@webarkit/jsfeat-next/dist/src/yape/yape.js

Typescript version of jsfeat for WebARKit

import { third_check, is_local_maxima, perform_one_point, lev_table_t } from "./yape_utils";
export class yape {
    level_tables;
    tau;
    constructor() {
        this.level_tables = [];
        this.tau = 7;
    }
    init(width, height, radius, pyramid_levels = 1) {
        radius = Math.min(radius, 7);
        radius = Math.max(radius, 3);
        for (let i = 0; i < pyramid_levels; ++i) {
            this.level_tables[i] = new lev_table_t(width >> i, height >> i, radius);
        }
    }
    detect(src, points, border = 4) {
        const t = this.level_tables[0];
        const R = t.radius | 0, Rm1 = (R - 1) | 0;
        const dirs = t.dirs;
        const dirs_count = t.dirs_count | 0;
        const opposite = dirs_count >> 1;
        const img = src.data, w = src.cols | 0, h = src.rows | 0, hw = w >> 1;
        const scores = t.scores;
        let x = 0, y = 0, row = 0, rowx = 0, ip = 0, im = 0, abs_score = 0, score = 0;
        const tau = this.tau | 0;
        let number_of_points = 0, pt;
        const sx = Math.max(R + 1, border) | 0;
        const sy = Math.max(R + 1, border) | 0;
        const ex = Math.min(w - R - 2, w - border) | 0;
        const ey = Math.min(h - R - 2, h - border) | 0;
        row = (sy * w + sx) | 0;
        for (y = sy; y < ey; ++y, row += w) {
            for (x = sx, rowx = row; x < ex; ++x, ++rowx) {
                (ip = img[rowx] + tau), (im = img[rowx] - tau);
                if (im < img[rowx + R] && img[rowx + R] < ip && im < img[rowx - R] && img[rowx - R] < ip) {
                    scores[rowx] = 0;
                }
                else {
                    perform_one_point(img, rowx, scores, im, ip, dirs, opposite, dirs_count);
                }
            }
        }
        row = (sy * w + sx) | 0;
        for (y = sy; y < ey; ++y, row += w) {
            for (x = sx, rowx = row; x < ex; ++x, ++rowx) {
                score = scores[rowx];
                abs_score = Math.abs(score);
                if (abs_score < 5) {
                    ++x, ++rowx;
                }
                else {
                    if (third_check(scores, rowx, w) >= 3 && is_local_maxima(scores, rowx, score, hw, R)) {
                        pt = points[number_of_points];
                        (pt.x = x), (pt.y = y), (pt.score = abs_score);
                        ++number_of_points;
                        (x += Rm1), (rowx += Rm1);
                    }
                }
            }
        }
        return number_of_points;
    }
}
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