Video Projectors and Color Brightness

Video Projector Color Brightness Comparison - DLP vs LCD
Video Projector Color Brightness Comparison - DLP vs LCD. Photo © Robert Silva - Licensed to About.com

The Lumens Game

When considering the purchase of a video projector, probably the most obvious specification that you become aware of is the lumens number. Lumens is a measure of the how much light a video projector can output. Of course, just as with other specifications, when a manufacturer provides a lumens specification number, you have to cautious as there is no standard that is specifically required to used - so a stated Lumens rating used by one brand of projectors may not be the same as another brand.

However, if the lumens rating is stated in terms of ANSI lumens, that is an industry standard that is consistent if comparing two brands and both are using ANSI as their reference.

White Light Output vs Color Brightness

However, there is more to consider in terms how much light a video projector can output. When a single lumens rating is stated, what it is referencing is how much White Light Output (WLO) or White Brightness, the projector is capable of producing, not the total light output when color is taken into consideration. For example, two projectors can have the same WLO rating, but the color light output (CLO), or Color Brightness, may be different.

Side-by-Side Comparison

To illustrate the difference between White and Color Brightness, the above photo shows a side-by-side demonstration of the effect of color on video projector lumens, or light, output. Both projectors in the photo have the same White Brightness output but differ in the amount of Color Brightness they can project.

The reason that there is a difference in the Color Brightness of the two projectors is that the projector on the left side uses a 1-chip DLP design (Optoma GT750E), while the projector on the right used a 3LCD design (Epson PowerLight Home Cinema 750HD). Both projectors have the same native display resolution (720p) and the same ANSI lumens WLO specification: 3,000.

The stated contrast ratio for the Optoma is 3,000:1 and for the Epson is stated as "up to" 5,000:1.

However, as you can see, the projector on the right appears to have brighter, more vibrant colors, as well as overall brightness, than the projector on the left.

How Projector Technology Design Affects Color Brightness

The reason for the difference in actual displayed images, that you see in the photo, is specifically related to the design of the two projectors. The 3LCD design allows all of the white and color light to pass through the lens continuously, projecting and equal amount of both White and Color Brightness. However, in a 1-Chip DLP designlight has to travel through a spinning color wheel that is divided into red, green, and blue segments.

In the 1-chip DLP system, colors are projected sequentially (in other words, your eye is not receiving color information continuously), which can result in much lower color light output, in relation to the white light output. To compensate for this, 1-chip DLP projectors many times add a white segment to the color wheel in order to boost While Brightness, but the fact remains that the degree of Color Brightness is less than the White Brightness.

This difference is usually not stated by the manufacturer in their projector specifications. What you most often see is a single Lumens output specification, rather can one that lists two lumens specifications, one for WLO (White Light Output) and one for CLO (Color Light Output), which provides a more accurate profile of how much Color Brightness the projector can produce.

On the other hand, 3LCD Projectors employ a mirror/prism assembly (no moving color wheel) in combination with a separate chip for each primary color (red, greed, blue), so both white and color continuously reach your eye. This results in consistent White and Color Brightness.

As a direct result of the technology used to project images from each projector used in the above photo, for the 1-chip DLP projector on the left to produce as much Color Brightness as the 3LCD projector on the right, it needs to have a much higher White Light Output capability than the projector on the right - this means 1-chip DLP projector would have to use a higher-wattage lamp, and the resultant increase of power consumption.

Final Take - Why Color Brightness is Important

As you can see by the photo example at the top of the page, Color Brightness has a direct effect on what you see on the screen. This can be especially important not just for typical home theater viewing, but for viewing in rooms where the presence of ambient light may be able to be easily controlled, 3D viewing, where brightness loss when viewing through 3D glasses is a factor, and for those that use video projectors in educational, business, including traveling, where the projector may be used in a variety of rooms where light control is not known before hand.

Also, increased color brightness also increases the perception of details within the image, regardless of the display resolution. The only factor that can suffer when color brightness is increased is overall contrast level. However, there are other video processing factors that can affect this result.

For more details on the Color Brightness Standard, refer to the Official Announcement and the Color Brightness Standard White Paper.

Also, to compare Color Brightness specifications for select video projectors, check out the Color Light Output Projector Comparison Page.

For more about Lumens and Brightness, as well as how video projector light output relates to TV light output, refer to our companion article: Nits, Lumens, and Brightness - TVs vs Video Projectors.