@thi.ng/tensors/kernels.js

0D/1D/2D/3D/4D tensors with extensible polymorphic operations and customizable storage

import { identity } from "@thi.ng/api/fn";
import { constant, tensor } from "./tensor.js";
const SOBEL1 = tensor([-1, 0, 1]);
const SOBEL2 = tensor([
  [-1, -2, -1],
  [0, 0, 0],
  [1, 2, 1]
]);
const SOBEL3 = tensor([
  [
    [-1, -2, -1],
    [-2, -4, -2],
    [-1, -2, -1]
  ],
  [
    [0, 0, 0],
    [0, 0, 0],
    [0, 0, 0]
  ],
  [
    [1, 2, 1],
    [2, 4, 2],
    [1, 2, 1]
  ]
]);
const EDGE2 = (r) => {
  r |= 0;
  const w = 2 * r + 1;
  const data = new Array(w * w).fill(-1);
  data[data.length >> 1] = w * w - 1;
  return tensor("num", [w, w], { data, copy: false });
};
const SHARPEN2_3x3 = tensor([
  [0, -1, 0],
  [-1, 5, -1],
  [0, -1, 0]
]);
const BOX_BLUR2 = (r) => {
  r = 2 * r + 1;
  return constant([r, r], 1 / (r * r), "num");
};
const GAUSSIAN_BLUR2 = (r) => {
  r |= 0;
  const sigma = -1 / (2 * (Math.SQRT2 * r / 3) ** 2);
  const res = [];
  let sum = 0;
  for (let y = -r; y <= r; y++) {
    for (let x = -r; x <= r; x++) {
      const g = Math.exp((x * x + y * y) * sigma);
      res.push(g);
      sum += g;
    }
  }
  const size = r * 2 + 1;
  return tensor("num", [size, size], {
    data: res.map((x) => x / sum),
    copy: false
  });
};
const { max, min } = Math;
const MAX2_POOL = (w, h = w) => {
  return {
    shape: [w, h],
    init: () => -Infinity,
    reduce: (acc, val) => max(acc, val),
    complete: identity
  };
};
const MIN2_POOL = (w, h = w) => {
  return {
    shape: [w, h],
    init: () => Infinity,
    reduce: (acc, val) => min(acc, val),
    complete: identity
  };
};
const MAXIMA2 = (r) => {
  r |= 0;
  const w = 2 * r + 1;
  return {
    shape: [w, w],
    init: () => [-Infinity, 0],
    reduce: (acc, val, i, j) => {
      if (i === r && j === r) acc[1] = val;
      else acc[0] = max(acc[0], val);
      return acc;
    },
    complete: (acc) => acc[1] > acc[0] ? 1 : 0
  };
};
const MINIMA2 = (r) => {
  r |= 0;
  const w = 2 * r + 1;
  return {
    shape: [w, w],
    init: () => [Infinity, 0],
    reduce: (acc, val, i, j) => {
      if (i === r && j === r) acc[1] = val;
      else acc[0] = min(acc[0], val);
      return acc;
    },
    complete: (acc) => acc[1] < acc[0] ? 1 : 0
  };
};
export {
  BOX_BLUR2,
  EDGE2,
  GAUSSIAN_BLUR2,
  MAX2_POOL,
  MAXIMA2,
  MIN2_POOL,
  MINIMA2,
  SHARPEN2_3x3,
  SOBEL1,
  SOBEL2,
  SOBEL3
};