image-js/lib/featureMatching/keypoints/getPatchIntensityMoment.js

Image processing and manipulation in JavaScript

import { getFilledCirclePoints } from '../../utils/geometry/getCirclePoints.js';
import { checkBorderDistance } from '../utils/checkBorderDistance.js';
/**
 * Compute the pq order intensity moment of the circular patch with given radius in the image,
 * relatively to the origin defined in the options.
 * Original article: {@link https://doi.org/10.1006/cviu.1998.0719}.
 * @see {@link https://en.wikipedia.org/wiki/Image_moment}
 * @param image - Image to process.
 * @param p - Order along x.
 * @param q - Order along y.
 * @param options - Get intensity moment options.
 * @returns The intensity moment of order pq of the circular window relative to the center.
 */
export function getPatchIntensityMoment(image, p, q, options = {}) {
    const { center: origin = image.getCoordinates('center'), radius = 3 } = options;
    if (!checkBorderDistance(image, origin, radius)) {
        throw new RangeError(`desired patch is too close to image border`);
    }
    const moment = new Array(image.channels).fill(0);
    const relativeCirclePoints = getFilledCirclePoints(radius);
    for (const point of relativeCirclePoints) {
        for (let channel = 0; channel < image.channels; channel++) {
            const intensity = image.getValue(point.column + origin.column, point.row + origin.row, channel);
            moment[channel] += point.column ** p * point.row ** q * intensity;
        }
    }
    return moment;
}
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