The Secret Sauces of THG's LCD Tests

Color Rendering Tests

The most important quality we're looking for in a monitor, whatever the technology employed, is color accuracy. To measure the chromatic accuracy of displayed shades, we use LaCie Blue-Eye.

We use it as a calibrator, allowing us to verify the accuracy of the different shades with respect to gamma and color temperature settings.

The calibration provides us with a DeltaE graph for each monitor. This figure corresponds to the difference between the color we want and that actually reproduced. A DeltaE less than or equal to 1 is tantamount to perfect: there is no perceivable difference between the color expected and that rendered. Above a DeltaE vale of 3, the human eye can spot the difference.

On the x-axis (abscissa): the values go from black (0) to white (100). On the y-axis (ordinate): the corresponding DeltaE reading. The graph for our Prophetview 920 Pro shows:

  • DeltaE < 2 = 94 % of the colors displayed, from dark grey to white, are correct.
  • DeltaE < 1 = 76 % of the colors are perfectly reproduced.
  • DeltaE > 3 = 4 % of the colors displayed are not correct. This is invariably the case with darker colors on TFT monitors.

This test allows us to tell:

  • The contrast level in the calibration conditions;
  • The depth of black displayed;
  • The real brightness of the screen.