US 5,694,487 AGranted

Method and apparatus for determining feature points

AssigneeDaewoo Electronics Co., Ltd.

InventorMin-Sub Lee

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Abstract

A method for determining feature points comprises a step for (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, (d) generating a second edge map having the normalized direction gradients for each pixel, (e) dividing the first edge map into a plurality of blocks of an identical size, (f) providing, for each of the pixels included in each of the blocks, normalized directional gradients for a set of a predetermined number of pixels from the second edge map, (g) obtaining a variance for each of the pixels included in each of the blocks based on the provided normalized directional gradients, (h) determining a feature point for each of the blocks based on the gradient magnitude and variance corresponding to each of the pixels therein.

Claims4

Dependent claims

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).times.(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).times.(N+1) number of second processing blocks, each having normalized directional gradients for (2M+1).times.(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.

7 more elements

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).times.(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).times.(N+1) number of second processing blocks, each having normalized directional gradients for (2M+1).times.(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.

7 more elements

Dependencies are inferred from the claim text.