Thursday, June 5, 2008

You Should Ignore Projector Contrast Specs

Now you may be asking yourself just why you should ignore the contrast specifications when looking at projectors. Well the answer is quite simple. They don't tell very much if anything at all about what kind of picture you should expect to see on the screen, and they say even less about how one model will compare to another. While vendors aren't posting distorted or false specs to try to make the projector seem better, its just that the contrast ratio is the least informative spec on the sheet.

Why Are Projector Contrast Ratios Worthless?
  • First and foremost, contrast ratios for projectors are not measured on the same basis and are influenced largely by many unstated variables. One of the most significant factors to consider are the projectors operational differences. Some projectors have dynamic irises that open and close to adapt to the amount of light that needs to be projected depending on a given scene. Others have color wheels with white segments that are turned off when dark colors are displayed and other projectors don't have any of these features. Because of this there is little to no basis of comparison between projectors.

  • There is another equally if not more important factor to consider that is often ignored on the projector spec sheet, and its known as gray scale. Imagine if you will you had a project that produces the highest contrast ratio on the market. Imagine it produced the darkest and deepest black you've ever seen and some of the most brilliant whites. Sounds nice doesn't it? Now imagine that this projector couldn't distinguish between subtle shades of gray. It would surely produce a horrible picture that you would have never expected by just looking at the contrast ratio.

  • When manufacturers measure contrast ratios for their machines they use special dark rooms with no ambient light to measure the contrast ratio. Unless you have a totally black room your own perception of contrast will not be nearly the same. Any amount of light that reflects in your room will cause the contrast ratio to drop in your projector. This light may come from light reflected from the projector screen, ambient light in the room such as windows that let in light, or light leaks from the projectors vents.

  • Another important factor to consider is the lumen output of the projector itself which will have an impact on how you perceive the contrast ratios. If you've got ambient light in your room one of the easiest ways to help solve this problem is to use a projector with higher lumen output. This is because light in the room defines the minimum black level, while lumen output from the projector determines the brightness of the highlights. In many situations it is often the projectors lumen output responsible for the range between the black and white on the screen and not the contrast ratio. However, there is a limit to how many lumens you should use. Using an extremely bright projector in a dark room will undoubtedly strain your eyes and give you a headache. Rapid transition from dark scenes to bright scenes that can often be distracting and painful.
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