Method and system for detecting diagonal strength of an edge in an image

• US 20050168654A1
• Filed: 09/21/2004
• Published: 08/04/2005
• Est. Priority Date: 01/30/2004
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Law, Patrick, Neuman, Darren
• Granted Patent: US 7,519,232 B2
• Time in Patent Office: Days
• US Class Current: 348/700
• CPC Class Codes: H04N 5/142 Edging; Contouring

Abstract

A system and method that determines the strength of an edge in a video image using a gradient of the edge in a first direction and a gradient of the edge in a second direction. The system uses the gradient in the first direction and the gradient in the second direction to approximate a distance function to determine the strength of the edge. A programmable threshold may be used in the determination, where an edge is treated like it does not exist if the distance is less than the threshold. The distance function may be an approximation of the Cartesian distance function.

Claims

1. A system that determines the strength of an edge in a video image, the system comprising:

a first processing circuitry that determines a gradient of the edge in a first direction;

a second processing circuitry that determines a gradient of the edge in a second direction;

a first circuitry that approximates a distance function using the gradient in the first direction and the gradient in the second direction;

a second circuitry that compares the distance to a threshold; and

wherein the strength of the edge is determined based on a result of the comparison.

2. The system according to claim 1 wherein the threshold is programmable.

3. The system according to claim 1 wherein the edge is ignored when the distance is less than the threshold.

4. The system according to claim 1 wherein the first processing circuitry comprises a vertical edge detector.

5. The system according to claim 1 wherein the second processing circuitry comprises a horizontal edge detector.

6. The system according to claim 1 wherein the first circuitry comprises a distance approximation block.

7. The system according to claim 1 wherein the second circuitry comprises a threshold block.

8. A method that determines the strength of an edge in a video image, the method comprising:

determining a gradient of the edge in a first direction;

determining a gradient of the edge in a second direction;

approximating the distance function using the gradient in the first direction and the gradient in the second direction;

comparing the distance to a threshold; and

determining the strength of the edge based on the result of the comparison.

9. The method according to claim 8 wherein the threshold is programmable.

10. The method according to claim 8 further comprising ignoring the edge when the distance is less than the threshold.

11. The method according to claim 8 wherein the first direction is a horizontal direction.

12. The method according to claim 8 wherein the second direction is a vertical direction.

13. The method according to claim 8 wherein the approximated distance is an approximated Cartesian distance.

14. A machine-readable storage having stored thereon, a computer program having at least one code section that determines the strength of an edge in a video image, the at least one code section being executable by a machine for causing the machine to perform steps comprising:

determining a gradient of the edge in a first direction;

determining a gradient of the edge in a second direction;

approximating the distance function using the gradient in the first direction and the gradient in the second direction;

comparing the distance to a threshold; and

determining the strength of the edge based on the result of the comparison.

15. The machine-readable storage according to claim 14 wherein the threshold is programmable.

16. The machine-readable storage according to claim 14 further comprising code for ignoring the edge when the distance is less than the threshold.

17. The machine-readable storage according to claim 14 wherein the first direction is a horizontal direction.

18. The machine-readable storage according to claim 14 wherein the second direction is a vertical direction.

19. The machine-readable storage according to claim 14 wherein the approximated distance is an approximated Cartesian distance.

20. A method that approximates the Cartesian distance of a point from an origin of a plane in which the point lies, the method comprising:

determining a first coordinate of the point in a first direction;

determining a second coordinate of the point in a second direction;

determining a maximum of the absolute value of the first coordinate and the absolute value of the second coordinate;

determining a minimum of the absolute value of the first coordinate and the absolute value of the second coordinate; and

using the maximum and the minimum to approximate the Cartesian distance function of the point from the origin.