deinterlace = function deinterlace(pixels, width) {
  var newPixels = new Array(pixels.length);
  var rows = pixels.length / width;

  var cpRow = function cpRow(toRow, fromRow) {
    var fromPixels = pixels.slice(fromRow * width, (fromRow + 1) * width);
    newPixels.splice.apply(newPixels, [toRow * width, width].concat(fromPixels));
  }; // See appendix E.


  var offsets = [0, 4, 2, 1];
  var steps = [8, 8, 4, 2];
  var fromRow = 0;

  for (var pass = 0; pass < 4; pass++) {
    for (var toRow = offsets[pass]; toRow < rows; toRow += steps[pass]) {
      cpRow(toRow, fromRow);
      fromRow++;
    }
  }

  return newPixels;
}
Deinterlace function from https://github.com/shachaf/jsgif