@thi.ng/pixel-analysis/analyze-features.js

Image color & feature analysis utilities

import {
  convolveImage,
  EDGE5,
  SOBEL_X,
  SOBEL_Y
} from "@thi.ng/pixel-convolve/convolve";
import {} from "@thi.ng/pixel/float";
import { FLOAT_GRAY } from "@thi.ng/pixel/format/float-gray";
import { FLOAT_GRAY_RANGE } from "@thi.ng/pixel/format/float-gray-range";
import { magSq } from "@thi.ng/vectors/magsq";
const { sqrt } = Math;
const FMT_EDGE = FLOAT_GRAY_RANGE(-24, 24);
const FMT_SOBEL = FLOAT_GRAY_RANGE(-4, 4);
const analyzeFeatures = (img) => {
  const { width, height } = img;
  const numPixels = width * height;
  const $img = img.format !== FLOAT_GRAY ? img.as(FLOAT_GRAY) : img;
  const imgEdge = convolveImage($img, { kernel: EDGE5 });
  imgEdge.format = FMT_EDGE;
  const imgSobelX = convolveImage($img, { kernel: SOBEL_X });
  imgSobelX.format = FMT_SOBEL;
  const imgSobelY = convolveImage($img, { kernel: SOBEL_Y });
  imgSobelY.format = FMT_SOBEL;
  const edge = sqrt(magSq(imgEdge.data)) / numPixels;
  const sobX = magSq(imgSobelX.data);
  const sobY = magSq(imgSobelY.data);
  const sobelX = sqrt(sobX) / numPixels;
  const sobelY = sqrt(sobY) / numPixels;
  const sobel = sqrt(sobX + sobY) / numPixels;
  return {
    imgEdge,
    imgSobelX,
    imgSobelY,
    edge,
    sobelX,
    sobelY,
    sobel
  };
};
export {
  analyzeFeatures
};