state — the screen will have uniform brightness. (In the following, the term “binary display device” refers to display devices whose picture elements have only two display states — either an "on” or an “off” state.)
• Frame modulation techniques basically employ the principle that the frequency with which a pixel location is illuminated determines its perceived brightness and, therefore, its perceived shading. For example, to display a 25% black tone using simple frame modulation, a display element is made active (or inactive) in one-quarter of the frames; similarly, to display a tone of 75% black, a display element would be made active (or inactive) in three-quarters of the frames.
• frame modulation techniques are based upon the principle that, for a picture element having only an active state and an inactive state, when the picture element is made active (or inactive) in a certain fraction of successive frames occurring within a short period of time, the human eye will perceive the picture element as having a tone which is intermediate to tones that are presented when the display elements were constantly active (or constantly inactive) .
• the intermediate tones are determined by the percentage of frames in which the display element is active (or inactive) . Accordingly, when modulation is performed over a sixteen-frame period, then sixteen different tones are simulated.
• frame modulation techniques take advantage of persistence and averaging properties of human vision according to which a display element turned on and off at a sufficiently rapid rate is perceived as being continually on and as having a display intensity proportional to the on/off duty cycle of the display element.
• frame modulation techniques for producing shading on binary display devices tend to create displays in which the human eye detects considerable turbulence or "display noise".
• the present invention generally speaking, relates to processes for producing color shading in multi-color images that are presented in successive frames of video information on flat-panel LCD (liquid crystal diode) displays and similar binary display devices. More particularly, the present invention provides a method for simulating various color shades in images on a display device that has an array of picture elements each having only two display states, an "on" state and an "off” state.
• the present invention provides a process for producing shading in multi-color images that are presented in successive frames of video information on flat-panel LCD (liquid crystal diode) displays and similar binary display devices while reducing display noise to a minimum.
• LCD liquid crystal diode
• Each pixel location includes illumination elements each of a different color, for example, red, green and blue illumination elements.
• the method of the present invention is accomplished by modulating an on/off duty cycle of one or more illumination elements of each picture element of the array of picture elements during a multi-frame display sequence according to attribute information of respective picture element data to be displayed.
• the timing of on/off and off/on state transitions of the illumination elements is coordinated within predetermined neighborhoods throughout the array of picture elements such that the state transitions occur substantially uniformly in space and time within a display neighborhood during the multi-frame display sequence.
• the present invention takes further advantage of the visual averaging property by causing state transitions to occur substantially uniformly in space and time within each neighborhood throughout the array of picture elements during a multi-frame display sequence.
• no individual state transitions, which by themselves constitute only display noise, are perceived; instead, a coherent pattern of state transitions blending is seen that effectively simulates non-monochrome image displays.
• any pixel location can have any one of 4096 different color shades. This is accomplished even though each illumination element at each pixel location can have one of two states (i.e., either "on” or "off") at any given instant, and, therefore, each pixel location can have any one of eight colors (i.e., 2 3 colors) at any given instant.
• Figure 1 is a pictorial representation of a display screen having an image field
• Figure 2A shows a display neighborhood of the image field of the display screen of Figure 1, with the display neighborhood being drawn to a highly enlarged scale for purpose of convenience in describing the process of the present invention
• Figure 2B shows in greater detail the display neighborhood of Figure 2A, in particular showing the different illumination elements included in each picture element;
• Figure 3 shows an example of a look-up table for determining an entire frame modulation sequence for each of a number of display tones within a display neighborhood as in Figure 2;
• Figure 4 shows the display neighborhood of Figure 2 and a preferred pixel transition order within each neighborhood according to the present invention.
• Figure 1 shows an image field 13 that appears on the display screen of a flat-panel LCD or similar binary display device.
• These display devices are characterized by the fact that their pixel locations have only two display states — that is, the pixel locations are either illuminated or are not illuminated.
• the image field is subdivided into two-dimensional, uniformly-sized display neighborhoods, such as will be discussed below in conjunction with Figures 2-4.
• the display neighborhood 17 in Figure 2A is shown to be four pixels wide by four pixels high; in other words, display neighborhood 17 is a square that encompasses sixteen pixel locations.
• the sixteen pixel locations in display neighborhood 17 are labelled as locations "a” through “p".
• Figure 3 shows an example of a look-up table for determining a temporal pattern for illuminating pixel locations in the display neighborhoods to produce selected shades.
• the temporal pattern over which a given illumination element at a pixel location is illuminated is expressed in terms of a "frame sequence". Within a frame sequence, the number of times that a given illumination element at a pixel location is illuminated will determine its brightness and, therefore, will create an appearance of its shade relative to other pixel locations.
• the look-up table in Figure 3 is used in conjunction with a frame modulation process whereby the frequency with which a pixel location is illuminated will determine its perceived brightness and, therefore, its shading. For example, if pixel location "a" in Figure 2A is illuminated only once over a sequence of sixteen frames, that pixel location will appear as a dark shade relative to other pixel locations that are illuminated more frequently over the same frame sequence. In a similar way, if pixel location "e” is illuminated three times over a sequence of sixteen frames, that pixel location will appear as a lighter shade (brighter) relative to pixel location "a".
• the vertical axis indicates shading, from light to dark, over sixteen different shades.
• the upper rows of the look-up table show pixel illumination patterns that provide the appearance of lighter shades.
• the pixel illumination patterns in the lower rows of the look-up table conversely, provide the appearance of darker shades.
• the lightest shade will be referred to as shade #1, the next lightest shade will be referred to as shade #2, and so forth.
• the horizontal axis in the look-up table in Figure 3 indicates the frame number. Because a sixteen-frame sequence has been selected in this example, the first column in the table represents the first frame of the sixteen-frame sequence, the second column represents the second frame of the sixteen-frame sequence, and so forth.
• Each square area in the look-up table in Figure 3 shows the state of the pixel locations in the display neighborhood for a selected shading at a given frame number.
• the look-up table indicates that shade #1 is produced at pixel location "a” by illuminating that pixel location only during the eighth frame of a sixteen-frame sequence.
• the look-up table indicates that shade #1 is produced at pixel location "f” by illuminating that pixel location only during the fifteenth frame of the sixteen-frame sequence.
• shade #1 is produced at pixel location "d” by illuminating that pixel location only during the sixteenth frame.
• the look-up table in Figure 3 indicates that shade #3 is produced at pixel location "e” by illuminating that pixel location during the fourth, tenth, and fifteenth frames of the sixteen-frame sequence.
• the look-up table similarly indicates that shade #4 is produced at pixel location "b” by illuminating that pixel location during the first, fifth, ninth and thirteenth frames of the sixteen-frame sequence.
• pixel location "e” will appear lighter than pixel location "a”, and pixel location "b” will appear as still lighter — and this is a result of the fact that pixel location "a” is illuminated once in the sixteen-frame sequence, while pixel location “e” is illuminated three times in the sixteen-frame sequence, and pixel location "b” is illuminated four times in the sixteen-frame sequence.
• the limit obviously, is to illuminate a pixel location "b” sixteen times in the sixteen-frame sequence.
• FIG. 3 it will be seen that, as a general rule, adjacent pixel locations that have the same shade within any one of the display neighborhoods are illuminated with different temporal patterns over a frame sequence.
• the look-up table indicates that pixel location "a” is illuminated only during the eighth frame of the sixteen-frame sequence and that pixel location "b” is illuminated only during the first frame of the sequence.
• the look-up table indicates that pixel location "e” is illuminated during the fourth, tenth, and fifteenth frames of the sixteen-frame sequence, while pixel location "f” is illuminated during the fifth, eleventh, and sixteenth frames to produce the same shade.
• the look-up table in Figure 3 indicates that the three pixel locations "b", “h” and “o” are to be illuminated during the first frame of the sixteen-frame sequence; that the three pixel locations "g", “i” and “p” are to be illuminated during the second frame; that pixel locations "a”, "c” and “j” are to be illuminated during the third frame; and so forth.
• This example can be extended so that a display neighborhood can have any one of sixteen different grey scale shades.
• the same look ⁇ up table can be applied to all of the display neighborhoods within an image field.
• Figure 4 shows an example of a pixel transition order within a display neighborhood. This example is best understood by considering the case wherein a display neighborhood is to be uniformly shaded with shade #1.
• the look-up table of Figure 3 indicates that the single pixel location "b" is illuminated during a first frame of the sixteen- frame sequence; that the pixel location "h” is illuminated during the second frame; that the pixel location "o” is illuminated during the third frame; and so forth.
• the same pixel transition order can be seen in Figure 4, and, in fact, that diagram was used as the basis for constructing the look-up table in Figure 3.
• the illumination conditions described in the preceding paragraph can be accomplished by simultaneously illuminating all three illumination elements (i.e., the red, green and blue illumination elements) at each of the pixel locations. Also, the conditions described in the preceding paragraph can be accomplished by selecting only one of the illumination elements for illumination, as long as the same color element is always selected.
• each illumination element at each pixel location can have one of two states (i.e., either "on” or "off") .
• each pixel location can have any one of eight colors (i.e., 2 3 colors).
• each color can be controlled, as described above, to have one of sixteen different shades. (A seventeenth shade is either all black or all white.)
• the illumination elements have colors red, green and blue
• any one of the sixteen red shades can be combined with any one of the sixteen green shades — for a total of 16 2 , or 256 shades. Furthermore, any one of those 256 shades can be combined with any one of the sixteen blue shades — for a total of 4096 shades.
• a given display neighborhood is not usually uniformly shaded, but, instead, shading is to be varied from pixel-to-pixel within the display neighborhood.
• the look-up table of Figure 3 also determines how pixel illumination sequences are selected when the shading at a given pixel location changes —that is, when the shading at a given pixel location is to be made lighter or darker.
• pixel location "p" has shade #1 and that a transition to shade #2 is to occur at the beginning of the second frame sequence where each sequence comprises sixteen frames.
• pixel location "p" is illuminated only in the sixth frame of the first frame sequence.
• pixel location "p” is not illuminated again until the third frame of the second frame sequence; then, that pixel location is illuminated again in the eleventh frame, and so forth.
• the present invention provides a method for producing multi-color shaded images in successive frames of video information on opto-electronic display devices such as flat-panel LCDs (liquid crystal diodes) and similar display devices that do not intrinsically provide display shades.
• opto-electronic display devices such as flat-panel LCDs (liquid crystal diodes) and similar display devices that do not intrinsically provide display shades.
• no individual state transitions, which by themselves constitute only display noise, are perceived; instead, a coherent pattern of state transitions blending is seen that effectively simulates multi-color image displays.

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• Crystallography & Structural Chemistry (AREA)
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• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Liquid Crystal Display Device Control (AREA)
• Ultra Sonic Daignosis Equipment (AREA)
• Video Image Reproduction Devices For Color Tv Systems (AREA)

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• 1993
  • 1993-04-07 WO PCT/US1993/003326 patent/WO1993020549A1/fr active IP Right Grant
  • 1993-04-07 AT AT93912159T patent/ATE167586T1/de active
  • 1993-04-07 EP EP93912159A patent/EP0635155B1/fr not_active Expired - Lifetime
  • 1993-04-07 DE DE69319236T patent/DE69319236T2/de not_active Expired - Lifetime
  • 1993-04-07 JP JP5517786A patent/JP2727029B2/ja not_active Expired - Fee Related
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