Method and apparatus for determining feature points

Claim 1

An apparatus, for use in a video signal processor which adopts a feature point based motion compensation technique, for determining feature points, said feature points being pixels capable of representing motions of objects in a video frame, comprising: means for providing directional gradients and a gradient magnitude for each pixel in the video frame; means for normalizing the directional gradients by dividing the directional gradients with the gradient magnitude; means for generating a first edge map having the gradient magnitude for each pixel based on the gradient magnitude for each pixel, wherein the first edge map includes a number of edge points, each having a gradient magnitude, and a multiplicity of non-edge points, each having a zero value; means for generating a second edge map having the normalized directional gradients for each pixel; means for generating a plurality of grid points; means for dividing the first edge map into a plurality of first processing blocks of an identical size, wherein the blocks do not overlap each other and each of the first processing blocks includes (N+1)×(N+1) gradient magnitudes corresponding to the pixels therein and has a grid points at the center thereof, N being an even integer; means for providing, for the pixels included in each of the first processing blocks, (N+1)×(N+1) number of second processing blocks, each having normalized directional gradients for (2M+1)×(2M+1) number of pixels from the second edge map, wherein each of the second processing blocks includes said each of the pixels included in the first processing block at center thereof, M being an odd integer; means for obtaining a variance for each of the pixels included in each of the first processing blocks based on the provided normalized directional gradients for each of the second processing blocks; and means for determining a feature point for each of the first processing blocks based on the gradient magnitude and variance corresponding to each of the pixels therein.

Claim 2

An apparatus, for use in a video signal processor which adopts a feature point based motion compensation technique, for determining feature points, said feature points being pixels capable of representing motions of objects in a video frame, comprising: means for providing directional gradients and a gradient magnitude for each pixel in the video frame; means for normalizing the directional gradients by dividing the directional gradients with the gradient magnitude; means for generating a first edge map having the gradient magnitude for each pixel based on the gradient magnitude for each pixel, wherein the first edge map includes a number of edge points, each having a gradient magnitude, and a multiplicity of non-edge points, each having a zero value; means for generating a second edge map having the normalized directional gradients for each pixel; means for generating a plurality of grid points; means for dividing the first edge map into a plurality of first processing blocks of an identical size, wherein the blocks do not overlap each other and each of the first processing blocks includes (N+1)×(N+1) gradient magnitudes corresponding to the pixels therein and has a grid points at the center thereof, N being an even integer; means for providing, for the pixels included in each of the first processing blocks, (N+1)×(N+1) number of second processing blocks, each having normalized directional gradients for (2M+1)×(2M+1) number of pixels from the second edge map, wherein each of the second processing blocks includes said each of the pixels included in the first processing block at center thereof, M being an odd integer; means for obtaining a variance for each of the pixels included in each of the first processing blocks based on the provided normalized directional gradients for each of the second processing blocks; and means for determining a feature point for each of the first processing blocks based on the gradient magnitude and variance corresponding to each of the pixels therein.

Claim 4

A method for use in a video signal processor which adopts a feature point based motion compensation technique, for determining feature points, said feature points being pixels capable of representing motions of objects in a video frame, comprising the steps of: (a) providing directional gradients and a gradient magnitude for each pixel in the video frame; (b) normalizing the directional gradients by dividing the directional gradients with the gradient magnitude; (c) generating a first edge map having the gradient magnitude for each pixel based on the gradient magnitude for each pixel, wherein the first edge map includes a number of edge points, each having a gradient magnitude, and a multiplicity of non-edge points, each having a zero value; (d) generating a second edge map having the normalized direction gradients for each pixel; (e) generating a plurality of grid points; (f) dividing the first edge map into a plurality of first processing blocks of an identical size, wherein the blocks do not overlap each other and each of the first processing blocks includes (N+1)×(N+1) gradient magnitudes corresponding to the pixels therein and has a grid points at the center thereof, N being an even integer; (g) providing, for the pixels included in each of the first processing blocks, (N+1)×(N+1) number of second processing blocks, each having normalized directional gradients for (2M+1)×(2M+1) number of pixels from the second edge map, wherein each of the second processing blocks includes said each of the pixels included in the first processing block at center thereof, M being an odd integer; (h) obtaining e variance for each of the pixels included in each of the first processing blocks based on the provided normalized directional gradients for each of the second processing blocks; and (i) determining e feature point for each of the first processing blocks based on the gradient magnitude and variance corresponding to each of the pixels therein.

Claim 5

A method for use in a video signal processor which adopts a feature point based motion compensation technique, for determining feature points, said feature points being pixels capable of representing motions of objects in a video frame, comprising the steps of: (a) providing directional gradients and a gradient magnitude for each pixel in the video frame; (b) normalizing the directional gradients by dividing the directional gradients with the gradient magnitude; (c) generating a first edge map having the gradient magnitude for each pixel based on the gradient magnitude for each pixel, wherein the first edge map includes a number of edge points, each having a gradient magnitude, and a multiplicity of non-edge points, each having a zero value; (d) generating a second edge map having the normalized direction gradients for each pixel; (e) generating a plurality of grid points; (f) dividing the first edge map into a plurality of first processing blocks of an identical size, wherein the blocks do not overlap each other and each of the first processing blocks includes (N+1)×(N+1) gradient magnitudes corresponding to the pixels therein and has a grid points at the center thereof, N being an even integer; (g) providing, for the pixels included in each of the first processing blocks, (N+1)×(N+1) number of second processing blocks, each having normalized directional gradients for (2M+1)×(2M+1) number of pixels from the second edge map, wherein each of the second processing blocks includes said each of the pixels included in the first processing block at center thereof, M being an odd integer; (h) obtaining e variance for each of the pixels included in each of the first processing blocks based on the provided normalized directional gradients for each of the second processing blocks; and (i) determining e feature point for each of the first processing blocks based on the gradient magnitude and variance corresponding to each of the pixels therein.