PDF.js displays blurry plots in PDF documents, e.g.

http://arxiv.org/pdf/1202.5344v1.pdf

When viewed in Chrome or Adobe Acrobat all the plots show sharp-edged squares. When viewed in Preview or PDF.js, all the squares show as blurry pixelated blobs.

let xa, car, cag, cab;
  let xb, cbr, cbg, cbb;
  for (let y = minY; y <= maxY; y++) {
    if (y < y2) {
      let k;
      if (y < y1) {
        k = 0;
      } else if (y1 === y2) {
        k = 1;
      } else {
        k = (y1 - y) / (y1 - y2);
      }
      xa = x1 - (x1 - x2) * k;
      car = c1r - (c1r - c2r) * k;
      cag = c1g - (c1g - c2g) * k;
      cab = c1b - (c1b - c2b) * k;
    } else {
      let k;
      if (y > y3) {
        k = 1;
      } else if (y2 === y3) {
        k = 0;
      } else {
        k = (y2 - y) / (y2 - y3);
      }
      xa = x2 - (x2 - x3) * k;
      car = c2r - (c2r - c3r) * k;
      cag = c2g - (c2g - c3g) * k;
      cab = c2b - (c2b - c3b) * k;
    }