Method and apparatus for determining the location of a reflective object within a video field

• US 6,549,659 B1
• Filed: 10/09/1996
• Issued: 04/15/2003
• Est. Priority Date: 09/08/1994
• Status: Expired due to Fees

• Current Assignee: WSI Incorporated
• Original Assignee: Andrew Welch
• Inventors: Schaem, Stephan, Welch, Andrew
• Primary Examiner(s): COUSO, YON JUNG
• Application Number:
  US08/731,122
• Time in Patent Office: 2,379 Days
• Field of Search: 382/203, 382/165, 382/199, 382/282, 395/135, 348/586, 358/538, 358/540
• US Class Current: 382/203
• CPC Class Codes: G06T 11/60 Editing figures and text; Combining figures or text
• CPC Class Codes: G06T 7/74 involving reference images or patches
• CPC Class Codes: G06V 10/24 Aligning, centring, orientation detection or correction of the image

Abstract

A system and method for detecting the precise location of a reflective element in a video field wherein the determined location is subsequently utilized to generate a graphic to be added to a foreground video scene utilizing compositing techniques. A signal is generated specifying a precise point in the foreground video scene identifying a position of a reflective element. The signal is derived by comparing objects within the video field with a user specified size, shape and color. Graphics can be repositioned or lines or other graphic elements can be generated which track the movement of the reflective element.

Claims

1. A system for creating a composite video signal having a background portion and a foreground portion, said foreground portion representing a foreground scene containing a moving reflective object having a predetermined color and size, said foreground portion defined by a field of video information provided by a video source having red, blue and green components, said red, blue and green components having been converted to a digital representation, said system comprising:

a) color comparison means for comparing the component of said red, blue, and green video signal, corresponding to the color of said reflective object, to predefined minimum and maximum red, green and blue values, and generating a first signal representing the results of said comparison;

b) means for computing the size and shape of an object within a video field, by scanning in left, right, top, and bottom directions for pixels having a predefined color;

c) size and shape comparison means for comparing the size and shape of said pixels having said predefined color to a predefined size and shape and generating a second signal representing the results of the comparison;

d) means for specifying the relative position of said reflective object within said video field when said first and second signals indicate that the pixels match the predefined color, size and shape;

e) means for supplying the specified relative position to a graphics computer which uses the supplied position to generate a computer generated graphical image represented by signals which are added to said background portion in real time for displaying the graphical image at the specified relative position on a display device such that the graphical image tracks the movement of said reflective object as it moves in said video field.

2. The system defined by claim 1 wherein said color comparison means comprises:

a) a buffer containing said digitized red, green and blue components;

b) a memory containing predetermined minimum and maximum red, green and blue values defining the color of an object to be tracked; and

c) a digital signal processor coupled to said buffer and said memory, said digital signal processor executing a program which obtains red, green and blue values of pixels corresponding to said digitized red, green and blue components and compares the obtained values of said pixels with predetermined minimum and maximum red, green and blue values to determine whether said pixels correspond to a color within the range of said predetermined minimum and maximum red, green an blue values defined for said reflective object.

3. The system defined by claim 1 wherein said means for computing the size and shape of said object comprises:

a) a buffer containing said digitized red, green and blue components;

b) a memory containing predetermined minimum and maximum red, green and blue values defining the color of an object to be tracked;

c) a digital signal processor coupled to said buffer and said memory, said digital signal processor executing a program which obtains red, green and blue values of pixels corresponding to said digitized red, green and blue components and compares the obtained values of said pixels with predetermined minimum and maximum red, green and blue values and calculates left, right, top and bottom borders of the reflective object within said video field by searching said video field to the left, right, top, and bottom of a starting pixel for pixels having a predetermined color.

7. The system defined in claim 3 wherein the relative position of said object corresponds to a position of said starting pixel within said video field.

4. A method for creating a composite video signal having a background portion and a foreground portion, said foreground portion representing a foreground scene containing a moving reflective object having a predetermined color and size, said foreground portion defined by a field of video information provided by a video source having red, blue and green components, said red, blue and green components, having been converted to a digital representation, said method comprising the steps of:

a) comparing the component of a said video signal corresponding to the color of said reflective object to a predefined color generating a first signal representing the results of said comparison;

b) computing the size and shape of an object within a video field, by scanning in left, right, top, and bottom directions for pixels having a predefined color;

c) comparing the size and shape of said pixels having said predefined color within said video field to a predefined size and shape and generating a second signal representing the results of the comparison;

d) specifying the relative position of said reflective object within said video field when said first and second signals indicate that the pixels match the predefined color, size and shape; and

e) supplying the specified relative position to a graphics computer which generates an image signal to be added to said background portion in real time for displaying a graphical image at the specified relative position on a display device such that the graphical image tracks the movement of said reflective object as it moves in said video field.

5. The method defined by claim 4 wherein said color comparison step comprises the steps of:

a) storing said digitized red, green and blue components in a buffer;

b) storing in a memory predetermined minimum and maximum red, green an blue values defining the color of an object to be tracked;

c) obtaining red, green and blue values of pixels corresponding to said digitized red, green and blue components and compares the obtained values of said pixels with predetermined minimum and maximum red, green an blue values to determine whether said pixels correspond to a color within the range of said predetermined minimum and maximum red, green an blue values defined for said reflective object.

6. The method defined by claim 4 wherein said size and shape calculation step comprises the steps:

a) storing said digitized red, green and blue components in a buffer;

b) storing in a memory predetermined minimum and maximum red, green an blue values defining the color of an object to be tracked;

c) obtaining red, green and blue values of pixels corresponding to said digitized red, green and blue components and comparing the obtained values of said pixels with predetermined minimum and maximum red, green an blue values; and

d) calculating left, right, top and bottom borders of the reflective object within said video field by searching said video field to the left, right, top, and bottom of a starting pixel for pixels having a predetermined color.

8. The method defined in claim 6 wherein the specified relative position of said object corresponds to a position of said starting pixel within said video field.