JP5231697B2 - Method and computer system for improving the resolution of displayed images - Google Patents

Abstract

Methods and apparatus for sampling image data (620) and mapping the samples (622, 623, 624) to pixel sub-components (632, 633, 634) which form a pixel element of an LCD display so that each pixel sub-component (632, 633, 634) has a different portion of the image (620) mapped thereto. The methods can be used with conventional color LCD displays that include pixels consisting of three non-overlapping red, green and blue rectangular pixel sub-elements or sub-components. The pixel sub-components (632, 633, 634) can be arranged on the display device to form horizontal or vertical stripes of individual colors. The separately-controllable nature of individual RGB pixel sub-components is used to effectively increase a screen's resolution in the dimension perpendicular to the dimension in which the screen is striped. A scan conversion process maps samples (622, 623, 624) of the image data (620) to individual pixel sub-components, resulting in each of the pixel sub-components representing a different portion of the image. The color values are independently generated for each of the red, green, and blue pixel sub-components based on different portions of the image (620), rather than the color values for the entire pixel being generated based on a single sample or the same portion of the image.

Description

(Background of the Invention)
1. Related Application This application is a continuation of US patent application 09 / 168,012 entitled “Method and Apparatus for Displaying Images such as Text” filed Oct. 7, 1998. And continuation of US patent application 09 / 240,654, filed January 29, 1999, entitled “Method and Apparatus for Performing Image Rendering and Rasterization Operations”. Both applications are hereby incorporated by reference into the text.
2. The present invention relates to an image display method and apparatus, and more particularly to a method and apparatus for displaying an image by representing different portions of the image on each of a number of pixel subcomponents rather than all pixels. .
3. Background of the Invention Color display devices have become the primary display device of choice for most computer users. To perform color display on a monitor, the display device is typically operated to emit a combination of light, eg, red, green, and blue light, to obtain one or more colors that are perceived by the human eye. To be able to.

  In cathode ray tube (CRT) display devices, to produce different colors of light, phosphor coatings can be used and deposited as a series of dots on a CRT screen. Typically, to generate each of the three colors, red, green, and blue, different phosphor coatings are used to form a repeating sequence of phosphor dots. When these are excited by an electron beam, they produce red, green and blue colors.

  The term pixel is commonly used to mean a spot in a rectangular grid of, for example, thousands of spots. The spots are used individually for the computer to form an image on the display device. In a color CRT that cannot address a single triad of red, green and blue emitter dots, the smallest pixel size possible is the focus and alignment of the electron gun used to excite the emitter. And bandwidth. In various configurations known to CRT displays, the light emitted from one or more triads of red, green and blue phosphor dots is blended together to give the appearance of a single color light source at a distance. In many cases.

  In color displays, the appearance of almost any desired color pixel can be obtained by varying the intensity of the emitted light corresponding to the additive primary color, red, green and blue. When no color is added, that is, when no light is emitted, black pixels are generated. If you add all three colors at 100 percent, you get white.

  FIG. 1 shows a known portable computer 100 comprising a housing 101, a disk drive 105, a keyboard 104 and a flat panel display 102.

  The portable personal computer 100 often uses a liquid crystal display (LCD) or other flat display device 102 instead of a CRT display. This is because flat panel displays are often smaller and lighter than CRT displays. In addition, flat panel displays are often more suitable for battery-powered use than CRT displays because they consume less power than comparable CRT displays.

  As the quality of flat panel color displays continues to improve and its price decreases, flat panel displays are beginning to replace CRT displays in desktop applications. Accordingly, flat panel displays, particularly LDCs, are becoming more common than ever.

  Over the years, most image processing techniques have been developed and optimized for display on CRT display devices, including the generation and display of fonts, eg character sets, on computer screens.

  Unfortunately, existing text display routines do not take into account the physical characteristics unique to flat panel display devices. These physical characteristics are very different from those of the CRT apparatus, particularly with respect to the physical characteristics of the RGB color light source.

  A color LCD display is an example of a display device that utilizes a number of separate addressable elements, referred to herein as pixel sub-elements or pixel sub-components, to represent each pixel of an image to be displayed. Typically, each pixel on a color LCD display is represented by a single pixel element, often consisting of three non-square elements, namely red, green and blue (RGB) pixel subcomponents. Thus, a set of RGB pixel subcomponents together form a single pixel element. A known type of LCD display comprises a series of RGB pixel subcomponents and is generally configured to form a stripe along the display. RGB stripes usually span the entire length of the display in one direction. The obtained RGB stripe may be referred to as “RGB striping”. A general LCD monitor used for computer use is wider in the horizontal direction than in the vertical direction, and the RGB stripes often extend in the vertical direction.

  FIG. 2A shows a known LCD screen 200 comprised of a plurality of rows (R1-R12) and columns (C1-C16) that can be used as display 102. FIG. Each row / column intersection forms a square representing one pixel element. FIG. 2B shows the upper left portion of the known display 200 in more detail.

  Note that in FIG. 2B, each pixel element, eg, (R1, C4) pixel element, consists of three distinct sub-elements or sub-components: a red sub-component 206, a green sub-component 207, and a blue sub-component 208. Keep it. Each known sub-component 206, 207, 208 is one third or about one third of the pixel width, while its height is equal to or approximately equal to the pixel height. Thus, when combined, the three 1/3 wide pixel subcomponents 206, 207, 208 form a single pixel element.

  As shown in FIG. 2A, one known configuration of RGB pixel subcomponents 026, 207, 208 forms what appears as a vertical color stripe toward the bottom of the display 200. Thus, in the known form shown in FIGS. 2A and 2B, the array of 1/3 wide color sub-components 206, 207, 208 can also be referred to as "vertical striping".

  For illustration purposes only FIG. 2A shows only 12 rows and 16 columns, but typical column × row ratios include, for example, 640 × 480, 800 × 600, and 1024 × 768. A known display device is usually a landscape-arranged display, that is, a monitor whose width is wider than vertical and stripes run in the vertical direction, as shown in FIG. 2A.

  When manufacturing an LCD, the pixel sub-components are arranged in several additional patterns. These patterns include, for example, zigzag patterns and delta patterns common in camcorder view finders. While the features of the present invention can be used with such pixel sub-component arrangements, an exemplary embodiment of the present invention is described in connection with an RGB striped display, as RGB striping configurations are more common. I decided to.

  Conventionally, each pixel subcomponent set for one pixel element is treated as a single pixel unit. Thus, in known systems, the light intensity values for all pixel subcomponents of a pixel element originate from the same part of the image. For example, consider an image represented by a grid 220 shown in FIG. 2C. In FIG. 2C, each square represents an area of the image represented by a single pixel element, eg, the corresponding square red, green and blue pixel subcomponents of the grid 230. In FIG. 2C, a hatched circle is used to represent a single image sample that generates a light intensity value. Note that in known systems, a single sample 22 of the image 220 is used to generate luminosity values for each of the red, green, and blue pixel subcomponents 232, 233, 234. Thus, known systems typically use RGB pixel sub-components as a group to generate a single color pixel corresponding to a single sample of the image to be represented.

  The light from each pixel sub-component group actually adds together to give a single color effect. Its hue, saturation, and intensity are determined by the value of each of the three pixel subcomponents. For example, each pixel sub-component can have an intensity between 0 and 255. If all three pixel subcomponents are given an intensity of 255, the eye will perceive the pixel as white. However, if all three pixel subcomponents are given a value that turns off the three pixel subcomponents, the eye will recognize a black pixel. By varying the respective intensity of each pixel subcomponent, millions of colors can be generated between these two extreme values.

  In known systems, a single sample is mapped to three pixel subcomponents, each having a width of 1/3 of a pixel, resulting in spatial displacement of the left and right pixel subcomponents. This is because the center of these elements is 1/3 from the center of the sample.

  For example, consider the case where the image to be represented is a red cube and the green and blue components are equal to zero. As a result of the displacement between the sample and the green image subcomponent, when displayed on an LCD display of the type shown in FIG. 2A, the apparent position of the cube on the display is 1/3 of a pixel to the left of its actual position. It will shift to. Similarly, the blue cube will appear to be displaced to the right by 1/3 of the pixel. Thus, known imaging techniques used for LCD screens can cause undesirable image displacement errors.

  Text characters represent a type of image and are particularly difficult to display with high precision at typical flat panel display resolutions of 72 or 96 dots per inch (dpi). Such display resolution is far inferior to 600 dpi, which is compatible with most printers, and higher resolutions found in commercial printed documents such as books and magazines.

  Due to the relatively low display resolution of most video display devices, especially with common text sizes such as 10, 12, and 14 point fonts, not enough pixels are available to draw a smooth character shape. With such a common text rendering size, the different sizes and weights of the same typeface, for example, the gradation between thicknesses, is much coarser than their printed counterparts.

  The relatively coarse size of a standard pixel is prone to alias effects and the edges of the displayed type character are jagged. For example, coarse size pixels often squaring off lines, short lines or decorations at the end of the stroke that forms the typeface character, for example, the bottom. This makes it difficult to accurately display many very interesting or decorated typefaces that tend to use lines widely.

  Such a problem is particularly noticeable in a character stem, for example, a thin vertical portion. Since a pixel is the minimum display unit of a conventional monitor, a character's stem cannot be displayed using a conventional technique with less than the weight of one pixel's stem. Furthermore, the stem weight can only be increased for one pixel at a time. Therefore, the stem weight jumps with a width of 1 to 2 pixels. In many cases, a one-pixel wide character stem is too thin, while a two-pixel wide character stem is too thick. In order to create a typeface of a small character on the display screen with a bold face, it is necessary to change the stem weight from 1 pixel to 2 pixels, so the difference in weight between the two is 100%. In printing, bold is typically only 20 or 30 percent heavier than its normal or roman face equivalent. In general, this “one pixel, two pixel” problem is treated as an inherent characteristic of a display device, and is simply accepted.

  Conventional research in the field of character display has been partly focused on the development of anti-aliasing technology designed to improve the display of characters on CRT displays. A commonly used anti-aliasing technique must use a gray halftone for pixels that include the edges of the character. In fact, this causes blurring in the shape, leading to a reduction in the spatial frequency of the edges, but improves the approximation of the intended character shape. While known anti-aliasing techniques can significantly improve the quality of characters displayed on CRT display devices, many of these techniques have CRTs for pixel subcomponent arrangements when applied to LCD display devices. Since it is significantly different from the display, the effect cannot be obtained.

  The anti-aliasing technology has helped with the aliasing problem associated with displaying text at a relatively low resolution, at least on a CRT display, but it displays pixel stem issues and character stem width with high accuracy. The problem of not being able to do so was an invariant characteristic of display devices prior to the present invention, which was thought to be other than withstanding.

  In view of the foregoing, there is a clear need for new and improved methods and apparatus for displaying text on flat panel display devices. Desirably, at least some of the new methods are suitable for use with existing display devices and computers. Further, it is desirable that at least some of the methods and apparatuses are aimed at improving the quality of text displayed on a new computer using, for example, a new display device and / or a new method for displaying text.

Displaying text, which is a special case of graphics, is a major concern in many computer applications, but other graphics, geometric shapes, such as circles, squares, etc., and captured images such as photographs There is also a need for an improved method and apparatus for accurately and clearly displaying the image.
(Outline of the present invention)
The present invention is directed to an image display method and apparatus for displaying an image by representing different portions of the image on each of a number of pixel subcomponents rather than all pixels.

  The inventor of the present application has recognized the well-known principle that the human eye is more sensitive to luminance edges where the light intensity changes than to chrominance edges where the color intensity changes. This is the reason why, for example, it is very difficult to read red text on a green background. The inventor has also recognized the well-known principle that the eye is not equally sensitive to red, green and blue colors. In fact, out of 100 percent luminous intensity in a completely white pixel, the red pixel subcomponent contributes about 30%, green 60% and blue 10% to the total perceived luminance.

  Various features of the present invention allow the effective resolution of the display to be as high as three times in the dimension perpendicular to the direction of RGB striping by utilizing the individual pixel subcomponents of the display as independent luminous intensity sources. The purpose is to increase. This allows a significant improvement in the visible resolution.

  Although the method of the present invention may involve some degradation in chrominance quality compared to known display technologies, as described above, the human eye is more sensitive to luminance edges than chrominance. . Thus, the present invention can significantly improve the quality of an image compared to conventional rendering techniques, even considering the adverse effects of the present technique on color quality.

  As mentioned above, known monitors often use vertical striping. Character stems appear vertically and when rendering horizontally flowing text, the ability to accurately control the thickness of vertical lines is often more important than the ability to control the thickness of horizontal lines. .

  With this in mind, at least for text applications, it is often desirable to have the maximum resolution of the monitor in the horizontal direction rather than the vertical direction. Accordingly, various display devices implemented in accordance with the present invention utilize vertical RGB striping rather than horizontal. Thus, such a monitor, when used in accordance with the present invention, has a higher resolution in the horizontal direction than in the vertical direction. However, the present invention can be similarly applied to a horizontal RGB striping monitor, and the vertical resolution can be increased as compared with the conventional image rendering technology.

  In addition to a new display device suitable for use when treating a pixel subcomponent as an independent light source, the present invention provides new and improved text, graphics and images that facilitate the use of the pixel subcomponent according to the present invention. Rendering technology is also aimed.

Displaying an image containing text involves several steps, including scan conversion.
Scan conversion is the process of converting a geometric representation of an image into a bitmap. The scan conversion operation of the present invention involves mapping different parts of the image to different pixel subcomponents. This is quite different from known scan conversion techniques that use the same portion of the image to determine the light intensity value and use it with each of the three pixel subcomponents representing one pixel.

  The scan conversion operations of the present invention can be used with other operations including image scaling, hinting, color processing operations, such as pixel sub-component boundaries in the image and flat panel display device. It takes into account the separately controllable nature of the pixel subcomponent.

Numerous additional features, embodiments and advantages of the method and apparatus of the present invention are set forth in the following detailed description.
(Detailed explanation)
As described above, the present invention displays images, eg, text and / or graphics, on a display device by representing different portions of the image on each of a number of pixel subcomponents rather than all pixels. Relates to a method and apparatus.

The various methods of the present invention attempt to use each pixel subcomponent as a separate, independent light intensity source, rather than treating a set of RGB pixel subcomponents that make up a pixel as a single light intensity unit. . This allows an RGB horizontal or vertical striped display device to be treated as having an effective resolution up to three times higher than the striping dimension in a dimension perpendicular to the striping direction. Various devices of the present invention are directed to display devices and control devices that take advantage of the ability to individually control pixel subcomponents.
A. Exemplary Computing and Hardware Environment FIG. 5 and the following discussion provide a brief overall description of example devices that can implement at least some aspects of the present invention. The various methods of the present invention are generally described in the context of computer-executable instructions, eg, program modules, that are executed by a computing device such as a personal computer. Other aspects of the invention are described with respect to physical hardware, such as display device components and display screens.

  The methods of the present invention can also be performed on apparatus other than the specific computer devices described herein. Program modules can include routines, programs, objects, components, data structures, etc., that perform tasks (tasks) or implement specific abstract data types. Moreover, those skilled in the art will recognize that at least some of the aspects of the invention may be practiced with other configurations. Among them are handheld devices, multiprocessor systems, consumer or programmable consumer electronics using microprocessors, network computers, minicomputers, set top boxes, mainframe computers For example, displays used in automobiles, aircraft, industrial applications and the like. Also, at least some of the aspects of the invention can also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules can be located in local and / or remote memory storage devices.

  With reference to FIG. 5, an exemplary apparatus 500 for implementing at least some of the aspects of the present invention includes a general purpose computing device. The personal computer 520 can include a system bus 523 that couples various system components including a processing unit 521, system memory 522, and system memory through processing unit 521. The system bus 523 may be any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. The system memory may include read only memory (ROM) 524 and / or random access memory (RAM) 525. A basic input / output system 526 (BIOS) that includes basic routines responsible for transferring information between elements within the personal computer 520, such as during startup, can be stored in the ROM 524. Further, the personal computer 520 includes a hard disk drive 527 that reads / writes data from / to a hard disk (not shown), a magnetic disk drive 528 that reads / writes data from / to a magnetic disk (529 (eg, removable)), and a compact disk. Or it may include an optical disk drive 530 that reads from and writes to a removable optical disk 531 such as other (magnetic) optical media, a hard disk drive 527, a magnetic disk drive 528, and a (magnetic) optical disk. The drive 530 includes a hard disk drive interface 532, a magnetic disk drive interface 533, and a (magnetic) optical disk drive interface 534. Via the system bus 523. The drives and their associated storage media are machine readable instructions, data structures, program modules and other data non-volatile for the personal computer 520. One example of the environment described herein employs a hard disk, a removable magnetic disk 529, and a removable optical disk 531, but those skilled in the art will recognize magnetic cassettes, flash memory cards, digital video disks, Bernoulli. Other types of storage media such as cartridges, random access memory (RAM), read only memory (ROM), etc. can be used instead of or in addition to the previously introduced storage devices Let's admit that it is possible.

  For example, a number of program modules, such as operating system 535, one or more application programs 536, other program modules 537, and / or program data 538, may be stored on hard disk 527, magnetic disk 529, ( It can be stored on a magnetic) optical disk 531, ROM 524 or RAM 525. 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 (not shown) such as a microphone, joystick, game pad, satellite dish, scanner, etc. may also be included. Often, these and other input devices are connected to the processing unit 521 via a serial port interface 546 that is coupled to the system bus. However, the input device can also be connected by other interfaces such as a parallel port, a game port or a universal serial bus (USB). A monitor 547 or other display device can also be connected to the system bus 523 via an interface, such as a video adapter 548, for example. In addition to the monitor 547, the personal computer 520 can also include other peripheral output devices (not shown), such as speakers and printers, for example.

  The personal computer 520 can also operate in a network environment that defines logical connections to one or more remote computers, such as a remote computer 549. The remote computer 549 can be another personal computer, server, router, network PC, peer device or other common network node, and is further described above in connection with the personal computer 520. Many or all of the elements can be included. The logical connections shown in FIG. 5 include a local area network (LAN) 551 and a wide area network (WAN) 522, an intranet and the Internet.

  When used in a LAN, the personal computer 520 can be connected to the LAN 551 through a network interface adapter (ie, “NIC”) 553. When used in a WAN such as the Internet, the personal computer 520 may include a modem 554 or other means of establishing communications over the wide area network 552. The modem 554 may be internal or external and can be connected to the system bus 523 via the serial port interface 546. In a network environment, at least some of the program modules previously described in connection with the personal computer 520 can be stored in a remote memory storage device. The network connections shown are exemplary and other means of establishing a communications link between the computers can be used.

  FIG. 7A illustrates a display device 600 implemented in accordance with one embodiment of the present invention. Display device 600 is suitable for use in, for example, a portable computer or other system where a flat panel display is desired. The display device 600 can be realized as an LCD display. In one embodiment, the display and control logic of known computer 100 is replaced with the display device 600 and display control logic of the present invention, eg, a routine, to represent horizontal RGB striping and different portions of the image to a portable computer. The pixel subcomponent used in

  As shown in the figure, the display device 600 includes 16 columns of pixel elements C1 to C16 and 12 rows of pixel elements R1 to R12, and is a display having 16 × 12 pixels. As with most computer monitors, the display 600 is arranged so that its horizontal size is larger than its vertical size. Although the display 700 is limited to 16 × 12 pixels for purposes of illustration in this patent, a monitor of the type shown in FIG. 7A can have any number of vertical and horizontal pixel elements, for example, 640 × 840. 800 × 600, 1024 × 768, and 1280 × 1024 horizontal to vertical pixel ratios, as well as displays having ratios that yield a square display are possible.

  Each pixel element of display 600 includes three subcomponents, a red pixel subcomponent 602, a green pixel subcomponent 604, and a blue pixel subcomponent 606. In the embodiment of FIG. 7A, each pixel sub-component 602, 604, 606 has a height equal to or approximately equal to 1/3 of the pixel height and a width equal to or approximately equal to the pixel width.

  In the monitor 600, the RGB pixel subcomponents are arranged to form a horizontal stripe. This is the reverse of the vertical stripe arrangement used for the monitor 200 described above. In particular, monitor 600 may be used, for example, in graphics applications where it is desirable for the vertical resolution to be higher than the horizontal resolution in the application.

  FIG. 7B shows the upper left portion of the display 600 in more detail. In FIG. 7B, the horizontal RGB striping pattern can be clearly seen and the letters R, G and B are used to indicate the corresponding color pixel sub-components.

  FIG. 7C shows another display device 700 implemented in accordance with the present invention. FIG. 7C illustrates the use of vertical RGB striping in a display device that has more vertical pixel elements than horizontal pixel elements, eg, an LCD display. Although a 12 × 16 display is shown, it will be appreciated that the display 700 can be implemented with any number of pixel columns / rows and also includes a column / row ratio that results in a square display.

  Display device 700 is particularly suitable when a portrait type display of horizontally flowing text is desired. As with the monitor of FIG. 2A, each pixel element consists of three sub-pixel components, namely the R, G, and B pixel sub-components.

  Display 7A is desirable for certain graphics applications, but to produce a high quality character, an accurate representation of the character stem, a relatively long and thin vertical portion of the character, is much more than a serif representation. Is important to. Vertical striping has the particular advantage that when used in accordance with the present invention, the stem can be adjusted by one third of the pixel width at a time. Thus, by using a display device such as device 200 or 700 with a vertical striping arrangement in conjunction with the display method of the present invention, a higher quality than known horizontal striping arrangements where the stem adjustment is limited to one pixel at a time. You can get text.

  Another advantage of vertical striping is that the character spacing can be adjusted with a step size smaller than the pixel size, eg, 1/3 step of the pixel size. Character spacing is an important text property for legibility. Therefore, by using vertical striping, text spacing can be improved and stem weights can be refined.

  FIG. 8 illustrates various elements, eg, routines, included in the memory of the computer system of FIG. 5 that are used in rendering a text image on the display of the computer system according to the present invention.

  As shown, application routine 536 can be, for example, a word processor application and includes a text output subcomponent 801. The text output subcomponent 801 is responsible for outputting text information to the operating system 535 for rendering on the display device 547 as represented by arrow 813. The text information includes, for example, information for identifying a character to be rendered, a font used during rendering, and a point size at which the character is rendered.

  Operating system 535 includes various components responsible for controlling the display of text on display device 547. These components include display information 815, display adapter 814, and graphics display interface 802. Display information 815 includes, for example, information regarding scaling applied during rendering and / or foreground / background color information. The display adapter receives the bitmap image from the graphics display interface 802, generates a video signal, and supplies it to the video adapter 548 for optical display on the display 547. Arrow 815 represents the passage of the bitmap image from the graphics display interface 802 to the display adapter 814.

  The graphics display interface 802 includes routines for processing graphics as well as text. Element 804 is a type rasterizer used to process text. The type rasterizer is responsible for processing text information obtained from the application 536 and generating a bitmap representation therefrom. Type rasterizer 804 includes character data 806 and rendering and rasterization routines 807.

  Character data 806 includes, for example, vector graphics, lines, points, and curves to provide a high resolution digital representation of one or more sets of characters.

  As shown in FIG. 3, processing a text character 302 and generating its high resolution digital representation, such as data 806, can be stored in memory and used during text generation. It is known. Accordingly, the generation 304 and storage 306 of the data 806 will not be discussed in detail here.

The rendering and rasterization routine 807 includes a scan conversion subroutine 812, and can also include a scaling subroutine 808, a hinting subroutine 810, and a color compensation routine 813. While it is common to perform scan conversion operations and render text images, the routines and subroutines of the present invention utilize or treat the RGB pixel subcomponent of the screen as a separate luminosity entity and render the rendered image. It differs from the known subroutine in that it can be used to represent different parts. The color compensation subroutine 813 may result from performing color compensation adjustments on the bitmap image created by the scan conversion subroutine 812 and treating each of the three color subcomponents of the pixel as a separate luminosity element. It plays a role in compensating for no color edge effects. The operations performed by each of the subroutines 808, 810, 812 and 813 of the present invention will be described in more detail.
B. Scan Conversion Operation Scan conversion involves the conversion of a geometric shape representing a scaled character into a bitmap image. Conventional scan conversion operations treat pixels as individual units that can map corresponding portions of the scaled image. Thus, in a conventional scan conversion operation, the same portion of the image is used to determine the luminosity value and use it with each of the RGB pixel subcomponents of the pixel element to which a portion of the scaled image is mapped. FIG. 2C is an example of a known scan conversion process that involves sampling an image represented as a bitmap and generating a light intensity value from the sample value.

  According to the present invention, the RGB pixel subcomponent of a pixel is treated as an independent luminous intensity element. Thus, each pixel subcomponent can be treated as a separate luminosity component, to which a separate portion of the scaled image can be mapped. Thus, the present invention allows different parts of the scaled image to be mapped to different pixel sub-components and can obtain a higher resolution than is possible with known scan conversion techniques. That is, in various embodiments, different portions of the scaled image are used to independently determine the light intensity value to use with each pixel subcomponent.

  FIG. 6 shows an example of scan conversion performed in accordance with one embodiment of the present invention. In the illustrated embodiment, red, green associated with corresponding portions 632, 633, 634 of the resulting bitmap image 630 using separate spatially displaced image samples 622, 623, 624 of the image represented by the grid 620. And generate blue intensity values. Sampling the image data and mapping the separate image samples 622, 623, 624 to the red, green, blue pixel subcomponents associated with portions 632, 633, 634 as shown in FIG. Represents an example of an act or act corresponding to the step of mapping to individual pixel subcomponents. In the example of FIG. 6, the image samples for red and blue are spatially displaced from the green sample by distances of -1/3 and +1/3 of a pixel width, respectively. In this way, the displacement problem that occurs with the known sampling / image representation method shown in FIG. 2C is avoided.

  In the example shown in the figure, white is used to indicate a pixel subcomponent that is “turned on” in a bitmap image generated by a scan conversion operation. Pixel subcomponents that are not white are in the “off” state.

  For black text, “on” implies that the intensity value associated with the pixel subcomponent is controlled to prevent the pixel subcomponent from outputting light. Assuming a white background pixel, a sub-component that is not “on” will be assigned an intensity value that outputs the maximum light output.

  When using foreground and background colors, “on” means that if all three pixel subcomponents are used to generate the foreground color, a value that generates the specified foreground color is assigned to the pixel subcomponent. A pixel subcomponent that is not “ON” is assigned a value that generates a designated background color if a background color is to be generated using all three pixel subcomponents.

  A first technique for determining whether to turn on a pixel subcomponent during scaling is represented by the center of the scaled image segment represented by a portion of the scaling grid and mapped to the pixel subcomponent. It is to determine whether it is inside the scaled representation of the image. For example, in FIG. 12A, pixel subcomponents C1, R5 are turned on when the center of grid segment 1020 is inside image 1004 (shown in FIG. 11A). Another technique is to determine whether 50% or more of the scaled image segment mapping to the pixel subcomponent is occupied by the image to be displayed. If so, turn on the pixel subcomponent. For example, if the scaled image segment represented by grid segment 1202 is occupied by at least 50% image 1004, turn on the corresponding pixel subcomponent C1, R5. The examples of FIGS. 12A, 12B, 13 and 14 discussed below employ a first technique for determining when to turn on a pixel subcomponent.

  FIG. 12A shows a scan conversion operation performed on the hint image 1014 for display on the display device of horizontal striping. Examples of scaling and hinting operations that can result in image 1014 are described in detail below with reference to FIGS. 10A and 11A. However, to briefly describe these exemplary scaling and hinting operations, FIG. 10A shows that for a high resolution representation of the letter i (1002), the character on a horizontal striping monitor such as that shown in FIG. The scaling operation is executed in anticipation of the display. Here, in this example, scaling in the horizontal (X) direction is applied at a rate of x1, while scaling in the vertical (Y) direction is applied at a rate of x3. This results in a scaled character 1004 that is three times longer than the original character 1002 but the same width. Other quantities are possible for scaling.

  Hinting, when used in conjunction with the scan conversion operation of the present invention, can include alignment of the scaled character, eg, character 1004 in FIG. 11A within a grid 1102 that is used as part of a subsequent scan conversion operation. Alignment. This can also include distorting the image contour to better fit the image to the shape of the grid. This grid can be determined as a function of the physical size of the pixel elements of the display device. The hinting operation of FIG. 11A produces a hinted image 1014.

  The scan conversion operation of FIG. 12A produces a bitmap image 1204. Note how each pixel sub-component of bitmap image sequence C1-C4 is determined from a different segment of the corresponding column of scaled hinted image 1014. Also, here, how the bitmap image 1204 is composed of 2/3 pixel height bases aligned along the green / blue pixel boundary and 1/3 pixel height dots. Please be careful. Known text imaging techniques will result in a less accurate image with one full pixel height base and one full pixel size dot.

  FIG. 12B shows the scan conversion operation performed on the hinted image 1018 for display on a display device with vertical striping. Examples of scaling and hinting operations that can result in image 1018 are described below with reference to FIGS. 10B and 11B. However, to briefly describe these exemplary scaling and hinting operations, FIG. 10B shows a high-resolution representation of the letter i (1002) on a vertical striping monitor such as that shown in FIGS. 2A and 7C. The scaling operation is executed in anticipation of displaying the character. Here, in the first time, 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 x1. This results in a scaled character 1008, which is the same length as the original character 1002, but three times wider. Other quantities are possible for scaling.

  FIG. 11B shows a hinting operation that results in the alignment of the scaled character 1008 within the grid 1104 for use as part of a subsequent scan conversion operation. This can also include distorting the image contour to better fit the image to the shape of the grid. The hinting operation of FIG. 11B results in a hinted image 1018.

  A bitmap image 1203 is obtained by the scan conversion operation. Note how each pixel subcomponent in the rows R1-R8 of the bitmap image is determined from a different segment in the corresponding row of the scaling hint image 1018. Also note how the bitmap image 1203 is composed of 2/3 pixel wide stems with left edges aligned along the red / green pixel boundary. Also note that pixels that are 2/3 of a pixel in width are used. With known text imaging techniques, the resulting image will be less accurate and will have stems with a maximum pixel width and dots with a size of one pixel.

  FIG. 13 shows in more detail the scan conversion process performed on the first column of the image 1014 shown in FIG. 12A. In the scan conversion process shown, one segment of the image 1014 is used to control the light intensity value associated with each pixel subcomponent. This causes each pixel subcomponent to be controlled by the same size portion of the scaled image 1014.

  It is also possible to apply weighting during the scan conversion operation. When applying weighting, use different sized regions of the scaled image to turn individual pixel subcomponents on, off, or intermediate values (as in gray scaling) ).

  As mentioned above, the human eye perceives different rates of light intensity from different color light sources. Green contributes about 60% to the perceived brightness of white pixels obtained by setting the red, green and blue pixel subcomponents to their maximum light intensity output, red contributes about 30%, and blue contributes about 10%. Contribute.

  According to one embodiment of the present invention, when weighting is used during scan conversion, the luminosity of the green pixel subcomponent is determined using 60% of the scaled image area that maps to the pixel, and the scaled image area that maps to the same pixel. A separate 30% of the red pixel subcomponent is used to determine the intensity of the red pixel subcomponent, and a separate 10% of the scaled image area that maps to the same pixel is used to determine the intensity of the blue pixel subcomponent.

  In one particular embodiment of the present invention, during the scaling operation, the image is scaled in a direction perpendicular to striping at a rate that is 10 times the rate of scaling in the direction of striping. This simplifies the weighted scan conversion operation. After hinting, the scaled image is then processed during scan conversion using, for example, a weighted scan conversion operation of the type described above.

Figure 10A shows the ratio a and image 1002 scaled first magnification in the horizontal direction 3 in the vertical direction. In contrast, FIG. 14 shows the execution of a weighted transform operation on the first column 1400 of scaling hint images, with image 1002 scaled 10 times vertically and 1 time horizontally. In FIG. 14, the portion of the hint image corresponding to a single pixel consists of 10 segments. In accordance with the weighted scaling technique described above, the first set of three segments of each pixel area of the scaled image is used to determine the luminosity value of the red pixel subcomponent corresponding to one pixel in the bitmap image 1402. The next set of six segments in each pixel area of the scaled image 1400 is used to determine the luminosity value of the green pixel subcomponent corresponding to the same pixel in the bitmap image 1402. Thus, the last segment of each pixel area of the scaled image 1400 is left for use in determining the light intensity value of the blue pixel subcomponent.

  As shown in FIG. 14, this process turns on the blue pixel subcomponent of column 1, row 4 and the red pixel subcomponent of column 1, row 5 of the bitmap image 1402, and the remaining pixel subcomponents of column 1. The component is “off”.

In general, the scan conversion process of the present invention has been described with respect to turning pixel subcomponents “on” or “off”.
Various embodiments of the present invention, particularly those suitable for use with, for example, graphics images, involve the use of gray scale technology. In such an embodiment, as in the previous embodiment, the scan conversion operation involves independently mapping a portion of the scaling hint image to the corresponding pixel subcomponent to form a bitmap image. . However, in the gray scale embodiment, the intensity value assigned to the pixel subcomponent is determined as a function of the portion of the scaled image that maps to the pixel subcomponent occupied by the displayed scaled image. For example, an intensity value between 0 and 255 can be assigned to the pixel subcomponent, where 0 is effectively off and 255 is the maximum intensity, the image that the segment of the scaled image (grid segment) displays. The intensity value of 123 would be assigned to the pixel subcomponent as a result of mapping the scaled image segment to the corresponding pixel subcomponent. In accordance with the present invention, pixel subcomponents adjacent to the same pixel will have intensity values that are independently determined as a function of another portion of the scaled image, eg, a segment.
C. Exemplary Rendering Routine The scan conversion operation of the present invention can be used with the rendering / rasterization routine 807 of FIG. 9 to render text for display in accordance with one embodiment of the present invention. As shown, the routine 807 begins at step 902, where the routine executes in response to receiving text information from the application 536, eg, under the control of the operating system 535. In step 904, the text rendering / rasterization routine 807 receives input. This input includes text, font, and point size information 905, which are obtained from application 536. In addition, this input includes scaling information and / or foreground / background color information, and pixel size information 815, which are obtained from monitor settings stored in memory by the operating system, for example. The input also includes data 806, which includes a high resolution representation, eg, in the form of lines, points, and / or curves of text characters to be displayed.

  With this input received at step 904, operation proceeds to step 910, where a scaling operation may also be performed using the scaling subroutine 808. Non-square scaling can be performed as a function of the direction and / or number of pixel subcomponents contained within each pixel element. In particular, high resolution character data 806, for example, line and point representations of characters to be displayed specified by received text and font information, scale in a direction perpendicular to striping at a greater rate than in the direction of striping. . This allows subsequent image processing operations to take advantage of the higher resolution that can be achieved by using individual pixel subcomponents as independent luminous intensity sources according to the present invention.

  Details of an exemplary scaling operation that can be used with the scan conversion operation of the present invention are described in US Patent entitled “Method and Apparatus for Displaying Images such as Text”. Application 09 / 168,012 is disclosed, for example, in FIGS. 10A and 10B and the accompanying text. This application is a continuation of US patent application 09 / 168,012 and is hereby incorporated by reference.

  Referring again to FIG. 9, the operation then proceeds to step 912, where hinting of the scaled image can also be performed, for example, by executing a hinting subroutine 810. The term “grid-fitting” is sometimes used to describe this hinting process.

  Hinting includes alignment of scaled characters, eg, characters 1004, 1008, in grids 1102, 1104 that are used as part of subsequent scan conversion operations. This can also include distorting the image contour to better fit the image to the shape of the grid. This grid can be determined as a function of the physical size of the pixel elements of the display device. Details of an exemplary hinting operation that can be used with the scan conversion operation of the present invention are described in US patent application 09 entitled “Method and Apparatus for Displaying Images such as Text”. / 168,012 is disclosed in, for example, FIGS. 11A and 11B and the accompanying text. The operation then proceeds to step 914, where a scan conversion operation such as that disclosed herein is performed in accordance with the present invention, for example, by executing a scan conversion subroutine 812.

  Once the bitmap representation of the text to be displayed has occurred in step 814 of FIG. 9, it is output to the display adapter or further processed to perform color processing operations and / or color adjustments to improve image quality. It is also possible. Details of exemplary color processing operations and color adjustments that can be used with the scan conversion operation of the present invention are disclosed in US patent application Ser. No. 09 / 168,012.

  This processed bitmap 918 is output to the display adapter 814 and the routine 807 operation is halted until additional data / images are received for processing.

FIG. 15 shows a high resolution representation of character n to render for superimposition on a grid representing a 12 × 12 pixel array of horizontal striping.
FIG. 16 shows how to render the character n shown in FIG. 15 using conventional display techniques and full size pixel elements each containing three pixel subcomponents. Note that due to the full size pixel limitation, shape transitions occur relatively abruptly in the character ridge, resulting in aliasing and a relatively flat top.

  FIG. 17 shows how the rendering of the letter n can be improved in accordance with the present invention by using a 2/3 base of pixel height. Two pixel subcomponents are used to form the base. This is in contrast to using all three pixel subcomponents in row 10, columns 1-4 and 8-10. Also note how to improve the letter ridge. The width of the ridge is the maximum pixel height, but each horizontal maximum height pixel element is shifted in the vertical direction by 1/3 pixel height, so that it is much more accurate and smooth than the ridge shown in FIG. Ridge can be obtained.

FIG. 18 shows how the thickness of the ridge of the letter n can be reduced from a 1 pixel thickness to a 2/3 pixel thickness according to the present invention.
FIG. 19 shows how the base of the letter n can be reduced to a minimum thickness of 1/3 of a pixel according to the present invention. It also shows how the letter n ridge can be reduced to 1/3 the thickness of the pixel.

FIG. 20 illustrates how the letter n can be displayed according to the present invention, with the base and ridge having a thickness of 1/3 of the pixel.
One example of a display device capable of performing the scan conversion operation of the present invention is shown in FIG. 4, which depicts a computerized electronic book device 400. As shown in FIG. 4, the electronic book 400 comprises first and second display screens 402 and 404 for displaying one book odd-numbered page and even-numbered page, respectively. For example, a display of the type shown in FIG. 7C can be used as the displays 402 and 404 of the electronic book 400 of FIG. The electronic book 400 further includes input devices such as a keypad or keyboard 408 and a data storage device such as a CD disk drive 407. By providing the hinge 406, the electronic book 400 can be protected when it is not in use by folding it. Similarly, an internal battery can be used to power the electronic book 400. Similarly, other portable computer embodiments of the present invention can be powered by a battery.

  Although the present invention has been described generally in terms of text rendering, the present invention can also be applied to graphics to reduce aliasing and be obtained using a striped display, such as a conventional color LCD display. It will be appreciated that the effective resolution can be improved. In addition, it will be appreciated that many of the techniques of the present invention can also be used to process bitmap images, eg, scanned images, and prepare them for display.

  In view of the description of the invention contained herein, many additional embodiments and modifications to the embodiments of the invention discussed above will be apparent to those skilled in the art. It will be understood that such embodiments do not depart from the invention and fall within the scope of the invention.

  It is a figure of a well-known portable computer.   FIG. 2A is a diagram of a known LCD screen. 2B is a diagram showing a part of the known screen shown in FIG. 2A in more detail than the diagram of FIG. 2A. FIG. 2C is a diagram illustrating an image sampling operation performed in a known system.   FIG. 4 illustrates known steps performed when character information is prepared and stored for use in subsequent text generation and display.   FIG. 2 shows an electronic book with a flat panel display arranged in a portrait orientation according to one embodiment of the present invention.   FIG. 2 illustrates a computer system implemented in accordance with the present invention.   FIG. 6 illustrates image sampling performed according to an example embodiment of the present invention.   FIG. 7A is a diagram illustrating a color flat panel display screen implemented in accordance with the present invention. FIG. 7B is a diagram showing a part of the display screen of FIG. 7A. FIG. 7C is a diagram illustrating a display screen implemented in accordance with another embodiment of the present invention.   FIG. 6 illustrates various elements, eg, routines, included in the memory of the computer system of FIG. 5 that are used to render a text image on a display of the computer system.   FIG. 3 illustrates a method for rendering and displaying text according to one embodiment of the present invention.   10A and 10B are diagrams illustrating scaling operations performed in accordance with various example embodiments of the present invention.   11A and 11B are diagrams illustrating hinting operations performed in accordance with various example embodiments of the present invention.   12A and 12B are diagrams illustrating scan conversion operations performed in accordance with various example embodiments of the present invention.   It is a figure which shows the scan conversion process applied to the 1st row | line | column of the image data shown to FIG. 12A in detail.   FIG. 6 is a diagram illustrating a weighted scan conversion operation performed according to an embodiment of the present invention.   It is a figure which shows the high-resolution expression of the character displayed on the field of a pixel.   It is a figure which shows how the character of FIG. 15 is shown when a well-known technique is used.   FIG. 16 illustrates different methods of illustrating the character shown in FIG. 15 in accordance with various text rendering techniques of the present invention.   FIG. 16 illustrates different methods of illustrating the character shown in FIG. 15 in accordance with various text rendering techniques of the present invention.   FIG. 16 illustrates different methods of illustrating the character shown in FIG. 15 in accordance with various text rendering techniques of the present invention.   FIG. 16 illustrates different methods of illustrating the character shown in FIG. 15 in accordance with various text rendering techniques of the present invention.

Claims (13)

Processing unit and the image comprises a display device for displaying, the display device includes a plurality of pixels, in a computer system including at least three pixel sub-components of each pixel are each different color, the resolution of the scale in which these images The pixel subcomponents of the plurality of pixels are arranged to form a stripe of pixel subcomponents of the same color in the display device, the method comprising:
Scaling the image in a direction perpendicular to the stripe with a greater magnification in a direction parallel to the stripe;
Mapping a sample of information representing a scaled image to the pixel subcomponent of a pixel, the scaled image having an image region portion corresponding to each of the plurality of pixels of the display device , said segments the image area portion has at least three segments correspond to the at least three pixel sub-components of each said pixel, for each pixel subcomponent of the pixel, which corresponds to the respective pixel sub-component The samples in are mapped, steps,
Generating a light intensity value for each pixel subcomponent based on the sample mapped to each pixel subcomponent;
Displaying an image on the display device by controlling each of the pixel subcomponents using the light intensity value;
Including methods.
Said step of generating a luminous intensity value for the pixel sub-components, and the segments that are mapped to each said pixel sub-component, based on the relative position between the image of the sample described above scaling in the segment, each of said images The method of claim 1, comprising selecting an on or off intensity value for the subcomponent.
PreviousThe at least three pixel subcomponents include a first pixel subcomponent, a second pixel subcomponent, and a third pixel subcomponent.,
  The at least three segmentsIs, First segment mapped to the first pixel subcomponentWhen, A second segment mapped to the second pixel subcomponentWhenA third segment mapped to the third pixel sub-componentWhenincluding,Claim 1Method.
A computer-readable storage medium storing executable instructions , wherein when the executable instructions are executed by a computer, the computer executes a method for improving the resolution of an image displayed on a display device, The display device has a plurality of pixels for displaying an image, and each pixel includes at least three pixel subcomponents of different colors, and the pixel subcomponents of the plurality of pixels have the same color in the display device It is arranged to form a stripe of pixels subcomponents, the method comprising:
Scaling the image in a direction perpendicular to the stripe with a greater magnification in a direction parallel to the stripe;
Mapping a sample of information representing a scaled image to the pixel subcomponent of a pixel, the scaled image having an image region portion corresponding to each of the plurality of pixels of the display device , said segments the image area portion has at least three segments correspond to the at least three pixel sub-components of each said pixel, for each pixel subcomponent of the pixel, which corresponds to the respective pixel sub-component The samples in are mapped, steps,
Generating for each said pixel subcomponent a luminous intensity value based on said sample mapped thereto;
Displaying an image on the display device by controlling each of the pixel subcomponents using the light intensity value;
A computer readable storage medium comprising:
Wherein the step of generating a luminous intensity value for the pixel sub-component based on the relative position of said segments that are mapped to each said pixel sub-component, a sample of an image obtained by the scaling in the segment, each of said images 5. The computer readable storage medium of claim 4 , comprising selecting an on or off intensity value for the subcomponent.
PreviousThe at least three pixel subcomponents are a first pixel subcomponent, a secondPixelSubcomponent and thirdPixelIncluding subcomponents,
  The at least three segmentsIs, First segment mapped to the first pixel subcomponentWhen, A second segment mapped to the second pixel subcomponentWhenA third segment mapped to the third pixel sub-componentWhen5. The computer readable medium of claim 4, comprising:MemoryMedium.
A computer system comprising a processing unit, a storage device and a display device capable of displaying an image, the display device comprising a plurality of pixels, each pixel comprising at least three pixel subcomponents, each of a different color; a computer program stored in the storage device, a method for improving the resolution of the scale in which these images include executable instructions to allow the said processing units execute, the pixel sub-component of the plurality of pixels , Arranged to form a stripe of pixel subcomponents of the same color in the display device,
The method
Scaling the image in a direction perpendicular to the stripe with a greater magnification in a direction parallel to the stripe;
Mapping a sample of information representing a scaled image to the pixel subcomponent of a pixel, the scaled image having an image region portion corresponding to each of the plurality of pixels of the display device , said segments the image area portion has at least three segments correspond to the at least three pixel sub-components of each said pixel, for each pixel subcomponent of the pixel, which corresponds to the respective pixel sub-component The mapping step wherein the samples in are mapped;
Generating for each said pixel subcomponent a luminous intensity value based on said sample mapped thereto;
Displaying an image on the display device by controlling each of the pixel subcomponents using the light intensity value;
Including computer systems.
The computer system according to claim 7 , wherein the display device includes a liquid crystal display having the plurality of pixels.
9. The computer of claim 8 , wherein the at least three pixel subcomponents of each of the plurality of pixels include a red pixel subcomponent, a green pixel subcomponent, and a blue pixel subcomponent, each controllable separately. ·system.
The computer system of claim 8 , wherein at least a portion of the image includes a text character, and the text character is displayed on the display device by the step of displaying the image.
The pixel subcomponents of the plurality of pixels are arranged to form a stripe of pixel subcomponents of the same color in the display device, and the text character is an integer of pixel dimension values in a direction perpendicular to the stripe The computer system of claim 10 , comprising a portion having a dimension having a non-double value in a direction perpendicular to the stripe.
The computer system of claim 11 , wherein the portion of the text character is a stem of the text character, and the width of the stem is not an integer multiple of the width of the pixel.
PreviousThe at least three pixel subcomponents include a first pixel subcomponent, a second pixel subcomponent, and a third pixel subcomponent;
  The at least three segmentsIs, First segment mapped to the first pixel subcomponentWhen, A second segment mapped to the second pixel subcomponentWhenA third segment mapped to the third pixel sub-componentWhenincluding,Claim 7Computer system.

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