1. A method for rating display quality comprising: capturing an image of the display; computing a first parameter value from the captured image; computing a second parameter value from the captured image; comparing the first parameter value against a threshold; if the first parameter value exceeds the threshold, computing a grade wherein the second parameter is given a first weighting; if the first parameter value is below the threshold, computing a grade wherein the second parameter is given a second weighting which is greater than the first weighting.