Methods apparatus and data structures for enhancing the resolution of images to be rendered on patterned display devices

• US 6,393,145 B2
• Filed: 07/30/1999
• Issued: 05/21/2002
• Est. Priority Date: 01/12/1999
• Status: Expired due to Term

• Current Assignee: Kent State University, Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Platt, John C., Dresevic, Bodin, Betrisey, Claude, Mitchell, Donald P.
• Primary Examiner(s): Tran, Phuoc
• Assistant Examiner(s): Alavi, Amir
• Application Number:
  US09/364,365
• Publication Number:
  US 20010048764A1
• Time in Patent Office: 1,026 Days
• Field of Search: 382/162, 382/163, 382/164, 382/165, 382/166, 382/167, 345/418, 345/419, 345/426, 345/502, 358/515-526
• US Class Current: 382/162
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2340/0457 Improvement of perceived resolution by subpixel rendering
• CPC Class Codes: G09G 2340/10 Mixing of images, i.e. displayed pixel being the result of an operation, e.g. adding, on the corresponding input pixels
• CPC Class Codes: G09G 5/005 Adapting incoming signals to the display format of the display terminal
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04
• CPC Class Codes: G09G 5/024 using colour registers, e.g. to control background, foreground, surface filling G09G5/06 takes precedence
• CPC Class Codes: G09G 5/28 for enhancement of character form, e.g. smoothing

Abstract

Techniques for improving the resolution of images (either analog images, analytic images, or images having a higher resolution than that of a display device) to be rendered on patterned displays. In one aspect of the present invention, an overscaling or oversampling process may accept analytic character information, such as contours for example, and a scale factor or grid and overscale or oversample the analytic character information to produce an overscaled or oversampled image. The overscaled or oversampled image generated has a higher resolution than the display upon which the character is to be rendered. Displaced samples of the overscaled or oversampled image are then combined (or filtered). An analytic image, such as a line drawing for example, may be applied to the oversampling/overscaling process as was the case with the character analytic image. However, since the analytic image may have different units than that of the character analytic image, the scale factor applied may be different. Since an ultra resolution image is already “digitized”, that is, not merely mathematically expressed contours or lines between points, it may be applied directly to a process for combining displaced samples of the ultra-resolution image to generate another ultra-resolution image (or an image with sub-pixel information). The functionality of the overscaling/oversampling process and the processes for combining displaced samples may be combined into a single step analytic to digital sub-pixel resolution conversion process.

Claims

1. For use in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different colors per pixel, a method for improving spatial resolution of an image that is rendered by processing image information, the method comprising:

accepting digital scan lines of the image information representing a discrete values of an image, the scan lines including at least two color components, each said scan line comprising at least two samples per sub-pixel element, wherein each at least two samples correspond to one of the color components;

applying first filters to the digital scan lines to produce oversampled scan lines, wherein each oversampled scan line comprises at least two new samples for each sub-pixel component that are derived from the filtering of the sets of the samples;

for each of the sub-pixel elements in each of the oversampled scan lines, applying second filters to the new samples to generate a separate filtered color value associated with each sub-pixel element, the second filter from which the separate filtered color value for a given sub-pixel element is derived being spatially displaced from the second filters applied for other sub-pixel elements, such that each separate filtered color value is derived from spatially different samples of the oversampled scan lines;

mapping each separate filtered color value to the sub-pixel element associated therewith, such that each pixel element in a pixel has a different separate filtered color value mapped thereto; and

displaying the image by separately controlling each sub-pixel element using the separate filtered color value mapped thereto.

2. The method of claim 1 wherein each said scan line comprises exactly two samples per sub-pixel element.

3. The method of claim 1 wherein the second filters applied to the new samples comprise box filters, each of the box filters being centered at a spatial location corresponding to a sub-pixel element.

4. The method of claim 1 further comprising an act of gamma correcting the new samples.

18. A machine readable medium having stored instructions which, when executed by a machine used in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different colors per pixel, performs the method of claim 1.

19. A machine readable medium having stored instructions which, when executed by a machine used in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different colors per pixel, performs the method of claim 2.

24. The method of claim 1, wherein:

the device having a plurality of pixels comprises a liquid crystal display device;

the plurality of separately controllable sub-pixel elements per pixel include a red sub-pixel element, a green sub-pixel element, and a blue sub-pixel element; and

the second filter applied for each of the sub-pixel elements is a box filter centered about the particular sub-pixel element for which the box filter is applied and extends to an adjacent sub-pixel element on either side of said particular sub-pixel element.

5. For use in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements per pixel, a method for improving spatial resolution of an image that is rendered by processing image information including blend coefficients defining a blend between a foreground color and a background color, the method comprising:

accepting a digital scan line of the image information representing discrete samples of an image, the discrete samples of the scan line including samples of blend coefficients defining a blend between the foreground color and the background color;

applying first filters to the digital scan line to produce an oversampled scan line for the samples of blend coefficients, wherein the oversampled scan line comprises at least two new samples for each sub-pixel element;

for each of the sub-pixel elements, applying a second filter to a set of at least two of the new samples of the blend coefficients to generate a filtered blend coefficient for each sub-pixel element, the second filter applied to each sub-pixel element being spatially displaced from the second filters applied for the other sub-pixel elements, such that each filtered blend coefficient is derived from spatially different samples;

applying the foreground color and the background color to each of the filtered blend coefficients to generate color values associated with the sub-pixel elements;

mapping each color value to the sub-pixel element associated therewith, such that each sub-pixel element in a pixel has a different color value mapped thereto; and

displaying the image by separately controlling each sub-pixel element using the color value mapped thereto.

6. The method of claim 5 further comprising an act of gamma correcting the color values associated with the pixel sub-elements.

20. A machine readable medium having stored instructions which, when executed by a machine used in an system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different colors per pixel, performs the method of claim 5.

25. The method of claim 5, wherein:

the device having a plurality of pixels comprises a liquid crystal display device;

the plurality of separately controllable sub-pixel elements per pixel include a red sub-pixel element, a green sub-pixel element, and a blue sub-pixel element; and

the second filter applied for each of the sub-pixel elements is a box filter centered about the particular sub-pixel element for which the box filter is applied and extends to an adjacent sub-pixel element on either side of said particular sub-pixel element.

7. For use in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements per pixel, a method for improving spatial resolution of an image that is rendered by processing image information including blend coefficients defining a blend between a foreground color and a background color, the method comprising:

accepting a digital scan line of the image information representing discrete samples of an image, the discrete samples of the scan line including blend coefficients defining a blend between the foreground color and the background color and further including at least two samples of the blend coefficients per sub-pixel element;

applying first filters to sets of the samples of the blend coefficients in the digital scan line to generate new samples by filtering the at least two samples of the blend coefficients per sub-pixel element;

for each of the sub-pixel elements, applying second filters to the new samples to generate a filtered blend coefficient associated with each sub-pixel element, the second filter from which the filtered blend coefficient for a given sub-pixel element is derived being spatially displaced from the second filters applied for other sub-pixel elements, such that each filtered blend coefficient is derived from spatially different samples;

applying the foreground color and the background color to each of the filtered blend coefficients to generate color values associated with the sub-pixel elements;

mapping each color value to the sub-pixel element associated therewith, such that each sub-pixel element in a pixel has a different color value mapped thereto; and

displaying the image by separately controlling each sub-pixel element using the color value mapped thereto.

8. The method of claim 7 wherein the scan line includes exactly two samples per sub-pixel element.

9. The method of claim 7 wherein the second filters applied to the new samples comprise box filters, each of the box filters being centered at a spatial location corresponding to a sub-pixel element.

10. The method of claim 7 further comprising an act of gamma correcting the color values.

11. The method of claim 7 wherein at least one of the foreground and background color changes as a function of a position of the image.

21. A machine readable medium having stored instructions which, when executed by a machine used in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different colors per pixel, performs the method of claim 7.

22. A machine readable medium having stored instructions which, when executed by a machine used in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different color per pixel, performs the method of claim 8.

23. A machine readable medium having stored instructions which, when executed by a machine used in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different colors per pixel, performs the method of claim 11.

26. The method of claim 7, wherein:

the device having a plurality of pixels comprises a liquid crystal display device;

the plurality of separately controllable sub-pixel elements per pixel include a red sub-pixel element, a green sub-pixel element, and a blue sub-pixel element; and

the second filter applied for each of the sub-pixel elements is a box filter centered about the particular sub-pixel element for which the box filter is applied and extends to an adjacent sub-pixel element on either side of said particular sub-pixel element.

12. For use in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different colors per pixel, an apparatus for improving spatial resolution of an image that is rendered by processing image information, apparatus for processing image information, the apparatus comprising:

means for accepting digital scan lines of the image information representing a discrete values of an image, the scan lines including at least two color components, each said scan line comprising at least two samples per sub-pixel element, wherein each at least two samples correspond to one of the color components;

means for applying first filters to the digital scan lines to produce oversampled scan lines, wherein each oversampled scan line comprises at least two new samples for each sub-pixel component;

means, for each of the sub-pixel elements in each of the oversampled scan lines, for applying second filters to the new samples to generate a separate filtered color value associated with each sub-pixel element, the second filter from which the separate filtered color value for a given sub-pixel element is derived being spatially displaced from the second filters applied for other sub-pixel elements, such that each separate filtered color value is derived from spatially different samples of the oversampled scan lines;

means for mapping each separate filtered color value to the sub-pixel element associated therewith, such that each sub-pixel element in a pixel has a different separate filtered color value mapped thereto; and

means for displaying the image by separately controlling each sub-pixel element using the separate filtered color value mapped thereto.

13. The apparatus of claim 12 wherein each said scan line comprises exactly two samples per sub-pixel element.

14. For use in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements per pixel, an apparatus for improving spatial resolution of an image that is rendered by processing image information including blend coefficients defining a blend between a foreground color and a background color, the apparatus comprising:

means for accepting a digital scan line of the image information representing discrete samples of an image, the discrete samples of the scan line including blend coefficients defining a blend between the foreground color and the background color;

means for applying first filters to the digital scan line to produce an oversampled scan line for the blend coefficients, wherein the oversampled scan line comprises at least two new samples for each sub-pixel element; and

for each of the sub-pixel elements, means for applying a second filter to a set of at least two of the new samples of the blend coefficients to generate a filtered blend coefficient for each sub-pixel element, the second filter applied for each sub-pixel element being spatially displaced from the second filters applied for the other sub-pixel elements, such that each filtered blend coefficient is derived from spatially different samples;

means for applying the foreground color and the background color to each of the filtered blend coefficients to generate color values associated with the sub-pixel elements;

means for mapping each other value to the sub-pixel element associated therewith, such that each sub-pixel element in a pixel has a different color value mapped thereto; and

means for displaying the image by separately controlling each sub-pixel element using the color value mapped thereto.

15. For use in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements per pixel, an apparatus for improving spatial resolution of an image that is rendered by processing image information including blend coefficients defining a blend between a foreground color and a background color, the apparatus comprising:

means for accepting a digital scan line of the image information representing discrete samples of an image, the discrete samples of the scan line including blend coefficients defining a blend between the foreground color and the background color and further including at least two samples of the blend coefficients per sub-pixel element;

means for applying first filters to sets of the samples of the blend coefficients in the digital scan line to generate new samples by filtering the at least two samples of the blend coefficients per sub-pixel element;

means for each of the sub-pixel elements, for applying second filters to the new samples to generate a filtered blend coefficient associated with each sub-pixel element, the second filter from which the filtered blend coefficient for a given sub-pixel element is derived being spatially displaced from the second filters applied for other sub-pixel elements, such that each filtered blend coefficient is derived from spatially different samples;

means for applying the foreground color and the background color to each of the filtered blend coefficients to generate color values associated with the sub-pixel elements;

means for mapping each color value to the sub-pixel element associated therewith, such that each sub-pixel element in a pixel has a different color value mapped thereto; and

means for displaying the image by separately controlling each sub-pixel element using the color value mapped thereto.

16. The apparatus of claim 15 wherein the scan line includes exactly two samples per sub-pixel element.

17. The apparatus of claim 15 wherein at least one of the foreground and background color changes as a function of a position of the image.

27. For use in a system for rendering an image on a device having a plurality of pixels and a plurality of separately controllable sub-pixel elements of different colors per pixel, a method for generating color values for sub-pixel components to improve spatial resolution of the image, the method comprising:

accepting discrete values of one or more color scan lines, wherein the discrete values of each color scan line include one or more samples per sub-pixel component;

filtering the discrete values of each color scan line to generate an oversampled color scan line for each color scan line, wherein each oversampled scan line includes one or more new samples per sub-pixel component; and

applying box filters to the new samples of each oversampled color scan line to generate color values that are associated with each sub-pixel component, wherein the box filters of each oversampled color scan line are displaced with respect to other oversampled scan lines.

28. A method as defined in claim 27, wherein the box filters are centered at locations that correspond to centers of the sub-pixel components.

29. A method as defined in claim 27, further comprising applying gamma correction to the color values.