Method and apparatus for detecting positions of center points of circular patterns

A method of detecting a position of a center point of a circular pattern, in which a position of a center point of a circular pattern contained in a photographic image is detected from the photographic image, the method comprising the steps of:

• i) performing voting of coordinates of all pixels in the photographic image onto a Hough space corresponding to annuluses, which Hough space is defined by a coordinate system having an X coordinate axis for a center point of a circle, a Y coordinate axis for a center point of a circle, and an r coordinate axis for a radial direction,
• ii) acquiring a vote value of each of voting positions having coordinates (X, Y, r) on the Hough space from a calculation of a number of votes having been given to each of the voting positions having the coordinates (X, Y, r) on the Hough space, a plurality of vote values being obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space,
• iii) adding the vote values of voting positions, which have identical (X, Y) coordinate values on the Hough space among the voting positions having the coordinates (X, Y, r) on the Hough space, to one another, a second integrated vote value being obtained from the addition and with respect to the voting positions, which have the identical (X, Y) coordinate values on the Hough space, a plurality of second integrated vote values being obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, and
• iv) detecting a position, which is represented by (X, Y) coordinate values corresponding to the largest second integrated vote value among the plurality of the second integrated vote values having been obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, as the position of the center point of the circular pattern,
• wherein weighted addition is performed on the number of votes having been given by all of the pixels in the photographic image, and wherein the number of a vote given by a pixel having a high chromatic color degree is assigned with a weight lighter than the weight assigned to the number of a vote given by a pixel having a low chromatic color degree, and
• a value having been obtained from the weighted addition is taken as the vote value.

An apparatus for detecting a position of a center point of a circular pattern, in which a position of a center point of a circular pattern contained in a photographic image is detected from the photographic image, the apparatus comprising:

• i) vote value acquiring means for:
• performing voting of coordinates of all pixels in the photographic image onto a Hough space corresponding to annuluses, which Hough space is defined by a coordinate system having an X coordinate axis for a center point of a circle, a Y coordinate axis for a center point of a circle, and an r coordinate axis for a radial direction, and
• acquiring a vote value of each of voting positions having coordinates (X, Y, r) on the Hough space from a calculation of a number of votes having been given to each of the voting positions having the coordinates (X, Y, r) on the Hough space, the thus acquired vote value being taken as a first integrated vote value, a plurality of first integrated vote values being obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, and
• ii) center position detecting means for detecting a position, which is represented by (X, Y) coordinate values of a voting position associated with the largest first integrated vote value among the plurality of the first integrated vote values having been obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, as the position of the center point of the circular pattern,
• wherein weighted addition is performed on the number of votes having been given by all of the pixels in the photographic image, and wherein the number of a vote given by a pixel having a high chromatic color degree is assigned with a weight lighter than the weight assigned to the number of a vote given by a pixel having a low chromatic color degree, and
• a value having been obtained from the weighted addition is taken as the vote value.

An apparatus for detecting a position of a center point of a circular pattern, in which a position of a center point of a circular pattern contained in a photographic image is detected from the photographic image, the apparatus comprising:

• i) vote value acquiring means for:
• performing voting of coordinates of all pixels in the photographic image onto a Hough space corresponding to annuluses, which Hough space is defined by a coordinate system having an X coordinate axis for a center point of a circle, a Y coordinate axis for a center point of a circle, and an r coordinate axis for a radial direction, and
• acquiring a vote value of each of voting positions having coordinates (X, Y, r) on the Hough space from a calculation of a number of votes having been given to each of the voting positions having the coordinates (X, Y, r) on the Hough space, a plurality of vote values being obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space,
• ii) vote value integrating means for adding the vote values of voting positions, which have identical (X, Y) coordinate values on the Hough space among the voting positions having the coordinates (X, Y, r) on the Hough space, to one another, a second integrated vote value being obtained from the addition and with respect to the voting positions, which have the identical (X, Y) coordinate values on the Hough space, a plurality of second integrated vote values being obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, and
• iii) center position detecting means for detecting a position, which is represented by (X, Y) coordinate values corresponding to the largest second integrated vote value among the plurality of the second integrated vote values having been obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, as the position of the center point of the circular patterns,
• wherein weighted addition is performed on the number of votes having been given by all of the pixels in the photo graphic image, and wherein the number of a vote given by a pixel having a high chromatic color degree is assigned with a weight lighter than the weight assigned to the number of a vote given by a pixel having a low chromatic color degree, and
• a value having been obtained from the weighted addition is taken as the vote value.

A computer recording medium storing a program which, when executed by a computer, causes the computer to execute processing for detecting a position of a center point of a circular pattern, in which a position of a center point of a circular pattern contained in a photographic image is detected from the photographic image,

• wherein the processing for detecting a position of a center point of a circular pattern comprises:
• i) a vote value acquiring process for:
• performing voting of coordinates of all pixels in the photographic image onto a Hough space corresponding to annuluses, which Hough space is defined by a coordinate system having an X coordinate axis for a center point of a circle, a Y coordinate axis for a center point of a circle, and an r coordinate axis for a radial direction, and
• acquiring a vote value of each of voting positions having coordinates (X, Y, r) on the Hough space from a calculation of a number of votes having been given to each of the voting positions having the coordinates (X, Y, r) on the Hough space, the thus acquired vote value being taken as a first integrated vote value, a plurality of first integrated vote values being obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, and
• ii) a center position detecting process for detecting a position, which is represented by (X, Y) coordinate values of a voting position associated with the largest first integrated vote value among the plurality of the first integrated vote values having been obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, as the position of the center point of the circular patterns
• wherein weighted addition is performed on the number of votes having been given by all of the pixels in the photographic image, and wherein the number of a vote given by a pixel having a high chromatic color degree is assigned with a weight lighter than the weight assigned to the number of a vote given by a pixel having a low chromatic color degree, and
• a value having been obtained from the weighted addition is taken as the vote value.

A computer recording medium storing a program which, when executed by a computer, causes the computer to execute processing for detecting a position of a center point of a circular pattern, in which a position of a center point of a circular pattern contained in a photographic image is detected from the photographic image,

• wherein the processing for detecting a position of a center point of a circular pattern comprises:
• i) a vote value acquiring process for:
• performing voting of coordinates of all pixels in the photographic image onto a Hough space corresponding to annuluses, which Hough space is defined by a coordinate system having an X coordinate axis for a center point of a circle, a Y coordinate axis for a center point of a circle, and an r coordinate axis for a radial direction, and
• acquiring a vote value of each of voting positions having coordinates (X, Y, r) on the Hough space from a calculation of a number of votes having been given to each of the voting positions having the coordinates (X, Y, r) on the Hough space, a plurality of vote values being obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space,
• ii) a vote value integrating process for adding the vote values of voting positions, which have identical (X, Y) coordinate values on the Hough space among the voting positions having the coordinates (X, Y, r) on the Hough space, to one another, a second integrated vote value being obtained from the addition and with respect to the voting positions, which have the identical (X, Y) coordinate values on the Hough space, a plurality of second integrated vote values being obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, and
• iii) a center position detecting process for detecting a position, which is represented by (X, Y) coordinate values corresponding to the largest second integrated vote value among the plurality of the second integrated vote values having been obtained with respect to the voting positions having the coordinates (X, Y, r) on the Hough space, as the position of the center point of the circular pattern,
• wherein weighted addition is performed on the number of votes having been given by all of the pixels in the photographic image, and wherein the number of a vote given by a pixel having a high chromatic color degree is assigned with a weight lighter than the weight assigned to the number of a vote given by a pixel having a low chromatic color degree, and
• a value having been obtained from the weighted addition is taken as the vote value.