Method for color transition detection
First Claim
1. A method for selecting colors to detect color transitions, comprising:
- providing an object having at least two colors for which a color transition is to be detected, a first color of the at least two colors defined by a first chrominance coordinate in a color space and a second color of the at least two colors defined by a second chrominance coordinate in the color space;
projecting a line from each respective point defined by the first and second chrominance coordinates to a diameter having a given angle of orientation θ
on a color wheel defined by the color space, the lines being normal to the diameter;
calculating a distance D between respective points where the lines intersect the diameter; and
selecting for detection of color transitions only colors for which the calculated distance D exceeds a predetermined threshold.
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Abstract
A hand-manipulated prop is picked-up via a single video camera, and the camera image is analyzed to isolate the part of the image pertaining to the object for mapping the position and orientation of the object into a three-dimensional space, wherein the three-dimensional description of the object is stored in memory and used for controlling action in a game program, such as rendering of a corresponding virtual object in a scene of a video display. Algorithms for deriving the three-dimensional descriptions for various props employ geometry processing, including area statistics, edge detection and/or color transition localization, to find the position and orientation of the prop from two-dimensional pixel data. Criteria are proposed for the selection of colors of stripes on the props which maximize separation in the two-dimensional chrominance color space, so that instead of detecting absolute colors, significant color transitions are detected. Thus, the need for calibration of the system dependent on lighting conditions which tend to affect apparent colors can be avoided.
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Citations
20 Claims
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1. A method for selecting colors to detect color transitions, comprising:
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providing an object having at least two colors for which a color transition is to be detected, a first color of the at least two colors defined by a first chrominance coordinate in a color space and a second color of the at least two colors defined by a second chrominance coordinate in the color space; projecting a line from each respective point defined by the first and second chrominance coordinates to a diameter having a given angle of orientation θ
on a color wheel defined by the color space, the lines being normal to the diameter;calculating a distance D between respective points where the lines intersect the diameter; and selecting for detection of color transitions only colors for which the calculated distance D exceeds a predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for identifying color pixels in a video image comprising:
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tracking an object of interest against a background, wherein the object of interest has a first color and the background has a second color; detecting the first and second color, wherein each color is represented as a respective color chrominance coordinate in a color wheel in a color space; projecting a line from each respective point defined by the first and second chrominance coordinates to a diameter having a given angle of orientation θ
on the color wheel defined by the color space, the lines being normal to the diameter;calculating a distance D between respective points where the lines intersect the diameter; and identifying those pixels wherein the calculated distance D exceeds a predetermined threshold. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A computer-readable medium encoded with a computer program and executable by a computer comprising:
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tracking an object of interest against a background, wherein the object of interest has a first color and the background has a second color; detecting the first and second color, wherein each color is represented as a respective color chrominance coordinate in a color wheel in a color space; projecting a line from each respective point defined by the first and second chrominance coordinates to a diameter having a given angle of orientation θ
on the color wheel defined by the color space, the lines being normal to the diameter;calculating a distance D between respective points where the lines intersect the diameter; and identifying those pixels wherein the calculated distance D exceeds a predetermined threshold. - View Dependent Claims (18, 19, 20)
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Specification