17" LCD Part IV: Six Panels With 16 And 20 ms

Two Important Factors

Take a one-year-old monitor. A year ago, excessive afterglow (blurring at every movement on screen) meant it was no good for fast action games. And its colors were not true enough for touching up photos. We realized that two important factors had a major influence on these issues: response time and contrast levels.

The response time is the average time required for a liquid crystal cell to go from active to inactive and back to active again. Roughly speaking, it refers to the time needed for a pixel to change from black to white and black again. The time is expressed in milliseconds, and the longer it takes, the slower the monitor's reaction. There is a direct link with image output, as well. For example, a 20-ms monitor will display 1/0.020: 50 dark then light images per second, or a total of 100 images per second.

The contrast level is the ratio between an image's brightest and dark points. The higher it is, the better the monitor will reproduce in-between shades. In practice, this level gives the number of grays the monitor can display.

The Progress Made

A lot of manufacturers now make 16-ms and 20-ms monitors. The first two were the Iiyama AS4314UTG and the Hitachi CML174SXW . NEC, ViewSonic, Hyundai and many others have since joined the fray.

Contrast-wise, monitors have evolved at the same rate. The ones we tested last year were of the 300:1 ratio. This year, it is not unusual to find ratios of 500:1.

This being the case, we felt this test should involve monitors with response times of less than 20 ms and decided to make it the occasion to review our test methods. Monitors will henceforth be calibrated according to the rulebook with a detailed assessment of color display precision. For this we used the LaCie calibration probe. For the rest - games, test charts, DVDs, etc. - the system is still the same.