isProbablyAMeme.js

isProbablyAMeme.js

function isProbablyAMeme(ctx2, w, h) {
  // given a ctx, get it's pixel data
  var pixels = ctx2.getImageData(0, 0, w, h)
  
  // threshhold filter the pixels. looking for bright white a la bold impact meme text
  for (var i = 0; i < pixels.data.length; i += 4) {
    var avg = (pixels.data[i] + pixels.data[i + 1] + pixels.data[i + 2]) / 3
    var ne = avg > 240 ? 0 : 255
    pixels.data[i] = ne
    pixels.data[i + 1] = ne
    pixels.data[i + 2] = ne
  }

  var canvas = new Canvas(w, h)
  var ctx = canvas.getContext('2d')
  ctx.putImageData(pixels, 0, 0)
  
  // run OCR over the threshholded canvas, remove garbage from the detected text
  var ocr = Ocrad(canvas).replace(/\W|\_/g, '')
  // a handful of misidentified letters/numbers is ok, but not a dozen.
  return ocr.length > 12
}