Method and apparatus for displaying images such as text

• US 6,188,385 B1
• Filed: 10/07/1998
• Issued: 02/13/2001
• Est. Priority Date: 10/07/1998
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Hitchcock, Gregory C., Duggan, Michael, Hill, William, Whitted, J. Turner, Keely, Leroy B. Jr.
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Tran, Henry N.
• Application Number:
  US09/168,012
• Time in Patent Office: 860 Days
• Field of Search: 345/152, 345/55, 345/63, 345/72, 345/88-90, 345/147, 345/149, 345/136, 345/901, 345/905, 345/947, 345/137, 345/138, 345/468, 345/471, 345/472
• US Class Current: 345/614
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 2340/0414 Vertical resolution change
• CPC Class Codes: G09G 2340/0421 Horizontal resolution change
• CPC Class Codes: G09G 2340/0457 Improvement of perceived resolution by subpixel rendering
• CPC Class Codes: G09G 3/20 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
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/24 Generation of individual character patterns
• CPC Class Codes: G09G 5/28 for enhancement of character form, e.g. smoothing

Abstract

Methods and apparatus for utilizing pixel sub-components which form a pixel element of an LCD display, e.g., as separate luminous intensity elements, are described. Each pixel of a color LCD display is comprised of three non-overlapping red, green and blue rectangular pixel sub-elements or sub-components. The invention takes advantage of the ability to control individual RGB pixel sub-elements to effectively increase a screen'"'"'s resolution in the dimension perpendicular to the dimension in which the screen is striped, e.g., the RGB pixel sub-elements are arranged lengthwise. In order to utilize the effective resolution which can be obtained by treating RGB pixel sub-components separately, scaling or super sampling of digital representations of fonts is performed in one dimension at a rate that is greater than the scaling or sampling performed in the other dimension. In some embodiments where weighting is used in determining RGB pixel values, e.g., during scan conversion, the super sampling is a function of the weighting. During a scan conversion operation, RGB pixel sub-component values are independently determined from different portions of a scaled image. The scan conversion process may involve use of different weights for each color component. Processing to compensate for color distortions, e.g., color fringing, introduced by treating each pixel sub-component as an independent element is described. For horizontally flowing text applications, screens with vertical as opposed to horizontal striping are preferred.

Claims

1. In a computer system including a processing unit and a display device for displaying an image, the display device having a plurality of pixels, each including a plurality of pixel sub-components each of a different color, a method of improving resolution of the displayed image comprising the steps for:

mapping samples of information representing an image to individual pixel sub-components of a pixel as opposed to mapping each of the samples to an entire pixel, each pixel sub-component having mapped thereto at least one spatially different sample;

generating a separate luminous intensity value for each pixel sub-component as opposed to each full pixel, the separate luminous intensity value for each sub-component being based on the at least one spatially different sample mapped thereto; and

displaying the image using the separate luminous intensity values of each sub-component, resulting in each of the pixel sub-components of the pixel, rather than entire pixels, representing displayed portions of the image.

2. A method as defined in claim 1, wherein the pixel sub-components of the plurality of pixels are arranged to form vertical stripes of same-colored pixel sub-components on the display device, and wherein the method is further comprised of the step for scaling the information representing the image in the direction perpendicular to the stripes by a factor greater than in the direction parallel to the stripes prior to the step for mapping the samples.

3. A method as defined in claim 1 or 2, wherein the step for mapping the samples is comprised of an act wherein each of the pixel sub-components of the pixel has mapped thereto one and only one of the samples.

4. A method as defined in claim 1 or 2, wherein the step for mapping the samples is comprised of an act wherein at least one of the pixel sub-components of the pixel has mapped thereto two or more of the samples.

5. A method as defined in claim 4, wherein the step for mapping the samples is comprised of an act wherein different numbers of samples are mapped to each of the pixel sub-components of the pixel.

6. A method as defined in claim 1 or 2, wherein the step for mapping the samples is comprised of an act wherein the information representing the image includes an outline of the image and has associated therewith a foreground color and a background color.

7. A method as defined in claim 6, wherein the step for generating a luminous intensity value for each pixel sub-component comprises a step for selecting an on or off luminous intensity value based on the relative position of the image and the at least one spatially different sample mapped to each pixel sub-component.

8. In a computer system including a processing unit and a display device for displaying an image, the display device having a plurality of pixels, each including at least three pixel sub-components each of a different color, a method for improving resolution of the displayed image comprising the acts of:

sampling information representing an image so at to obtain a plurality of samples;

mapping a first sample to a first pixel sub-component of a pixel of the display device;

mapping a second sample to a second pixel sub-component that is adjacent to the first pixel sub-component, the second pixel sub-component being one of i) a sub-component of the same pixel as the first pixel sub-component and ii) a sub-component of an adjacent pixel;

generating, for each of the first and second pixel sub-components, a separate luminous intensity value based on the samples mapped thereto; and

displaying at least some portions of the image using a number of pixel sub-components different from the number of pixel sub-components in a full pixel or an integer multiple thereof, by separately controlling each of the first and second pixel sub-components using the separate luminous intensity values.

9. A method as defined in claim 8, wherein the pixel sub-components of the plurality of pixels are arranged to form vertical stripes of same-colored pixel sub-components on the display device, and wherein the act of displaying the image results in a text character that has a portion with a dimension, in the direction perpendicular to the stripes, having a value that is not an integer multiple of the value of the dimension of the pixels in the direction perpendicular to the stripes.

10. A method as defined in claim 9, wherein the portion of the text character is a stem of the text character, and wherein the dimension of the stem is not an integer multiple of the width of the pixels.

11. A method as defined in claim 9, further comprising the act of scaling the information representing the image in the direction perpendicular to the stripes by a factor greater than in the direction parallel to the stripes prior to the act of sampling the information.

12. A method as defined in claim 8 or 9, wherein the display device comprises a liquid crystal display, and wherein the first, second, and third pixel sub-components have a red, green, and blue color, respectively.

13. A method as defined in claim 8 or 9, further comprising the act of performing a color processing operation on the information representing the image, the color processing operation compensating for color distortion that has been introduced to the information as the samples were mapped to the first, second, and third pixel sub-components.

14. In a computer system including a processing unit and a display device for displaying an image, the display device having a plurality of pixels, each including a plurality of pixel sub-components each of a different color, a computer program product for implementing a method of improving resolution of the displayed image, the computer program product comprising:

a computer-readable medium carrying executable instructions for performing the method; and

wherein the method is comprised of the steps for;

mapping samples of information representing an image to individual pixel sub-components of a pixel as opposed to mapping each of the samples to an entire pixel, each pixel sub-component having mapped thereto at least one spatially different sample;

generating a separate luminous intensity value for each pixel sub-component as opposed to each full pixel the separate luminous intensity value for each sub-component being based on the at least one spatially different sample. mapped thereto; and

displaying the image using the separate luminous intensity values of each sub-component, resulting in each of the pixel sub-components of the pixel, rather than entire pixels, representing displayed portions of the image.

15. A computer program product as defined in claim 14, wherein the pixel sub components of the plurality of pixels are arranged to form vertical stripes of same-colored pixel sub-components on the display device, and wherein the method is further comprised of the step for scaling the information representing the image in the direction perpendicular to the stripes by a factor greater than in the direction parallel to the stripes prior to the step for mapping the samples.

16. A computer program product as defined in claim 14 or 15, wherein the step for mapping the samples is comprised of an act wherein each of the pixel sub-components of the pixel has mapped thereto one and only one of the samples.

17. A computer program product as defined in claim 14 or 15, wherein the step for mapping the samples is comprised of an act wherein at least one of the pixel sub-components of the pixel has mapped thereto two or more of the samples.

18. A computer program product as defined in claim 17, herein the step for mapping the samples is comprised of an act wherein different numbers of samples are mapped to each of the pixel sub-components of the pixel.

19. A computer program product as defined in claim 14 or 15, wherein the step for mapping the samples is comprised of an act wherein the information representing the image includes an outline of the image and has associated therewith a foreground color and a background color.

20. A computer program product as defined in claim 19, wherein the step for generating a luminous intensity value for each pixel sub-component comprises a step for selecting an on or off luminous intensity value based on the relative position of the image and the at least one spatially different sample mapped to each pixel sub-component.

21. In a computer system including a processing unit and a display device for displaying an image, the display device having a plurality of pixels, each including a plurality of pixel sub-components each of a different color, a computer program product for implementing a method of improving resolution of the displayed image, the computer program product comprising:

a computer-readable medium carrying executable instructions for performing the method; and

wherein the method is comprised of the acts of;

sampling information representing an image so at to obtain a plurality of samples;

mapping a first sample to a first pixel sub-component of a pixel of the display device;

mapping a second sample to a second pixel sub-component that is adjacent to the first pixel sub-component, the second pixel sub-component being one of i) a sub-component of the same pixel as the first pixel sub-component and ii) a sub-component of an adjacent pixel;

generating, for each of the first and second pixel sub-components, at separate luminous intensity value based on the samples mapped thereto; and

displaying at least some portions of the image using a number of pixel sub-components different from the number of pixel sub-components in a full pixel or an integer multiple thereof by separately controlling each of the first and second pixel sub-components using the separate luminous intensity values.

22. A computer program product as defined in claim 21, wherein the pixel sub components of the plurality of pixels are arranged to form vertical stripes of same-colored pixel sub-components on the display device, and wherein the act of displaying the image results in a text character that has a portion with a dimension, in the direction perpendicular to the stripes, having a value that is not an integer multiple of the value of the dimension of the pixels in the direction perpendicular to the stripes.

23. A computer program product as defined in claim 22, wherein the portion of the text character is a stem of the text character, and wherein the dimension of the stem is not an integer multiple of the width of the pixels.

24. A computer program product as defined in claim 22, further comprising the act of scaling the information representing the image in the direction perpendicular to the stripes by a factor greater than in the direction parallel to the stripes prior to the act of sampling the information.

25. A computer program product as defined in claim 21 or 22, wherein the display device comprises a liquid crystal display, and wherein the first, second, and third pixel sub-components have a red, green, and blue color, respectively.

26. A computer program product as defined in claims 21 or 22, further comprising the act of performing a color processing operation on the information representing the image, the color processing operation compensating for color distortion that has been introduced to the information as the samples were mapped to the first, second, and third pixel sub-components.