image-js/lib/featureMatching/descriptors/getBriefDescriptors.js

Image processing and manipulation in JavaScript

import checkProcessable from '../../utils/validators/checkProcessable.js';
import { compareIntensity } from '../utils/compareIntensity.js';
import { getGaussianPoints } from '../utils/getGaussianPoints.js';
import { getKeypointPatch } from './utils/getKeypointPatch.js';
/**
 * Generate the rBRIEF descriptors for the desired keypoints of an image.
 * The rBRIEF descriptors are presented in these articles:
 * - ORB article: DOI: 10.1109/ICCV.2011.6126544
 * - rBRIEF article: DOI: 10.1007/978-3-642-15561-1_56.
 * @param image - Source image of the keypoints.
 * @param keypoints - Keypoints for which the descriptors are wanted.
 * @param options - Get rotated BRIEF descriptors options.
 * @returns The descriptors for the given keypoints.
 */
export function getBriefDescriptors(image, keypoints, options = {}) {
    const { patchSize = 31, descriptorLength = 256, smoothingOptions = {
        sigma: Math.sqrt(2),
        size: Math.min(image.height, image.width, 9),
    }, pointsDistributionOptions, } = options;
    checkProcessable(image, {
        alpha: false,
        colorModel: 'GREY',
    });
    if (!(patchSize % 2)) {
        throw new TypeError('patchSize must be an odd integer');
    }
    if (Math.min(image.width, image.height) < patchSize) {
        throw new RangeError(`image is too small for patchSize = ${patchSize}`);
    }
    const gaussianPoints = getGaussianPoints(patchSize, patchSize, {
        ...pointsDistributionOptions,
        nbPoints: descriptorLength * 2,
    });
    const smoothed = image.gaussianBlur(smoothingOptions);
    const descriptors = [];
    const filteredKeypoints = [];
    for (const keypoint of keypoints) {
        let patch;
        try {
            patch = getKeypointPatch(smoothed, keypoint, { patchSize });
        }
        catch {
            continue;
        }
        if (patch === null)
            continue;
        const descriptor = new Uint8Array(descriptorLength);
        for (let i = 0; i < descriptorLength; i++) {
            const p1 = gaussianPoints[i];
            const p2 = gaussianPoints[i + descriptorLength];
            descriptor[i] = Number(compareIntensity(patch, p1, p2));
        }
        descriptors.push(descriptor);
        filteredKeypoints.push(keypoint);
    }
    return { keypoints: filteredKeypoints, descriptors };
}
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