Head detecting apparatus, head detecting method, and head detecting program

A head detecting method comprising:

• a foreground extracting step for extracting a foreground region, in which a person has been taken, from an input image;
• a first main axis computing step for computing a main axis of the foreground region;
• a head region computing step for computing a head region included in the foreground region as a part thereof, based on the main axis of the foreground region and a shape of the foreground region;
• an ellipse determining step for determining an ellipse to be applied to the head of the person, based on a shape of the head region;
• a search step for searching a top point of a head of a person, by setting a starting point at one of intersecting points of the outline of the foreground region and the main axis, which is deemed to be at a higher position in the image pick-up target space, and following pixels of the outline in the foreground region;
• and
• a circle computing step for computing a circle, in which the proportion of pixels of the foreground region included in the circle is equal to or greater than a predetermined reference proportion, as a circle surrounding the head, among circles which have centers on a line connecting the top point and the center of gravity of the foreground region and pass through the top point of the head;
• wherein the foreground region included in the circle surrounding the head is calculated as the head region.

A head detecting method comprising the steps of:

• a foreground extracting step for extracting a foreground region, in which a person has been taken, from an input image;
• a first main axis computing step for computing a main axis of the foreground region;
• a head region computing step for computing a head region included in the foreground region as a part thereof, based on the main axis of the foreground region and a shape of the foreground region;
• and
• an ellipse determining step for determining an ellipse to be applied to the head of the person, based on a shape of the head region, wherein
• the ellipse detection step includes a second principal computing step for computing a main axis of the head region, and determining the ellipse having the main axis as a long axis and wherein
• the second main axis computing step includes:
• a second moment computing step for computing a moment around a center of gravity of the head region;
• a second orthogonal axes computing step for computing two orthogonal axes in the head region based on the moment around the center of gravity of the head region;
• and
• a second main axis selection step for selecting an axis which forms smaller angle with the main axis of the foreground region, in the two orthogonal axes.

A head detecting method comprising the steps of:

• a foreground extracting step for extracting a foreground region, in which a person has been taken, from an input image;
• a first main axis computing step for computing a main axis of the foreground region;
• a head region computing step for computing a head region included in the foreground region as a part thereof, based on the main axis of the foreground region and a shape of the foreground region;
• and
• an ellipse determining step for determining an ellipse to be applied to the head of the person, based on a shape of the head region, wherein:
• the ellipse detection step includes a second principal computing step for computing a main axis of the head region, and determines the ellipse having the main axis as a long axis, a flesh color extraction step for extracting a biggest flesh color area in the head region;
• a short axis determination step for determining a length of the short axis according to a largest distance between the main axis of the head region and pixels in the flesh color area and a long axis determination step for setting a value obtained by multiplying the length of the short axis of the ellipse determined by the short axis determination step by a predetermined value which is larger than 1, as a length of a long axis of the ellipse.

A head detecting method comprising:

• a foreground extracting step for extracting a foreground region, in which a person has been taken, from an input image;
• a first main axis computing step for computing a main axis of the foreground region;
• a head region computing step for computing a head region included in the foreground region as a part thereof, based on the main axis of the foreground region and a shape of the foreground region;
• an ellipse determining step for determining an ellipse to be applied to the head of the person, based on a shape of the head region;
• an input step for inputting a plurality of frame images constituting a moving image as a plurality of the input image;
• and
• a detection step for detecting a change of a position and an orientation of the person's head based on a change of the ellipse determined according to the plurality of frame images, wherein:
• the input step inputs the plurality of the frame images constituting the moving image captured by the image pick-up device for a monitoring purpose;
• and further including:
• a storage step for storing history of the change of the position and the orientation of the person's head for each of a plurality of persons in a storage section;
• and
• an abnormality detection step for detecting an abnormal action of the person under a condition that a difference between an amount of the change of the position and the orientation of the person's head and a reference amount of change based on a position and a change of other person's head stored in the storage section is equal to or more than a predetermined amount.