let workingString = "Lorem ipso fuck my hair's on fire";

​

​

function preload()

{

  img = loadImage("DeleteSoon.png");

}

​

​

function setup()

{

  createCanvas(img.width, img.height);

  Encode();

  Decode();

}

​

​

function Encode()

{

  img.loadPixels();

  EncodeString(workingString, img.pixels);

  img.updatePixels();

  image(img, 0, 0);

  // saveCanvas();

}

​

​

function Decode()

{

  img.loadPixels();

  workingString = DecodeImage(img.pixels);

  print(workingString);

  image(img, 0, 0);

}

​

​

function EncodeString(s, pixelArray)

{

  let outOfRoom = false;

  for (let i = 0; i < s.length && 2 * 4 * (i + 1) < pixelArray.length; ++i)

  {

    let code = s.charCodeAt(i);

    let loPixelIndex = 2 * 4 * (i + 0);

    let hiPixelIndex = 2 * 4 * (i + 1);

    EncodeCharacter(code, pixelArray, loPixelIndex, hiPixelIndex);

  }

  let nullIndexLo = s.length * 8;

  let nullIndexHi = nullIndexLo + 8;

  if (nullIndexHi + 3 < pixelArray.length)

    EncodeCharacter(0, pixelArray, nullIndexLo, nullIndexHi);

}

​

​

function EncodeCharacter(code, pixelArray, loPixelIndex, hiPixelIndex)

{

  let bits01 = (code & 0b00000011) >> 0;

  let bits23 = (code & 0b00001100) >> 2;

  let bits45 = (code & 0b00110000) >> 4;

  let bits67 = (code & 0b11000000) >> 6;

  WritePixel(pixelArray, loPixelIndex, bits01, bits23);

  WritePixel(pixelArray, hiPixelIndex, bits45, bits67);

}

​

​

function WritePixel(pixelArray, pixelIndex, rBits, bBits)

{

  let r = pixelArray[pixelIndex + 0];

  let b = pixelArray[pixelIndex + 2];

  pixelArray[pixelIndex + 0] = (r & ~0b11) | rBits;

  pixelArray[pixelIndex + 2] = (b & ~0b11) | bBits;

}

​

​

function DecodeImage(pixelArray)

{

  let output = "";

  for (let i = 0; i < pixelArray.length; i += 8)

  {

    let loPixelIndex = i + 0;

    let hiPixelIndex = i + 4;

    let newChar = BuildChar(pixelArray, loPixelIndex, hiPixelIndex);

    if (newChar === null)

    {

      print(`Reached null after ${output.length} chars`);

      break;

    }

    output += newChar;

  }

  return output;

}

​

​

function BuildChar(pixelArray, loPixelIndex, hiPixelIndex)

{

  let loBits = DecodePixel(pixelArray, loPixelIndex) << 0;

  let hiBits = DecodePixel(pixelArray, hiPixelIndex) << 4;

  let code = loBits | hiBits;

  if (code === 0)

    return null;

  return String.fromCharCode(code);

}

​

​

function DecodePixel(pixelArray, pixelIndex)

{

  let r = pixelArray[pixelIndex + 0];

  let b = pixelArray[pixelIndex + 2];

  let rBits = (r & 0b11) << 0;

  let bBits = (b & 0b11) << 2;

  return rBits | bBits;

}

​