import { getPixels, savePixels } from 'ndarray-pixels';

const bytesIn = await fetch('./input.png')
    .then((res) => res.arrayBuffer())
    .then((arrayBuffer) => new Uint8Array(arrayBuffer));

// read
const pixels = await getPixels(bytesIn, 'image/png'); // Uint8Array -> ndarray

// modify
for (let i = 0; i < pixels.shape[0]; ++i) {
  for (let j = 0; j < pixels.shape[1]; ++j) {
    pixels.set(i, j, 255);
  }
}

// write
const bytesOut = await savePixels(pixels, 'image/png'); // ndarray -> Uint8Array

const fs = require('fs');
const { getPixels, savePixels } = require('ndarray-pixels');

const bufferIn = fs.readFileSync('./input.png');

// read
const pixels = await getPixels(bufferIn, 'image/png'); // Uint8Array -> ndarray

// modify
for (let i = 0; i < pixels.shape[0]; ++i) {
  for (let j = 0; j < pixels.shape[1]; ++j) {
    pixels.set(i, j, 255);
  }
}

// write
const bufferOut = await savePixels(pixels, 'image/png'); // ndarray -> Uint8Array
fs.writeFileSync('./output.png', bufferOut);