image-js/src/image/operator/convolutionSeparable.js

Image processing and manipulation in JavaScript

import { directConvolution } from 'ml-convolution';

export default function convolutionSeparable(
  data,
  separatedKernel,
  width,
  height,
) {
  const result = new Array(data.length);
  let tmp, conv, offset, kernel;

  kernel = separatedKernel[1];
  offset = (kernel.length - 1) / 2;
  conv = new Array(width + kernel.length - 1);
  tmp = new Array(width);
  for (let y = 0; y < height; y++) {
    for (let x = 0; x < width; x++) {
      tmp[x] = data[y * width + x];
    }
    directConvolution(tmp, kernel, conv);
    for (let x = 0; x < width; x++) {
      result[y * width + x] = conv[offset + x];
    }
  }

  kernel = separatedKernel[0];
  offset = (kernel.length - 1) / 2;
  conv = new Array(height + kernel.length - 1);
  tmp = new Array(height);
  for (let x = 0; x < width; x++) {
    for (let y = 0; y < height; y++) {
      tmp[y] = result[y * width + x];
    }
    directConvolution(tmp, kernel, conv);
    for (let y = 0; y < height; y++) {
      result[y * width + x] = conv[offset + y];
    }
  }
  return result;
}