Method of and apparatus for displaying a multicolor image

• US 5,341,153 A
• Filed: 06/13/1988
• Issued: 08/23/1994
• Est. Priority Date: 06/13/1988
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Benzschawel, Terry L., Howard, Webster E.
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Saras, Steven J.
• Application Number:
  US07/205,961
• Time in Patent Office: 2,262 Days
• Field of Search: 340/703, 340/702, 340/701, 340/728, 340/784, 340/793, 358/56, 358/59, 358/166, 382/27, 359/53, 359/55, 359/56, 359/59, 395/131, 345/88, 345/136, 345/137, 345/138, 345/150, 345/151, 345/152
• US Class Current: 345/694
• CPC Class Codes: G02F 1/133514 Colour filters
• 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 2340/0457 Improvement of perceived resolution by subpixel rendering
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 9/12 Picture reproducers H04N9/11 takes precedence

Abstract

A method of displaying a high resolution multicolor image on a lower resolution display. The image comprises a plurality of image pixels containing at least first and second image subpixels having first and second colors. The image is displayed on a display having display pixels comprising at least first and second spatially offset display subpixels capable of displaying the first and second colors, respectively. In the method, the first display subpixel is displayed with an intensity which is a function of the intensities of at least two first image subpixels having positions extending over a first region having an area greater than the area of the first display subpixel. The first region is approximately centered on the position of the first display subpixel. A second display subpixel is displayed with an intensity which is a function of the intensities of at least two second image subpixels having positions extending over a second region having an area greater than the area of the second display subpixel. The second region is approximately centered on the position of the second display subpixel. By using a different centered region for each separate subpixel of a composite RGB display picture element in transforming a high resolution multicolor image to a lower resolution display, higher quality images are produced as compared to using a single region for each composite RGB display picture element.

Claims

1. A method of displaying a multicolor image, said method comprising the steps of:

providing an image having a first density of image pixels, each image pixel having a position, each image pixel comprising at least first and second image subpixels, each first image subpixel having a first color, each second image subpixel having a second color different from the first color, each image subpixel having an intensity;

providing a display having a second density of display pixels less than or equal to the first density of image pixels, each display signal comprising at least first and second spatially offset display subpixels, each first display subpixel being capable of displaying the first color, each second display subpixel being capable of displaying the second color, each display subpixel having a position and an area, each display subpixel corresponding to an area of the display;

displaying a first display subpixel with an intensity which is a function of the intensities of at least two first image subpixels having positions extending over a first region, said first region being approximately centered on the position of the first display subpixel, said first region having an area greater than the area of the first display subpixel; and

displaying a second display subpixel with an intensity which is a function of the intensities of at least two second image subpixels having positions extending over a second region, said second region being approximately centered on the position of the second display subpixel, said second region having an area greater than the area of the second display subpixel.

2. A method as claimed in claim 1, characterized in that:

each image subpixel has one of only two intensity levels; and

each display subpixel is capable of being displayed in any one of at least three intensity levels.

3. A method as claimed in claim 2, characterized in that:

each first display subpixel is displayed with an intensity which is a first function of the intensities of at least two first image subpixels having positions extending over a first region associated with the first display subpixel, each first region having an area greater than the area of the associated first display subpixel, each first region being approximately centered on the position of the associated first display subpixel; and

each second display subpixel is displayed with an intensity which is a second function of the intensities of at least two second image subpixels having positions extending over a second region associated with the second display subpixel, each second region having an area greater than the area of the associated second display subpixel, each second region being approximately centered on the position of the associated second display subpixel.

4. A method as claimed in claim 3, characterized in that:

each image pixel further comprises a third image subpixel, each third image subpixel having a third color different from the first and second colors;

each display pixel further comprises a third display subpixel spatially offset from the first and second display subpixels, each third display subpixel being capable of displaying the third color; and

the method further comprises the step of displaying each third display subpixel with an intensity which is a third function of the intensities of at least two third image subpixels having positions extending over a third region associated with the third display subpixel, each third region having an area greater than the area of the associated third display subpixel, each third region being approximately centered on the position of the associated third display subpixel.

5. A method as claimed in claim 4, characterized in that the first, second, and third regions are T-shaped and have equal areas.

6. A method as claimed in claim 4, characterized in that the first, second, and third regions are rectangularly shaped and have equal areas.

7. A method as claimed in claim 4, characterized in that the first, second, and third regions have equal areas.

8. A method as claimed in claim 4, characterized in that the first, second, and third functions are weighted arithmetic mean functions.

9. A method as claimed in claim 4, characterized in that the steps of displaying the display subpixels comprise the steps of energizing the display subpixels to emit light.

10. A method as claimed in claim 4, characterized in that the steps of displaying the display subpixels comprise the steps of energizing the display subpixels to reflect light incident thereon.

11. A method as claimed in claim 4, characterized in that the steps of displaying the display subpixels comprise the steps of energizing the display subpixels to transmit light incident thereon.

12. A method as claimed in claim 4, characterized in that:

the intensity of the first display subpixel is equal to a low-pass filter function of the spatial distribution of the intensities of the first image subpixels in the first region;

the intensity of the second display subpixel is equal to a low-pass filter function of the spatial distribution of the intensities of the first image subpixels in the second region; and

the intensity of the third display subpixel is equal to a low pass filter function of the spatial distribution of the intensities of the first image subpixels in the third region.

13. A method as claimed in claim 3, characterized in that the first and second image subpixels are spatially superimposed on each other.

14. A method as claimed in claim 3, characterized in that the second density of display pixels is less than the first density of image pixels.

15. A method as claimed in claim 3, characterized in that:

the display has an area;

each display pixel has an area, the area of one display pixel being substantially equal to the area of each other display subpixel, the sum of the areas of the display pixels being substantially equal to the display area;

each first region has an area substantially equal to the area of a display pixel;

each second region has an area substantially equal to the area of a display pixel;

a combination of all of the first regions extends over substantially the entire display;

a combination of all of the second regions extends over substantially the entire display;

the sum of the areas of all of the first regions is substantially equal to the display area; and

the sum of the areas of all of the second regions is substantially equal to the display area.

16. A method as claimed in claim 1, characterized in that:

each first display subpixel is displayed with an intensity which is a first function of the intensities of at least two first image subpixels having positions extending over a first region associated with the first display subpixel, each first region having an area greater than the area of the associated first display subpixel, each first region being approximately centered on the position of the associated first display subpixel; and

each second display subpixel is displayed with an intensity which is a second function of the intensities of at least two second image subpixels having positions extending over a second region associated with the second display subpixel, each second region having an area greater than the area of the associated second display subpixel, each second region being approximately centered on the position of the associated second display subpixel.

17. A method as claimed in claim 16, characterized in that:

each image pixel further comprises a third image subpixel, each third image subpixel having a third color different from the first and second colors;

each display pixel further comprises a third display subpixel spatially offset from the first and second display subpixels, each third display subpixel being capable of displaying the third color; and

the method further comprises the step of displaying each third display subpixel with an intensity which is a third function of the intensities of at least two third image subpixels having positions extending over a third region associated with the third display subpixel, each third region having an area greater than the area of the associated third display subpixel, each third region being approximately centered on the position of the associated third display subpixel.

18. A method as claimed in claim 17, characterized in that the first, second, and third regions are T-shaped and have equal areas.

19. A method as claimed in claim 17, characterized in that the first, second, and third regions are rectangularly shaped and have equal areas.

20. A method as claimed in claim 17, characterized in that the first, second, and third regions have equal areas.

21. A method as claimed in claim 17, characterized in that the first, second, and third functions are weighted arithmetic mean functions.

22. A method as claimed in claim 17, characterized in that the steps of displaying the display subpixels comprise the steps of energizing the display subpixels to emit light.

23. A method as claimed in claim 17, characterized in that the steps of displaying the display subpixels comprise the steps of energizing the display subpixels to reflect light incident thereon.

24. A method as claimed in claim 17, characterized in that the steps of displaying the display subpixels comprise the steps of energizing the display subpixels to transmit light incident thereon.

25. A method as claimed in claim 17, characterized in that:

the intensity of the first display subpixel is equal to a low-pass filter function of the spatial distribution of the intensities of the first image subpixels in the first region;

the intensity of the second display subpixel is equal to a low-pass filter function of the spatial distribution of the intensities of the first image subpixels in the second region; and

the intensity of the third display subpixel is equal to a low pass filter function of the spatial distribution of the intensities of the first image subpixels in the third region.

26. A method as claimed in claim 16, characterized in that

each image pixel further comprises a fourth image subpixel, each fourth image subpixel having a fourth color different from the first, second, and third colors;

each display pixel further comprises a fourth display subpixel spatially offset from the first, second, and third display subpixels, each fourth display subpixel being capable of displaying the fourth color; and

the method further comprises the step of displaying each fourth display subpixel with an intensity which is a fourth function of the intensities of at least two fourth image subpixels having positions extending over a fourth region associated with the fourth display subpixel, each fourth region having an area greater than the area of the associated fourth display subpixel, each fourth region being approximately centered on the position of the associated fourth display subpixel.

27. A method as claimed in claim 16, characterized in that the first and second image subpixels are spatially superimposed on each other.

28. A method as claimed in claim 16, characterized in that the second density of display pixels is less than the first density of image pixels.

29. An apparatus for displaying a multicolor image, said apparatus comprising:

means for providing image information corresponding to an image having a first density of image pixels, each image pixel having a position, each image pixel comprising at least first and second image subpixels, each first image subpixel having a first color, each second image subpixel having a second color different from the first color, each image subpixel having an intensity;

a display having a second density of display pixels less than or equal to the first density of image pixels, each display pixel comprising at least first and second spatially offset display subpixels, each first display subpixel being capable of displaying the first color, each second display subpixel being capable of displaying the second color, each display subpixel having a position and an area, each display subpixel corresponding to an area of the display;

means for displaying a first display subpixel with an intensity which is a function of the intensities of at least two first image subpixels having positions extending over a first region, said first region being approximately centered on the position of the first display subpixel, said first region having an area greater than the area of the first display subpixel; and

means for displaying a second display subpixel with an intensity which is a function of the intensities of at least two second image subpixels having positions extending over a second region, said second region being approximately centered on the position of the second display subpixel, said second region having an area greater than the area of the second display subpixel.

30. An apparatus as claimed in claim 29, characterized in that:

the means for providing image information comprises an image memory for storing image information;

each image subpixel has one of only two intensity levels; and

each display subpixel is capable of being displayed in any one of at least three intensity levels.

31. An apparatus as claimed in claim 30, characterized in that:

each first display subpixel is displayed with an intensity which is a first function of the intensities of at least two first image subpixels having positions extending over a first region associated with the first display subpixel, each first region having an area greater than the area of the associated first display subpixel, each first region being approximately centered on the position of the associated first display subpixel; and

each second display subpixel is displayed with an intensity which is a second function of the intensities of at least two second image subpixels having positions extending over a second region associated with the second display subpixel, each second region having an area greater than the area of the associated second display subpixel, each second region being approximately centered on the position of the associated second display subpixel.

32. An apparatus as claimed in claim 31, characterized in that:

each image pixel further comprises a third image subpixel, each third image subpixel having a third color different from the first and second colors;

each display pixel further comprises a third display subpixel spatially offset from the first and second display subpixels, each third display subpixel being capable of displaying the third color; and

the apparatus further comprises means for displaying each third display subpixel with an intensity which is a third function of the intensities of at least two third image subpixels having positions extending over a third region associated with the third display subpixel, each third region having an area greater than the area of the associated third display subpixel, each third region being approximately centered on the position of the associated third display subpixel.

33. An apparatus as claimed in claim 32, characterized in that the first, second, and third regions are T-shaped and ave equal areas.

34. An apparatus as claimed in claim 32, characterized in that the first, second, and third regions are rectangularly shaped and have equal areas.

35. An apparatus as claimed in claim 32, characterized in that the first, second, and third regions have equal areas.

36. An apparatus as claimed in claim 32, characterized in that the first, second, and third functions are weighted arithmetic mean functions.

37. An apparatus as claimed in claim 32, characterized in that the means for displaying the display subpixels comprises means for energizing the display subpixels to emit light.

38. An apparatus as claimed in claim 32, characterized in that the means for displaying the display subpixels comprises means for energizing the display subpixels to reflect light incident thereon.

39. An apparatus as claimed in claim 32, characterized in that the means for displaying the display subpixels comprises means for of energizing the display subpixels to transmit light incident thereon.

40. An apparatus as claimed in claim 32, characterized in that:

the intensity of the first display subpixel is equal to a low-pass filter function of the spatial distribution of the intensities of the first image subpixels in the first region;

the intensity of the second display subpixel is equal to a low-pass filter function of the spatial distribution of the intensities of the first image subpixels in the second region; and

the intensity of the third display subpixel is equal to a low pass filter function of the spatial distribution of the intensities of the first image subpixels in the third region.

41. An apparatus as claimed in claim 31, characterized in that the first and second image subpixels are spatially superimposed on each other.

42. All apparatus as claimed in claim 31, characterized in that the second density of display pixels is less than the first density of image pixels.

43. An apparatus as claimed in claim 31, characterized in that:

the display has an area;

each display pixel has an area, the area of one display pixel being substantially equal to the area of each other display subpixel, the sum of the areas of the display pixels being substantially equal to the display area;

each first region has an area substantially equal to the area of a display pixel;

each second region has an area substantially equal to the area of a display pixel;

a combination of all of the first regions extends over substantially the entire display;

a combination of all of the second regions extends over substantially the entire display;

the sum of the areas of all of the first regions is substantially equal to the display area; and

the sum of the areas of all of the second regions is substantially equal to the display area.