STRIPE PATTERN DETECTION SYSTEM, STRIPE PATTERN DETECTION METHOD, AND PROGRAM FOR STRIPE PATTERN DETECTION

• US 20110007163A1
• Filed: 03/18/2009
• Published: 01/13/2011
• Est. Priority Date: 03/19/2008
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Sakurai, Kazuyuki
• Granted Patent: US 8,432,447 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: G06V 20/588 Recognition of the road, e.g. of lane markings; Recognition of the vehicle driving pattern in relation to the road
• CPC Class Codes: G08G 1/16 Anti-collision systems road vehicle drive control systems for predicting or avoiding probable or impending collision otherwise than by control of a particular sub-unit B60W30/08
• CPC Class Codes: G08G 1/167 Driving aids for lane monitoring, lane changing, e.g. blind spot detection

Abstract

Disclosed is a detection system including a stripe pattern foreground filtering unit, a stripe pattern background filtering unit, a stripe pattern integration filtering unit, an isolated feature point removal unit, a stripe pattern area detection unit and a stripe pattern area outputting unit. The detection system utilizes a stripe pattern area filter value that directly exploits the shape of the stripe pattern in the local processing of each pixel in an image to detect the stripe pattern area.

Claims

1. A system for detecting a stripe pattern, comprising:

a stripe pattern foreground filter unit that calculates, for each pixel in an image, feature values, each representing an increment of a pixel value in a surrounding area of said each pixel from a pixel value outside of said surrounding area, as a size of said surrounding area is changed, to find a maximum value out of said feature values, said stripe pattern foreground filter unit allotting said maximum value as a stripe pattern foreground filter value, said stripe pattern foreground filter unit allotting a size of said surrounding area that gives said maximum value as a stripe pattern foreground width;

a stripe pattern background filter unit that calculates, for each pixel in an image, feature values, each representing a decrement of a pixel value in a surrounding area of said each pixel from a pixel value outside of said surrounding area, as a size of said surrounding area is changed, to find a maximum value out of said feature values, said stripe pattern background filter unit allotting said maximum value as a stripe pattern background filter value, said stripe pattern background filter unit allotting a size of said surrounding area that gives said maximum value as a stripe pattern background width;

a stripe pattern integration filter unit that calculates a stripe pattern integration filter value, for each pixel in said image, based on said stripe pattern foreground filter value in said pixel,

on said stripe pattern background filter value at a stripe pattern foreground end pixel that gives a maximum value out of said stripe pattern background filter values in a surrounding area of a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel, and

on said stripe pattern foreground filter value at a stripe pattern background end pixel that gives a maximum value out of said stripe pattern foreground filter values in a surrounding area of a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground end pixel; and

a stripe pattern area detection unit that decides, for each area in said image, whether or not a stripe pattern is contained in said each area, based on a feature value which is calculated from said stripe pattern integration filter value in said each area, said stripe pattern area detection unit outputting position information regarding said area in which said stripe pattern is contained, as stripe pattern area information.

2. The stripe pattern detection system according to claim 1, wherein said stripe pattern integration filter unit calculates said stripe pattern integration filter value, based further on said stripe pattern foreground width at said each pixel and on said stripe pattern foreground width at said stripe pattern background end pixel.

3. The stripe pattern detection system according to claim 1, wherein in said stripe pattern foreground filter unit, said surrounding area of said pixel is an area on a vertical line whose lower end is said each pixel, a size of said surrounding area being a width of said area on said vertical line, wherein

in said stripe pattern background filter unit,

said surrounding area of said each pixel is an area on a vertical line having said each pixel as a lower end, a size of said surrounding area being a width of said area on said vertical line, and wherein

in said stripe pattern integration filter unit,

a surrounding area of a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel is an area on a vertical line centered about a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel, and

a surrounding area of a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground end pixel is an area on a vertical line centered about a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to a stripe pattern background width at said stripe pattern foreground end pixel.

4. The stripe pattern detection system according to claim 1, wherein in said stripe pattern foreground filter unit, a feature value representing an increment of a pixel value in a surrounding area of said each pixel from a pixel value outside said surrounding area is a value obtained by subtracting a sum of pixel values outside of said surrounding area of said each pixel from a sum of pixel values in said surrounding area;

and wherein

in said stripe pattern background filter unit,

a feature value representing a decrement of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area is a value obtained by subtracting a sum of pixel values in said surrounding area of said each pixel from a sum of pixel values outside said surrounding area.

5. The stripe pattern detection system according to claim 1, wherein in said stripe pattern integration filter unit, said stripe pattern integration filter value is a minimum value out of said stripe pattern foreground filter value at said each pixel,

said stripe pattern background filter value at said stripe pattern foreground end pixel, and

said stripe pattern foreground filter value at said stripe pattern background end pixel.

6. The stripe pattern detection system according to claim 2, wherein in said stripe pattern integration filter unit, said stripe pattern integration filter value is a value obtained by dividing a minimum value out of

said stripe pattern foreground filter value at said each pixel,

said stripe pattern background filter value at said stripe pattern foreground end pixel, and

said stripe pattern foreground filter value at said stripe pattern background end pixel, by an absolute value of a difference between said stripe pattern foreground width at said each pixel and said stripe pattern foreground width at said stripe pattern background end pixel.

7. The stripe pattern detection system according to claim 3, wherein in case an amount of change of pixel values of upper and lower end pixels in an area along a vertical line whose lower end is said each pixel, along a direction of said vertical line, is not larger than a predetermined threshold value,

said stripe pattern foreground filter unit sets said stripe pattern foreground filter value and said stripe pattern foreground width to zero and refrains from calculating said stripe pattern foreground filter value and said stripe pattern foreground width;

and wherein

in case an amount of change of a pixel values of an upper and lower end pixels in an area along a vertical line whose lower end is said each pixel, along a direction of said vertical line, is not larger than a predetermined threshold value,

said stripe pattern background filter unit sets said stripe pattern background filter value and said stripe pattern background width to zero and refrains from performing calculations of said stripe pattern background filter value and said stripe pattern background width.

8. The stripe pattern detection system according to claim 1, wherein said image includes

a bird'"'"'s-eye image converted from an input original image for allowing to command bird'"'"'s eye view of a stripe pattern as a subject of detection.

9. The stripe pattern detection system according to claim 1, further comprising:

an isolated feature point removal unit that operates so that, if, among pixels in said image, having larger stripe pattern integration filter values, there exists an isolated pixel around which there is no pixel having a larger stripe pattern integration filter value,

said stripe pattern integration filter value of said isolated pixel will be replaced by a relatively small stripe pattern integration filter value.

10. The stripe pattern detection system according to claim 1, wherein said image from which to detect a stripe pattern includes

a road image photographed by a camera mounted on an own car or another car or provided on a road side;

and wherein

the stripe pattern being detected is a zebra zone on a road surface.

11. The stripe pattern detection system according to claim 10, wherein a lane partitioning line is detected from said road image;

and wherein

a surrounding area of said lane partitioning line is set to be a subject for zebra zone detection.

34. The stripe pattern detection system according to claim 1, wherein for said each pixel in said image, said stripe pattern foreground filter unit performs a first preset operation on pixel values in a first range on a vertical line having said each pixel as a lower end to calculate a stripe pattern foreground inner side feature value,

said stripe pattern foreground filter unit performing a second preset operation on pixel values in a second range on a vertical line having said each pixel as an upper end to calculate a stripe pattern foreground lower outer side feature value,

said stripe pattern foreground filter unit performing a third preset operation on pixel values in a third range on a vertical line having as a lower end an upper end of said second range on another vertical line whose upper end is said each pixel, to calculate a stripe pattern foreground upper outer side feature value,

said stripe pattern foreground filter unit performing a fourth preset operation on said stripe pattern foreground lower outer side feature value and on said stripe pattern foreground upper outer side feature value to calculate a stripe pattern foreground outer side feature value,

said stripe pattern foreground filter unit calculating, from said stripe pattern foreground inner side feature value and said stripe pattern foreground outer side feature value, such a feature value that becomes larger the higher a pixel value in said first range than a pixel value in said second range or a pixel value in said third range, as a stripe pattern foreground feature value,

said stripe pattern foreground filter unit calculating a plurality of said stripe pattern foreground feature values as a width of said second range is varied within a preset extent;

setting a maximum stripe pattern foreground feature value as a stripe pattern foreground filter value, and setting a width of said first range that gives said maximum stripe pattern foreground feature value as a stripe pattern foreground width.

35. The stripe pattern detection system according to claim 1, wherein said stripe pattern background filter unit performs a first preset operation on pixel values in a first range on a vertical line whose lower end is said each pixel, for said each pixel in said image, to calculate a stripe pattern background inner side feature value,

said stripe pattern background filter unit performing a second preset operation on pixel values in a second range on a vertical line whose upper end is said each pixel, for each said pixel in said image, to calculate a stripe pattern background outer lower side feature value,

said stripe pattern background filter unit performing a third preset operation on pixel values in a third range on a vertical line whose lower end is an upper end of a second range on another vertical line having said each pixel as an upper end to calculate a stripe pattern background upper outer side feature value,

said stripe pattern background filter unit performing a fourth preset operation on said stripe pattern background lower outer side feature value and on said stripe pattern background upper outer side feature value to calculate a stripe pattern background outer side feature value,

said stripe pattern background filter unit calculating, from said stripe pattern background inner side feature value and said stripe pattern background outer side feature value, such a feature value that becomes larger the lower a pixel value in said first range than a pixel value in said second range or a pixel value in said third range, as a stripe pattern background feature value,

said stripe pattern background filter unit calculating a plurality of said stripe pattern background feature values as a width of said second range is varied within a preset extent, said stripe pattern foreground filter unit setting a maximum stripe pattern background feature value as a stripe pattern background filter value, said stripe pattern background filter unit setting a width of said first range that gives said maximum stripe pattern background feature value as a stripe pattern background width.

36. The stripe pattern detection system according to claim 1, wherein

said stripe pattern integration filter unit detects, for said each pixel in said image, a stripe pattern foreground upper end candidate pixel having a maximum stripe pattern background filter value in a surrounding area of a pixel spaced apart upwards on a vertical line from said each pixel by a distance equal to a stripe pattern foreground width at said each pixel,

said stripe pattern integration filter unit detecting a stripe pattern background upper end candidate pixel having a maximum stripe pattern background filter value in a surrounding area of a pixel spaced apart upwards from said stripe pattern foreground upper end candidate pixel on a vertical line by a distance equal to a stripe pattern background width at said stripe pattern foreground upper end candidate pixel,

said stripe pattern integration filter unit performing a fifth preset operation on stripe pattern foreground filter values at said each pixel and at said stripe pattern background upper end candidate pixel and on a stripe pattern background filter value at said stripe pattern foreground upper end candidate pixel to calculate a stripe pattern foreground/background filter feature value,

said stripe pattern integration filter unit performing a sixth preset operation on said stripe pattern foreground widths at said each pixel and at said stripe pattern background upper end candidate pixel to calculate a stripe pattern foreground uniform width feature value,

said stripe pattern integration filter unit performing a seventh preset operation on said stripe pattern foreground/background filter feature value and said stripe pattern foreground uniform width feature value to calculate a stripe pattern integration filter value.

37. The stripe pattern detection system according to claim 34, wherein said first preset operation finds a sum or a minimum value, and

said second, third and fourth preset operations find a mean value or a maximum value.

38. The stripe pattern detection system according to claim 36, wherein said fifth preset operation finds a sum or a minimum value,

said sixth preset operation finds a difference, and

said seventh preset operation divides said stripe pattern foreground/background filter feature value by said stripe pattern foreground uniform width feature value.

39. The stripe pattern detection system according to claim 1, wherein said stripe pattern integration filter unit detects, for said each pixel in said image,

a stripe pattern foreground upper end candidate pixel, having a maximum stripe pattern background filter value, in a surrounding area of a pixel spaced apart upwards on a vertical line from said each pixel by a distance corresponding to a stripe pattern foreground width at said each pixel,

said stripe pattern integration filter unit detecting a stripe pattern background upper end candidate pixel, having a maximum stripe pattern background filter value, in a surrounding area of a pixel spaced apart upwards on a vertical line from said stripe pattern foreground upper end candidate pixel by a distance corresponding to a stripe pattern background width at said stripe pattern foreground upper end candidate pixel,

said stripe pattern integration filter unit setting a feature value, as a result of said preset operation on the stripe pattern foreground filter values at said each pixel and at said stripe pattern foreground upper end candidate pixel and on a stripe pattern background filter value at said stripe pattern foreground upper end candidate pixel, to be a stripe pattern foreground/background filter feature value,

said stripe pattern integration filter unit setting feature values, as results of preset operations on a stripe pattern foreground width at said each pixel and on a stripe pattern foreground width at said stripe pattern background upper end candidate pixel, to be a stripe pattern foreground uniform width,

said stripe pattern integration filter unit setting a feature value, as results of preset operations on a stripe pattern foreground/background filter feature value and said stripe pattern foreground uniform width feature value, to be said stripe pattern integration filter value.

12. A method for detecting a stripe pattern, comprising:

calculating, for each pixel in an image, feature values, each representing an increment of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area, as a size of said surrounding area is changed, to find a maximum value out of said feature values, allotting said maximum value as a stripe pattern foreground filter value, and allotting a size of said surrounding area that gives said maximum value as being a stripe pattern foreground width;

calculating, for each pixel in said image, feature values, each representing a decrement of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area, as a size of said surrounding area is changed, to find a maximum value out of said feature values, allotting said maximum value as a stripe pattern background filter value, and allotting a size of said surrounding area that gives said maximum value as being a stripe pattern background width;

calculating a stripe pattern integration filter value at each pixel in said image, based

on said stripe pattern foreground filter value in said each pixel,

on said stripe pattern background filter value at a stripe pattern foreground end pixel that gives a maximum value out of said stripe pattern background filter values in a surrounding area of a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel, and

on said stripe pattern foreground filter value at a stripe pattern background end pixel that gives a maximum value out of said stripe pattern foreground filter values in a surrounding area of a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground end pixel;

deciding, for each area in said image, whether or not a stripe pattern is contained in said each area, from a feature value calculated from said stripe pattern integration filter value in said each area; and

outputting position information regarding said area, in which said stripe pattern is contained as stripe pattern area information.

13. The stripe pattern detection method according to claim 12, comprising

calculating said stripe pattern integration filter value based further on said stripe pattern foreground width at said each pixel and on said stripe pattern foreground width at said stripe pattern background end pixel.

14. The stripe pattern detection method according to claim 12, wherein said surrounding area of said each pixel is an area on a vertical line whose lower end is said each pixel, a size of said surrounding area being a width of said area on a vertical line;

wherein

a surrounding area of a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel is an area on a vertical line centered about a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel; and

wherein

a surrounding area of a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground end pixel being an area on a vertical line centered about a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground end pixel.

15. The stripe pattern detection method according to claim 12, wherein a feature value representing an increment of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area is a value obtained by subtracting a sum of pixel values outside said surrounding area of said each pixel from a sum of pixel values in said surrounding area;

and wherein

the feature value representing a decrement of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area is a value obtained by subtracting a sum of pixel values in said surrounding area of said each pixel from a sum of pixel values outside said surrounding area.

16. The stripe pattern detection system according to claim 12, wherein said stripe pattern integration filter value is a minimum value out of

said stripe pattern foreground filter value at said each pixel,

said stripe pattern background filter value at said stripe pattern foreground end pixel, and

said stripe pattern foreground filter value at said stripe pattern background end pixel.

17. The stripe pattern detection method according to claim 13, wherein said stripe pattern integration filter value is a value obtained by dividing a minimum value out of

said stripe pattern foreground filter value at said each pixel,

said stripe pattern background filter value at said stripe pattern foreground end pixel, and

said stripe pattern foreground filter value at said stripe pattern background end pixel, by

an absolute value of a difference between said stripe pattern foreground width at said each pixel and said stripe pattern background width at said stripe pattern background end pixel.

18. The stripe pattern detection method according to claim 14, wherein, if an amount of change of pixel values of upper and lower end pixels in an area along a vertical line whose lower end is said each pixel, along a direction of said vertical line, is not larger than a predetermined threshold value,

said stripe pattern foreground filter value and said stripe pattern foreground width are set to zero and said stripe pattern foreground filter value or said stripe pattern foreground width is not calculated;

and wherein

if an amount of change of pixel values of upper and lower end pixels in an area along a vertical line whose lower end is said each pixel, along a direction of said vertical line, is not larger than a predetermined threshold value,

said stripe pattern background filter value and said stripe pattern background width are set to zero and said stripe pattern background filter value or said stripe pattern background width is not calculated.

19. The stripe pattern detection method according to claim 12, wherein said image includes a bird'"'"'s-eye image converted from an input original image to command a bird'"'"'s eye view of a stripe pattern as a subject of detection.

20. The stripe pattern detection method according to claim 12, wherein, if, among pixels in said image, having larger stripe pattern integration filter values, there exists an isolated pixel around which there is no pixel having a larger stripe pattern integration filter value, said stripe pattern integration filter value of said isolated pixel is replaced by a relatively small stripe pattern integration filter value.

21. The stripe pattern detection method according to claim 12, wherein said image from which to detect a stripe pattern includes a road image photographed by a camera mounted on an own car or another car or provided on a road side;

and wherein

the stripe pattern being detected is a zebra zone on a road surface.

22. The stripe pattern detection system according to claim 21, wherein a lane partitioning line is detected from a road image;

and wherein

a surrounding area of said lane partitioning line is set to be a subject for zebra zone detection.

23. A computer-readable recording medium storing a program that causes a computer to execute

a stripe pattern foreground filtering processing of calculating, for each pixel in an image, feature values, each representing an increment of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area, as a size of said surrounding area is changed, to find a maximum value out of said feature values, allotting said maximum value as a stripe pattern foreground filter value, and allotting a size of said surrounding area that gives said maximum value as being a stripe pattern foreground width;

a stripe pattern background filtering processing of calculating, for each pixel in said image, feature values, each representing a decrement of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area, as a size of said surrounding area is changed, to find a maximum value out of said feature values, allotting said maximum value as a stripe pattern background filter value, and allotting a size of said surrounding area that gives said maximum value as being a stripe pattern background width;

a stripe pattern integration filtering processing of calculating and allotting a stripe pattern integration filter value at each pixel in said image, based on said stripe pattern foreground filter value in said each pixel,

on said stripe pattern background filter value at a stripe pattern foreground end pixel that gives a maximum value out of said stripe pattern background filter values in a surrounding area of a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel, and

on said stripe pattern foreground filter value at a stripe pattern background end pixel that gives a maximum value out of said stripe pattern foreground filter values in a surrounding area of a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground end pixel; and

a stripe pattern detection processing of deciding, for each area in said image, whether or not a stripe pattern is contained in said each area, from a feature value calculated from said stripe pattern integration filter value in said each area, and outputting position information regarding said area containing said stripe pattern as stripe pattern area information.

24. The computer-readable recording medium storing the program according to claim 23, wherein in said stripe pattern integration filtering processing, said stripe pattern integration filter value is calculated based further on said stripe pattern foreground width at said each pixel and on said stripe pattern foreground width at said stripe pattern background end pixel.

25. The computer-readable recording medium storing the program according to claim 23, wherein in said stripe pattern foreground filtering processing, said surrounding area of said each pixel is an area on a vertical line whose lower end is said each pixel, a size of said surrounding area is a width of said area on a vertical line;

wherein

in said stripe pattern background filtering processing, a surrounding area of said each pixel is an area on a vertical line whose lower end is said each pixel, a size of said surrounding area is a width of said area on a vertical line; and

wherein

in said stripe pattern integration filtering processing,

a surrounding area of a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel is an area on a vertical line centered about a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel, and

a surrounding area of a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground end pixel is an area on a vertical line centered about a pixel spaced apart from said stripe pattern foreground end pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground end pixel.

26. The computer-readable recording medium storing the program according to claim 23, wherein in said stripe pattern foreground filtering processing, a feature value representing an increment of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area is a value obtained by subtracting a sum of pixel values outside said surrounding area of said each pixel from a sum of pixel values in said surrounding area;

and wherein

in said stripe pattern background filtering processing, a feature value representing a decrement of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area is a value obtained by subtracting a sum of pixel values in said surrounding area of said each pixel from a sum of pixel values outside said surrounding area.

27. The computer-readable recording medium storing the program according to claim 23, wherein, in said stripe pattern integration filtering processing, said stripe pattern integration filter value is a minimum value out of said stripe pattern foreground filter value at said each pixel,

said stripe pattern background filter value at said stripe pattern foreground end pixel, and

said stripe pattern foreground filter value at said stripe pattern background end pixel.

28. The computer-readable recording medium storing the program according to claim 24, wherein, in said stripe pattern integration filtering processing, said stripe pattern integration filter value is a value obtained by dividing a minimum value out of

said stripe pattern foreground filter value at said each pixel,

said stripe pattern background filter value at said stripe pattern foreground end pixel, and

said stripe pattern foreground filter value at said stripe pattern background end pixel, by

an absolute value of a difference between said stripe pattern foreground width at said each pixel and said stripe pattern foreground width at said stripe pattern background end pixel.

29. The computer-readable recording medium storing the program according to claim 25, wherein, if, in said stripe pattern foreground filtering processing, an amount of change of pixel values of upper and lower end pixels in an area along a vertical line whose lower end is said each pixel, along a direction of said vertical line, is not larger than a predetermined threshold value,

said stripe pattern foreground filter value and said stripe pattern foreground width are set to zero and said stripe pattern foreground filter value or said stripe pattern foreground width is not calculated;

and wherein

if, in said stripe pattern background filtering processing, an amount of change of pixel values of upper and lower end pixels in an area along a vertical line whose lower end is said each pixel, along a direction of said vertical line, is not larger than a predetermined threshold value,

said stripe pattern background filter value and said stripe pattern background width are set to zero and said stripe pattern background filter value or said stripe pattern background width is not calculated.

30. The computer-readable recording medium storing the program according to claim 23, wherein said image includes a bird'"'"'s-eye image converted from an input original image for allowing to command a bird'"'"'s eye view of a stripe pattern as a subject of detection.

31. The computer-readable recording medium storing the program according to claim 23, wherein said program further causes a computer to execute

an isolated feature point removal processing in which, if, among pixels in said image, having larger stripe pattern integration filter values, there exists an isolated pixel around which there is no pixel having a larger stripe pattern integration filter value, said stripe pattern integration filter value of said isolated pixel is replaced by a relatively small stripe pattern integration filter value.

32. The computer-readable recording medium storing the program according to claim 23, wherein said image from which to detect a stripe pattern includes a road image photographed by a camera mounted on an own car or another car or provided on a road side;

and wherein

a stripe pattern being detected is a zebra zone on a road surface.

33. The computer-readable recording medium storing the program according to claim 32, wherein a lane partitioning line is detected from a road image;

and wherein

a surrounding area of said lane partitioning line is set to be a subject for zebra zone detection.

40. A system for detection of a stripe pattern comprising:

a stripe pattern foreground filter unit that calculates, for each pixel in an image, feature values, each representing an increment of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area, as a size of said surrounding area is changed,

said stripe pattern foreground filter unit finding, as a stripe pattern foreground filter value, such feature value out of said feature values that satisfies a preset condition regarding a certain large-small relationship,

said stripe pattern foreground filter unit finding a width of said surrounding area corresponding to said stripe pattern foreground filter value as being a stripe pattern foreground width,

a stripe pattern background filter unit that calculates, for each pixel in said image, feature values, each representing a decrement of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area, as a size of said surrounding area is changed,

said stripe pattern background filter unit finding, as a stripe pattern background filter value, such feature value out of said feature values that satisfies a preset condition regarding a certain large-small relationship,

said stripe pattern background filter unit finding a width of said surrounding area corresponding to said stripe pattern background filter value as being a stripe pattern background width;

a stripe pattern integration filter unit that detects, in a surrounding area of a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel in said image, a stripe pattern foreground upper end candidate pixel for which said stripe pattern background filter value satisfies a preset condition regarding a certain large-small relationship,

said stripe pattern integration filter unit detecting, in a surrounding area of a pixel spaced apart from said stripe pattern foreground upper end candidate pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground upper end candidate pixel, a stripe pattern background upper end candidate pixel for which said stripe pattern background filter value satisfies a preset condition regarding a certain large-small relationship,

said stripe pattern integration filter unit setting a feature value, which is a result of a preset operation on stripe pattern foreground filter values at said each pixel and at said stripe pattern background upper end candidate pixel, and on a stripe pattern background filter value at said stripe pattern foreground upper end candidate pixel, to be a stripe pattern foreground/background filter feature value,

said stripe pattern integration filter unit setting a feature value, which is a result of a preset operation on said stripe pattern foreground width at said each pixel and on said stripe pattern foreground width at said stripe pattern background upper end candidate pixel, to be a stripe pattern foreground uniform width feature value;

said stripe pattern integration filter unit setting a feature value, which is a result of a preset operation on said stripe pattern foreground/background filter feature value and on said stripe pattern foreground uniform width feature value, to be said stripe pattern integration filter value; and

a stripe pattern area detection unit that checks, from a feature value calculated from said stripe pattern integration filter value in an area in said image, whether or not a stripe pattern is contained in said area;

said stripe pattern area detection unit outputting position information regarding an area in which said stripe pattern is contained as stripe pattern area information.

41. A method for detection of a stripe pattern comprising:

calculating, for each pixel in an image, feature values, each representing an increment of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area, as a size of said surrounding area is changed, finding, as a stripe pattern foreground filter value, such feature value out of said feature values that satisfies a preset condition regarding a certain large-small relationship, and finding a width of said surrounding area corresponding to said stripe pattern foreground filter value as being a stripe pattern foreground width;

calculating, for each pixel in said image, feature values, each representing a decrement of a pixel value in a surrounding area of said each pixel from pixel values outside of said surrounding area, as a size of said surrounding area is changed, finding, as a stripe pattern background filter value, such feature value out of said feature values that satisfies a preset condition regarding a certain large-small relationship, and finding a width of said surrounding area corresponding to said stripe pattern background filter value as being a stripe pattern background width;

detecting, in a surrounding area of a pixel spaced apart from said each pixel by a distance corresponding to said stripe pattern foreground width at said each pixel in said image, a stripe pattern foreground upper end candidate pixel for which said stripe pattern background filter value satisfies a preset condition regarding a certain large-small relationship;

detecting, in a surrounding area of a pixel spaced apart from said stripe pattern foreground upper end candidate pixel by a distance corresponding to said stripe pattern background width at said stripe pattern foreground upper end candidate pixel, a stripe pattern background upper end candidate pixel for which said stripe pattern background filter value satisfies a preset condition regarding a certain large-small relationship;

setting a feature value, which is a result of a preset operation on stripe pattern foreground filter values at said each pixel and at said stripe pattern background upper end candidate pixel, and on a stripe pattern background filter value at said stripe pattern foreground upper end candidate pixel, to be a stripe pattern foreground/background filter feature value;

setting a feature value, which is a result of a preset operation on said stripe pattern foreground width at said each pixel and on said stripe pattern foreground width at said stripe pattern background upper end candidate pixel, to be a stripe pattern foreground uniform width feature value;

setting a feature value, which is a result of a preset operation on said stripe pattern foreground/background filter feature value and on said stripe pattern foreground uniform width feature value, to be said stripe pattern integration filter value;

deciding, from a feature value calculated from said stripe pattern integration filter value in an area in said image, whether or not a stripe pattern is contained in said area; and

outputting position information regarding an area in which said stripe pattern is contained as stripe pattern area information.