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
  • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
  • G09G5/22—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators characterised by the display of characters or indicia using display control signals derived from coded signals representing the characters or indicia, e.g. with a character-code memory
  • G09G5/24—Generation of individual character patterns
  • G09G5/28—Generation of individual character patterns for enhancement of character form, e.g. smoothing
• • 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
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
  • G09G5/22—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators characterised by the display of characters or indicia using display control signals derived from coded signals representing the characters or indicia, e.g. with a character-code memory
  • G09G5/24—Generation of individual character patterns
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/04—Structural and physical details of display devices
  • G09G2300/0439—Pixel structures
  • G09G2300/0443—Pixel structures with several sub-pixels for the same colour in a pixel, not specifically used to display gradations
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/04—Structural and physical details of display devices
  • G09G2300/0439—Pixel structures
  • G09G2300/0452—Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2340/00—Aspects of display data processing
  • G09G2340/04—Changes in size, position or resolution of an image
  • G09G2340/0407—Resolution change, inclusive of the use of different resolutions for different screen areas
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2340/00—Aspects of display data processing
  • G09G2340/04—Changes in size, position or resolution of an image
  • G09G2340/0457—Improvement of perceived resolution by subpixel rendering
• • 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
  • G09G3/2003—Display of colours

Definitions

• the present invention relates to methods and apparatus for displaying images, and more particularly, to display methods and apparatus which display an image by representing different portions of the image on each of multiple pixel sub- components, rather than on entire pixels.
• Color display devices have become the principal display devices of choice for most computer users.
• the display of color on a monitor is normally achieved by operating the display device to emit light, e.g., a combination of red, green, and blue light, which results in one or more colors being perceived by the human eye.
• CTR cathode ray tube
• the different colors of light are generated via the use of phosphor coatings which may be applied as dots in a sequence on the screen of the CRT.
• a different phosphor coating is normally used to generate each of the three colors, red, green, and blue resulting in repeating sequences of phosphor dots which, when excited by a beam of electrons will generate the colors red, green and blue.
• pixel is commonly used to refer to one spot in, e.g., a rectangular grid of thousands of such spots.
• the spots are individually used by a computer to form an image on the display device.
• the smallest possible pixel size will depend on the focus, alignment and bandwidth of the electron guns used to excite the phosphors.
• the intensity of the light emitted corresponding to the additive primary colors, red, green and blue, can be varied to get the appearance of almost any desired color pixel. Adding no color, i.e., emitting no light, produces a black pixel. Adding 100 percent of all three colors results in white.
• Fig. 1 illustrates a known portable computer 100, which comprises a housing 101, a disk drive 105, keyboard 104 and a flat panel display 102.
• Portable personal computers 100 tend to use liquid crystal displays (LCD) or other flat panel display devices 102, as opposed to CRT displays. This is because flat panel displays tend to be small and light weight as compared to CRT displays. In addition, flat panel displays tend to consume less power than comparably sized CRT displays making them better suited for battery powered applications than CRT displays. As the quality of flat panel color displays continues to increase and their cost decreases, flat panel displays are beginning to replace CRT displays in desktop applications. Accordingly, flat panel displays, and LCDs in particular, are becoming ever more common.
• LCD liquid crystal displays
• Color LCD displays are exemplary of display devices which utilize multiple distinctly addressable elements, referred to herein as pixel sub-elements or pixel subcomponents, to represent each pixel of an image being displayed.
• each pixel on a color LCD display is represented by a single pixel element which usually comprises three non-square elements, i.e., red, green and blue (RGB) pixel subcomponents.
• RGB red, green and blue
• LCD displays of the known type comprise a series of RGB pixel sub- components which are commonly arranged to form stripes along the display. The RGB stripes normally run the entire length of the display in one direction. The resulting RGB stripes are sometimes referred to as "RGB striping".
• RGB striping Common LCD monitors used for computer applications, which are wider than they are tall, tend to have RGB stripes running in the vertical direction.
• FIG. 2A illustrates a known LCD screen 200 comprising a plurality of rows (R1-R12) and columns (Cl-C 16) which may be used as the display 102. Each row/column intersection forms a square which represents one pixel element.
• Figure 2B illustrates the upper left hand portion of the known display 200 in greater detail. Note in Fig. 2B how each pixel element, e.g., the (Rl, C4) pixel element, comprises three distinct sub-element or sub-components, a red sub-component 206, a green sub-component 207 and a blue sub-component 208.
• each pixel element e.g., the (Rl, C4) pixel element
• Each known pixel subcomponent 206, 207, 208 is 1/3 or approximately 1/3 the width of a pixel while being equal, or approximately equal, in height to the height of a pixel. Thus, when combined, the three 1/3 width pixel sub-components 206, 207, 208 form a single pixel element.
• RGB pixel subcomponents 206, 207, 208 form what appear to be vertical color stripes down the display 200. Accordingly, the arrangement of 1/3 width color sub-components 206, 207, 208, in the known manner illustrated in Figs. 2A and 2B, is sometimes called "vertical striping".
• common column x row ratios include, e.g., 640x480, 800x600, and 1024x768.
• known display devices normally involve the display being arranged in landscape fashion, i.e., with the monitor being wider than it is high as illustrated in Fig. 2A, and with stripes running in the vertical direction.
• LCDs are manufactured with pixel sub-components arranged in several additional patterns including, e.g., zig-zags and a delta pattern common in camcorder view finders. While features of the present invention can be used with such pixel sub- component arrangements, since the RGB striping configuration is more common, the exemplary embodiments of the present invention will be explained in the context of using RGB striped displays.
• each set of pixel sub-components for a pixel element is treated as a single pixel unit. Accordingly, in known systems luminous intensity values for all the pixel sub-components of a pixel element are generated from the same portion of an image. Consider for example, the image represented by the grid 220 illustrated in Fig. 2C. In Fig.
• each pixel sub-component group effectively adds together to create the effect of a single color whose hue, saturation, and intensity depend on the value of each of the three pixel sub-components.
• each pixel subcomponent has a potential intensity of between 0 and 255. If all three pixel subcomponents are given 255 intensity, the eye perceives the pixel as being white. However, if all three pixel sub-components are given a value turning off each of the three pixel sub-components, the eye perceives a black pixel.
• an image to be represented was a red cube with green and blue components equal to zero.
• the apparent position of the cube on the display will be shifted 1/3 of a pixel to the left of its actual position.
• a blue cube would appear to be displaced 1/3 of a pixel to the right.
• known imaging techniques used with LCD screens can result in undesirable image displacement errors.
• the relatively coarse size of standard pixels tends to create aliasing effects which give displayed type characters jagged edges.
• the coarse size of pixels tends to result in the squaring off of serifs, the short lines or ornaments at the ends, e.g., bottom, of strokes which form a typeface character. This makes it difficult to accurately display many highly readable or ornamental typefaces which tend to use serifs extensively.
• Various features of the present invention are directed to utilizing the individual pixel sub-components of a display as independent luminous intensity sources thereby increasing the effective resolution of a display by as much as a factor of 3 in the dimension perpendicular to the direction of the RGB striping. This allows for a significant improvement in visible resolution.
• the present invention is directed to new and improved text, graphics and image rendering techniques which facilitate pixel sub-component use in accordance with the present invention.
• the display of images, including text involves steps that include scan conversion.
• Scan conversion is the process by which geometric representations of images are converted into bitmaps.
• Scan conversion operations of the present invention involve mapping different portions of an image into different pixel sub- components. This differs significantly from known scan conversion techniques where the same portion of an image is used to determine the luminous intensity values to be used with each of the three pixel sub-components which represent a pixel.
• Figure 1 is a diagram of a known portable computer.
• Figure 2A illustrates a known LCD screen.
• Figure 9 illustrates a method of rendering text for display in accordance with one embodiment of the present invention.
• Figure 13 illustrates the scan conversion process applied to the first column of image data illustrated in Fig. 12A in greater detail.
• Figure 14 illustrates a weighted scan conversion operation performed in accordance with one embodiment of the present invention.
• Figure 15 illustrates a high resolution representation of a character to be displayed on a field of pixels.
• Figures 16 illustrates how the character of Fig. 15 would be illustrated using known techniques.
• a number of program modules may be stored on the hard disk 523, magnetic disk 529, (magneto) optical disk 531, ROM 524 or RAM 525, such as an operating system 535, one or more application programs 536, other program modules 537, and/or program data 538 for example.
• a user may enter commands and information into the personal computer 520 through input devices, such as a keyboard 540 and pointing device 542 for example.
• Other input devices such as a microphone, joystick, game pad, satellite dish, scanner, or the like may also be included.
• These and other input devices are often connected to the processing unit 521 through a serial port interface 546 coupled to the system bus.
• input devices may be connected by other interfaces, such as a parallel port, a game port or a universal serial bus (USB).
• a monitor 547 or other type of display device may also be connected to the system bus 523 via an interface, such as a video adapter 548 for example.
• the personal computer 520 may include other peripheral output devices (not shown), such as speakers and printers for example.
• Fig. 7A illustrates a display device 600 implemented in accordance with an embodiment of the present invention.
• the display device 600 is suitable for use in, e.g., portable computers or other systems where flat panel displays are desired.
• the display device 600 may be implemented as an LCD display.
• the display and control logic of the known computer 100 are replaced by the display device 600 and display control logic, e.g., routines, of the present invention to provide a portable computer with horizontal RGB striping and pixel sub-components which are used to represent different portions of an image.
• Each pixel element of the display 600 includes 3 sub-components, a red pixel sub-component 602, a green pixel sub-component 604, and a blue pixel subcomponent 606.
• each pixel sub-component 602, 604, 606 has a height that is equal to, or approximately equal to, 1/3 the height of a pixel and a width equal to, or approximately equal to, the width of the pixel.
• the RGB pixel sub-components are arranged to form horizontal stripes. This is in contrast to the vertical striping arrangement used in the previously discussed monitor 200.
• the monitor 600 may be used, e.g., in particular graphics applications where, because of the application, it is desirable to have a greater vertical, as opposed to horizontal resolution.
• Figure 7B illustrates the upper left hand portion of the display 600 in greater detail. In Fig. 7B, the horizontal RGB striping pattern is clearly visible with the letters R, G and B being used to indicated correspondingly colored pixel subcomponents.
• the application routine 536 which may be, e.g., a word processor application, includes a text output sub-component 801.
• the text output subcomponent 801 is responsible for outputting text information, as represented by arrow 813, to the operating system 535 for rendering on the display device 547.
• the text information includes, e.g., information identifying the characters to be rendered, the font to be used during rendering, and the point size at which the characters are to be rendered.
• the rendering and rasterization routines 807 include a scan conversion subroutine 812 and can also include a scaling sub-routine 808, a hinting sub-routine 810, and a color compensation subroutine 813.
• Scan conversion involves the conversion of the scaled geometry representing a character into a bitmap image.
• Conventional scan conversion operations treat pixels as individual units into which a corresponding portion of the scaled image can be mapped. Accordingly, in the case of conventional scan conversion operations, the same portion of an image is used to determine the luminous intensity values to be used with each of the RGB pixel sub-components of a pixel element into which a portion of the scaled image is mapped.
• Fig. 2C is exemplary of a known scan conversion process which involves sampling an image to be represented as a bitmap and generating luminous intensity values from the sampled values.
• Fig. 6 illustrates an exemplary scan conversion implemented in accordance with one embodiment of the present invention.
• spatially displaced separate image samples 622, 623, 624 of the image represented by the grid 620 are used to generate the red, green and blue intensity values associated with corresponding portions 632, 633, 634 of the bitmap image 630 being generated.
• Sampling the image data and mapping separate image samples 622, 623 and 624 to the red, green, and blue pixel sub-components associated with portions 632, 633, and 634 as shown in Fig. 6 represent examples of acts that correspond to the step of mapping samples to individual pixel sub-components.
• image samples for red and blue are spatially displaced -1/3 and +1/3 of a pixel width in distance from the green sample, respectively.
• white is used to indicate pixel subcomponents which are "turned on” in the bitmap image generated by the scan conversion operation. Pixel sub-components which are not white are "turned off'.
• black text "on” implies that the intensity value associated with the pixel sub-component is controlled so that the pixel sub-component does not output light. Assuming a white background pixel, sub-components which are not "on” would be assigned intensity values which would cause them to output their full light output.
• "on" during scaling is to determine if the center of the scaled image segment, represented by a portion of the scaling grid, being mapped into the pixel sub- component is within the scaled representation of the image to be displayed. For example, in Fig. 12A, when the center of grid segment 1202 was inside the image 1004 (shown in Fig. HA), the pixel sub-component Cl, R5 would be turned on. Another technique is to determine if 50% or more of the scaled image segment being mapped into the pixel sub-component is occupied by the image to be displayed. If it is, then the pixel sub-component is turned "on".
• Hinting when used with the scan conversion operations of the invention, can involve the alignment of a scaled character, e.g., the character 1004 of Fig. 11A within a grid 1102 that is used as part of the subsequent scan conversion operation. It can also involve the distorting of image outlines so that the image better conforms to the shape of the grid.
• the grid can be determined as a function of the physical size of a display device's pixel elements.
• the hinting operation of Fig. 11A results in the hinted image 1014.
• bitmap image 1204. Note how each pixel sub-component of bitmap image columns C1-C4 is determined from a different segment of the corresponding columns of the scaled hinted image 1014. Note also how the bitmap image 1204 comprises a 2/3 pixel height base aligned along a green/blue pixel boundary and a dot that is 2/3 of a pixel in height. Known text imaging techniques would have resulted in a less accurate image having a base a full pixel high and a dot which was a full pixel in size.
• Fig. 12B illustrates a scan conversion operation performed on the hinted image 1018 for display on a display device with vertical striping. Examples of the scaling and hinting operations that can result in image 1018 are described below in reference to Figs. 10B and 11B. To briefly summarize these exemplary scaling and hinting operations, however, Figure 10B illustrates a scaling operation performed on a high resolution representation of the letter i 1002 in anticipation of the display of the letter on a monitor with vertical striping such as the one illustrated in Figs. 2A and 7C. Note that in this example scaling in the horizontal (X) direction is applied at a rate of x3 while scaling in the vertical (Y) direction is applied at a rate of xl .
• Figure 11B illustrates a hinting operation that results in the alignment of scaled character 1008 within grid 1104 that is used as part of the subsequent scan conversion operation. It can also involve the distorting of image outlines so that the image better conforms to the shape of the grid.
• the hinting operation of Fig. 1 IB results in the hinted image 1018.
• the scan conversion operation of Fig. 12B results in the bitmap image 1203.
• bitmap image 1203 comprises a 2/3 pixel width stem with a left edge aligned along a red/green pixel boundary. Notice also that a dot that is 2/3 of a pixel in width is used.
• Known text imaging techniques would have resulted in a less accurate image having a stem a full pixel wide and dot a full pixel in size.
• Figure 13 illustrates the scan conversion processes performed to the first column of the image 1014, shown in Fig. 12 A, in greater detail.
• one segment of the image 1014 is used to control the luminous intensity value associated with each pixel sub-component. This results in each pixel sub-component being controlled by the same size portion of the image 1014.
• Weighting may be applied during the scan conversion operation. When weighting is applied, different size regions of the scaled image may be used to determine whether a particular pixel sub-component should be turned on or off or to a value in between (as in the case of gray scaling). As discussed above, the human eye perceives light intensity from different color light sources at different rates.
• Green contributes approximately 60%, red approximately 30% and blue approximately 10% to the perceived luminance of a white pixel which results from having the red, green and blue pixel sub-components set to their maximum luminous intensity output.
• weighting is used during scan conversion so that 60% of the scaled image area that is mapped into a pixel is used to determine the luminous intensity of the green pixel sub-component, a separate 30% of the scaled image area that is mapped into the same pixel is used to determine the luminous intensity of the red pixel sub-component, and a separate 10% of the scaled image area that is mapped into the same pixel is used to determine the luminous intensity of the blue pixel sub-component.
• the image is scaled in the direction perpendicular to the striping at a rate which is ten times the rate of scaling in the direction of the striping. This is done to facilitate a weighted scan conversion operation.
• the scaled image is then processed during scan conversion using a weighted scan conversion operation, e.g., of the type described above.
• Figure 10A depicts an image 1002 that has been scaled by a factor of three in the vertical direction and a factor of one in the horizontal direction.
• Fig. 14 illustrates performing a weighted scan conversion operation on the first column 1400 of a scaled hinted version of the image 1002 which has been scaled by a factor of 10 in the vertical direction and a factor of one in the horizontal direction.
• the portion of the hinted image which corresponds to a single pixel comprises 10 segments.
• the first set of three segments of each pixel area of the scaled image are used to determine the luminous intensity value of a red pixel sub-component corresponding to a pixel in the bitmap image 1402.
• the next set of six segments of each pixel area of the scaled image 1400 are used to determine the luminous intensity value of a green pixel subcomponent corresponding to the same pixel in the bitmap image 1402. This leaves the last segment of each pixel area of the scaled image 1400 for use in determining the luminous intensity value of the blue pixel sub-component. As illustrated in Fig. 14, this process results in the blue pixel sub-component of column 1, row 4 and the red pixel sub-component of column 1, row 5 of the bitmap image 1402 being turned “on” with the remaining pixel sub-components of column 1 being turned “off”.
• the scan conversion operation involves independently mapping portions of the scaled hinted image into corresponding pixel sub-components to form a bitmap image.
• the intensity value assigned to a pixel sub-component is determined as a function of the portion of the scaled image area being mapped into the pixel subcomponent that is occupied by the scaled image to be displayed.
• a pixel sub-component can be assigned an intensity value between 0 and 255, 0 being effectively off and 255 being full intensity
• a scaled image segment grid segment
• a pixel sub-component being assigned an intensity value of 127 as a result of mapping the scaled image segment into a corresponding pixel subcomponent.
• the neighboring pixel sub- component of the same pixel would then have its intensity value independently determined as a function of another portion, e.g., segment, of the scaled image.
• the scan conversion operations of the invention can be used with the rendering and rasterization routines 807 of Figure 9 to render text for display in accordance with one embodiment of the present invention.
• the routines 807 begin in step 902 wherein the routines are executed, e.g., under control of the operating system 535, in response to the receipt of text information from the application 536.
• input is received by text rendering and rasterization routines 807.
• the input includes text, font, and point size information 905 obtained from the application 536.
• the input includes scaling information and/or foreground/background color information and pixel size information 815 obtained, e.g., from monitor settings stored in memory by the operating system.
• the input also includes the data 806 which includes a high resolution representation, e.g., in the form of lines, points and/or curves, of the text characters to be displayed.
• step 910 the scaling subroutine 808 may be used to perform a scaling operation.
• Non-square scaling can be performed as a function of the direction and/or number of pixel subcomponents included in each pixel element.
• the high resolution character data 806 e.g., the line and point representation of characters to be displayed as specified by the received text and font information, is scaled in the direction perpendicular to the striping at a greater rate than in the direction of the striping. This allows for subsequent image processing operations to take advantage of the higher degree of resolution that can be achieved by using individual pixel sub-components as independent luminous intensity sources in accordance with the present invention.
• step 912 in which hinting of the scaled image may be performed, e.g., by executing the hinting subroutine 810.
• the term grid-fitting is sometimes used to describe the hinting process.
• Hinting involves the alignment of a scaled character, e.g., the character 1004, 1008 within a grid 1102, 1104 that is used as part of a subsequent scan conversion operation. It also involves the distorting of image outlines so that the image better conforms to the shape of the grid.
• the grid is determined as a function of the physical size of a display device's pixel elements. Details of exemplary hinting operations that can be used with the scan conversion operations of the invention are disclosed in U.S. Patent Application Serial No. 09/168,012 at, for example, Figures 11A, 11B, and the accompanying text.
• step 914 a scan conversion operation, such as those disclosed herein, is performed in accordance with the present invention, e.g., by executing the scan conversion sub-routine 812.
• the processed bitmap 918 is output to the display adapter 814 and operation of the routines 807 is halted pending the receipt of additional data/images to be processed.
• Figure 15 illustrates a high resolution representation of character n to be rendered superimposed on a grid representing an array of 12x12 pixels with horizontal striping.
• Figure 16 illustrates how the character n illustrated in Fig. 15 would be rendered using conventional display techniques and full size pixel elements each including three pixel sub-components. Note how the full pixel size limitation results in relatively abrupt transitions in shape at the ridge of the letter resulting in aliasing and a relatively flat top portion.
• Figure 17 illustrates how rendering of the letter n can be improved in accordance with the present invention by using a 2/3 pixel height base.
• the base is formed using 2 pixel sub-components as opposed to all three pixel sub-components in row 10, col. 1-4 and 8-10.
• Figure 18 illustrates how the ridge of the letter n can be reduced in thickness from one pixel in thickness to a 2/3 pixel thickness in accordance with the present invention.
• Figure 19 illustrates how the base of the letter n can be reduced, in accordance with the present invention, to a minimal thickness of 1/3 that of a pixel. It also illustrates how portions of the ridge of the letter n can reduced to a thickness of 1/3 that of a pixel.
• Figure 20 illustrates how the letter n can be illustrated, in accordance with the present invention, with a base and ridge having a thickness of 1/3 that of a pixel.
• Fig. 4 depicts a computerized electronic book device 400.
• the electronic book 400 comprises first and second display screens 402, 404 for displaying odd and even pages of a book, respectively.
• a display device of the type illustrated in Fig. 7C, for example, may be used as the displays 402, 404 of the electronic book 400 of Fig. 4.
• the electronic book 400 further comprises an input device, e.g., keypad or keyboard 408 and a data storage device, e.g., CD disk drive 407.
• a hinge 406 is provided so that the electronic book 400 can be folded protecting the displays 402, 404 when not in use.
• An internal battery may be used to power the electronic book 400.
• other portable computer embodiments of the present invention may be powered by batteries.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Liquid Crystal Display Device Control (AREA)
• Image Processing (AREA)
• Liquid Crystal (AREA)
• Controls And Circuits For Display Device (AREA)
• Facsimile Image Signal Circuits (AREA)
• Color Image Communication Systems (AREA)
• Editing Of Facsimile Originals (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)
• Color Television Image Signal Generators (AREA)

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