IMAGING DEVICE AND IMAGE ANALYSIS METHOD

• US 20130038718A1
• Filed: 08/02/2012
• Published: 02/14/2013
• Est. Priority Date: 08/08/2011
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: NAKAGOME, Kouichi
• Granted Patent: US 8,704,888 B2
• Time in Patent Office: Days
• US Class Current: 348/135
• CPC Class Codes: G06T 2207/30204 Marker
• CPC Class Codes: G06T 2207/30221 Sports video; Sports image
• CPC Class Codes: G06T 2207/30224 Ball; Puck
• CPC Class Codes: G06T 2207/30241 Trajectory
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS

Abstract

An imaging device includes a separability calculating portion for calculating a separability of a frame image by filtering the frame image containing a ball image elliptically deformed using an ellipse separability filter having an inside region and an outside region located outside of the inside region, an estimating portion for estimating a set of a center position, major axis, minor axis and inclination angle of the inside region, the set resulting in a maximum separability by changing the center position, major axis, minor axis and inclination angle of the inside region, as a set of a center position, major axis, minor axis and inclination angle of the ball image, and a speed calculating portion for calculating a speed of the ball based on a difference between the center positions of the ball images estimated by the estimating portion, a number of frames between the frame images and a frame rate.

Claims

1. An imaging device comprising:

an image pickup portion of a rolling shutter system,

an image pickup controlling portion for controlling the image pickup portion so as to pickup at least two frame images by continuous image capturing, each of the images containing a ball image elliptically deformed,

a separability calculating portion for calculating a separability of pixels between an inside region and an outside region by filtering the frame images captured by the image pickup controlling portion using an ellipse separability filter having the inside region of an ellipse shape whose major axis is inclined with respect to a horizontal line and the outside region that is adjacent to the inside region,

an estimating portion for estimating a set of a center position, major axis, minor axis and inclination angle of the elliptical inside region, the set resulting in a maximum separability by changing the center position, major axis, minor axis and inclination angle of the inside region, as a set of a center position, major axis, minor axis and inclination angle of the ball image, and

a state value calculating portion for calculating a moving-state value of the ball based on the each value of the center position, major axis, minor axis or inclination angle, estimated by the estimating portion, of the ball images in the at least two frame images.

2. The imaging device of claim 1, wherein

the state value calculating portion comprises a speed calculating portion for calculating a speed of the ball based on a difference between the center positions of the ball images in the at least two frame images estimated by the estimating portion, a number of frames between the frame images and a frame rate.

3. The imaging device of claim 1, wherein

the state value calculating portion comprises a vertical take-off angle calculating portion for calculating a take-off angle of the ball in an upward or downward direction with respect to a horizontal plane based on a difference between the center positions of the ball images in the at least two frame images estimated by the estimating portion.

4. The imaging device of claim 1, wherein

the state value calculating portion comprises a horizontal take-off angle calculating portion for calculating a take-off angle of the ball in a right or left direction with respect to a plane orthogonal to an image pickup direction of the image pickup portion based on a major axis or minor axis of the ball image in the at least two frame images estimated by the estimating portion, a horizontal view angle of the image pickup portion, a center coordinates of the frame image and a number of vertical lines of the frame image.

5. The imaging device of claim 1, wherein

the estimating portion estimates a set of a center position, major axis and minor axis that results in a maximum separability, being obtained by the separability calculating portion by changing the center position, major axis and minor axis of the inside region while the inclination angle of the inside region is maintained, as a set of a center position, major axis and minor axis of the ball image, and estimates an inclination angle that results in a maximum separability, being obtained by the separability calculating portion by changing the inclination angle of the inside region while the center position, major axis and minor axis of the inside region are maintained, as an inclination angle of the ball image.

6. The imaging device of claim 1, further comprising:

a deviation amount calculating portion for calculating a deviation, caused by a rolling shutter, in a horizontal direction between adjacent horizontal lines based on a horizontal difference of center positions, estimated by the estimating portion, between the frame images,

a deformation correction portion for correcting the deformed ball image in the frame image into a circle based on the deviation amount,

a coordinate transforming portion for coordinates-converting the ball image corrected by the deformation correction portion onto a surface of a three-dimensional spherical model,

a rotation angle estimating portion for estimating a rotation angle of the ball image between the frame images that are coordinates-converted by the coordinate transforming portion, and

a spin speed calculating portion for calculating a spin speed of the ball based on the rotation angle estimated by the rotation angle estimating portion and the frame rate.

7. An imaging device comprising:

an image pickup portion of a rolling shutter system, an image pickup controlling portion for controlling the image pickup portion so as to pickup a frame image by an image capturing, the frame image containing a ball image elliptically deformed,

a separability calculating portion for calculating a separability of pixels between an inside region and an outside region by filtering the frame image captured by the image pickup controlling portion using an ellipse separability filter having the inside region of an ellipse shape whose major axis is inclined with respect to a horizontal line and the outside region located adjacently and concentrically outside the inside region,

an estimating portion for estimating a set of a center position, major axis, minor axis and inclination angle of the elliptical inside region, the set resulting in a maximum separability by changing the center position, major axis, minor axis and inclination angle of the inside region, as a set of a center position, major axis, minor axis and inclination angle of the ball image,

a first intersection calculating portion for calculating positions of tangent points of an ellipse defined by the center position, major axis, minor axis and inclination angle estimated by the estimating portion with two parallel tangent lines that are in contact with the ellipse,

a second intersection calculating portion for calculating an intersection point between the ellipse and a horizontal line that passes through the center position of the ellipse estimated by the estimating portion, and

a speed calculating portion for calculating a speed of the ball based on the positions of the tangent points and the intersection points calculated by the first and the second intersection calculating portions, a delay time between horizontal lines of a rolling shutter of the image pickup portion and an actual size of the ball.

8. A method of image analysis comprising:

calculating a separability of pixels, for at least two frame images each image being continuously captured by an image pickup portion with a rolling shutter system and thus containing a moving ball image elliptically deformed, between an inside region and an outside region by filtering the frame images using an ellipse separability filter having the inside region of an ellipse shape whose major axis is inclined with respect to a horizontal line and the outside region that is adjacent to the inside region,

estimating a set of a center position, major axis, minor axis and inclination angle of the inside region, the set resulting in a maximum separability obtained in the separability calculating step by changing the center position, major axis, minor axis and inclination angle of the inside region, as a set of a center position, major axis, minor axis and inclination angle of the ball image, and

calculating a moving-state value of the ball based on the each value of the center position, major axis, minor axis and inclination angle, estimated in the estimating step, of the ball image in the at least two frame images.

9. A method of image analysis comprising:

calculating a separability of pixels, for a frame image being captured by an image pickup portion with a rolling shutter system and thus containing a moving ball image elliptically deformed, between an inside region and an outside region by filtering the frame image using an ellipse separability filter having the inside region of an ellipse shape whose major axis is inclined with respect to a horizontal line and the outside region located adjacently and concentrically outside the inside region,

estimating a set of a center position, major axis, minor axis and inclination angle, the set resulting in a maximum separability obtained in the separability calculating step by changing the center position, major axis, minor axis and inclination angle, as a set of a center position, major axis, minor axis and inclination angle of the ball image,

calculating tangent points (first intersection points) of an ellipse defined by the center position, major axis, minor axis and inclination angle estimated by the estimating step with two parallel tangent lines that are in contact with the ellipse,

calculating intersection points (second intersection points) between the ellipse and a horizontal line that passes through the center position of the ellipse estimated by the estimating step, and

calculating a speed of the ball based on the position of the tangent point and the intersection point calculated by the calculating steps for the tangent point and the intersection point, a delay time between horizontal lines of a rolling shutter of the image pickup portion and an actual size of the ball.