ANSI Lumens vs Color Light Output: The Debate between LCD and DLP
This comparison of two particular DLP and 3LCD projectors shows that the traditional ANSI lumen spec and the new Color Light Output spec can both be highly misleading, but for different reasons.
The ANSI lumen spec is a problem because it does not take either color brightness or color accuracy into account. Knowing that a projector is rated at 3000 ANSI lumens does not tell us anything about color saturation, color accuracy, image tint, or how dim colors might be. Projectors can and often do deliver bright but unattractive pictures at their rated ANSI lumen output. How much light must you sacrifice in order to get a balanced picture? The ANSI lumen spec gives you no idea. So it is really no standard at all.
Into this ANSI lumen mess comes the new CLO spec which suffers from similar limitations that plague the ANSI lumen concept: It does not take color accuracy into account, and it reveals nothing about whether the projector is calibrated to retain highlight detail. So you can have two specs on a product sheet that says "ANSI Lumens: 3000 and Color Light Output: 3000" and still end up with a picture you would not want to watch.
Despite the flaws it has in common with ANSI lumens, the CLO spec does point to a real difference in how color and white light are created on three-chip projectors vs. single-chip DLP projectors. Practically speaking, the CLO spec is used as a marketing tool to highlight what several 3LCD vendors see as a weakness in the design of single-chip DLP projectors. The DLP vendors counter with the claim that the white filter is no weakness at all, but rather the extra white light increases the brilliance and apparent contrast of the picture and thus should be viewed as a benefit.
Setting aside the marketing rhetoric, this study shows that the color limitations in single-chip DLP projectors can be real. To that degree the proponents of CLO make a valid point. Buyers should be aware that an LCD and a DLP projector with the same ANSI lumen rating may not deliver the same brightness of color images. However, the fact that CLO is not based on any color balanced standard leaves it open to much of the same criticism that ANSI lumens suffers. In this test, our LCD projector lost 24% of its brightness after adjustments to remove the blue/green tint and to regain highlight detail. So if a projector is rated at 4000 Color Light Output lumens, but only produces 3040 lumens once the picture actually looks good, that is something buyers should know as well. But the CLO spec remains silent on this issue.
Specsmanship is and always has been a marketing game, at least where brightness and contrast specs are concerned, so the controversy will continue. One thing is certain--the debate will raise awareness of not only the inadequacy of the ANSI lumen spec, but the inadequacy of all attempts to quantify a projector's brightness without a more comprehensive and commonly agreed upon set of standards.
|Contents:||Introduction||Executive Summary||Test Set Up||TEST 1: Uncalibrated|
|TEST 2: Calibrated||Concluding Thoughts|