Method and system for interpolator direction selection during edge detection
View Patent ↗A system and method that determines the direction 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 sign of the product of the gradient in the first direction and the gradient in the second direction along with a ratio of multiples of the two gradients to determine the direction of the edge. The direction may correspond to an angle range, where the ratio of the gradients corresponds to a trigonometric function of the angle of the edge.
1. A system that determines the direction 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 determines the sign of the product of the gradient in the first direction and the gradient in the second direction;
a second circuitry that compares a multiple of the gradient in the first direction to a multiple of the gradient in the second direction; and
wherein the direction of the edge is determined based on the result of the comparison.
2. The system according to claim 1 wherein the direction corresponds to one of a plurality of angle ranges.
3. The system according to claim 2 wherein the ratio of the gradient in the first direction and the gradient in the second direction corresponds to a trigonometric function of an angle in the angle range.
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 multiplier.
7. The system according to claim 1 wherein the second circuitry comprises a comparison block.
8. The system of claim 1 , further comprising:
computing a spatial average, based at least in part on the direction of the edge.
9. The system of claim 1 , further comprising:
selecting one of a plurality of filters, based at least in part on the direction of the edge;
calculating a diagonal strength factor from at least the gradient in the first direction and the gradient in the second direction; and
blending the selected one of the plurality of filters with another one of the plurality of filters based at least in part on the diagonal strength factor.
10. A method that determines the direction 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;
determining the sign of the product of the gradient in the first direction and the gradient in the second direction;
comparing a multiple of the gradient in the first direction to a multiple of the gradient in the second direction; and
determining the direction of the edge based on the result of the comparison.
11. The method according to claim 10 wherein the direction corresponds to one of a plurality of angle ranges.
12. The method according to claim 11 wherein the ratio of the gradient in the first direction and the gradient in the second direction corresponds to a trigonometric function of an angle in the angle range.
13. The method according to claim 10 wherein the first direction is a horizontal direction.
14. The method according to claim 10 wherein the second direction is a vertical direction.
15. A machine-readable storage having stored thereon, a computer program having at least one code section that determines the direction 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;
determining the sign of the product of the gradient in the first direction and the gradient in the second direction;
comparing a multiple of the gradient in the first direction to a multiple of the gradient in the second direction; and
determining the direction of the edge based on the result of the comparison.
16. The machine-readable storage according to claim 15 wherein the direction corresponds to one of a plurality of angle ranges.
17. The machine-readable storage according to claim 16 wherein the ratio of the gradient in the first direction and the gradient in the second direction corresponds to a trigonometric function of an angle in the angle range.
18. The machine-readable storage according to claim 15 wherein the first direction is a horizontal direction.
19. The machine-readable storage according to claim 15 wherein the second direction is a vertical direction.