Image processing device, image processing method and image processing system

An image processing method using an image processing device that calculates, from a moving image of a subject performing a swing motion of a club taken by a single image acquisition device, position coordinates in an image plane of the moving image in real space, wherein

• the method includes:
• identifying positions of two reference points and a position of physical characteristic point of the subject in the moving image,
• obtaining an angle of a line segment connecting the two reference points with respect to the image plane,
• calculating a conversion ratio indicating a ratio between the length in the moving image and the length in the real space, based on the distance between the two reference points in the moving image, the obtained angle, and the distance between the two reference points in the real space, and
• calculating position coordinates of at least one of:
• the two reference points and the physical characteristic point of the subject in the image plane in the real space, based on the calculated conversion ratio and at least one of:
• the identified positions of the two reference points and the identified position of the physical characteristic point of the subject.

An image processing system comprising a single image acquisition device that takes a subject performing a swing motion of a club, and an image processing device that calculates, from a moving image taken by the single image acquisition device, position coordinates in an image plane of the moving image in real space, wherein

• the image processing device comprises:
• a processor, and the processor is configured to:
• identify positions of two reference points and a position of physical characteristic point of the subject in the moving image,
• obtain an angle of a line segment connecting the two reference points with respect to the image plane,
• calculate a conversion ratio indicating a ratio between the length in the moving image and the length in the real space, based on the distance between the two reference points in the moving image, the obtained angle, and the distance between the two reference points in the real space, and
• calculate position coordinates of at least one of:
• the two reference points and the physical characteristic point of the subject in the image plane in the real space, based on the calculated conversion ratio and at least one of:
• the identified positions of the two reference points and the identified position of the physical characteristic point of the subject.