text: var psnr = require('../');
  var test = require('tap').test;
  
  var original_1x1 = [128];
  var noisy_1x1    = [136];
  var original_2x2 = [0, 128, 192, 255];
  var noisy_2x2    = [0, 128, 173, 255];
  
  test('1x1 identical', function (t) {
      t.plan(1);
  
      var result = psnr(original_1x1, original_1x1);
      t.equal(result, Infinity);
  });
  
  test('1x1 different', function (t) {
      t.plan(1);
  
      var result = psnr(original_1x1, noisy_1x1);
      t.equal(result.toFixed(5), '30.06900');
  });
  
  test('2x2 identical', function (t) {
      t.plan(1);
  
      var result = psnr(original_2x2, original_2x2);
      t.equal(result, Infinity);
  });
  
  test('2x2 different', function (t) {
      t.plan(1);
  
      var result = psnr(original_2x2, noisy_2x2);
      t.equal(result.toFixed(5), '28.57633');
  });