What is projected color brightness?

Many projector manufacturers tout a relatively new specification, color brightness, as one of the prime selling features of their projectors. Why might this metric be important when look to purchase a projector?

The viewer’s awareness of color has been raised significantly by improvements in digital technology. The images seen today on computer monitors, tablets, smart phones and HD televisions provide full range, saturated, vibrant color. This viewing experience leads to the expectation that, when projected on a large screen, these images will retain the same depth and richness of color.

That expectation has not always been met.

Digital projectors use either sequential color systems with a white segment (often a spinning color wheel) or a tristimulus color system. It turns out that when the same image is projected side-by-side, sequential color system projectors do not match the color brightness of tristimulus color system projectors. In fact, the viewer’s perception of color is much better when the projector use the tristimulus system.

Over the years, the mantra of “high brightness” drove projector manufacturers to favor single-light modulators and sequential color wheels that often won the high light output competition. This approach led to an emphasis on “white lumens”, ultimately at the cost of rich color.

In the last few years, with the help of a new standardized method for measuring “color lumens” as a distinct metric, some projector manufacturers have adopted the theory that good projector design should produce a similar level of illumination for a color image as it does for a white image.

In 2012, the Society for Information Display (SID) released its Information Display Measurements Standard (ICDM). For the first time, included in the ICDM is a section on how to quantify color brightness or color light output.

Now, for many projector models, color light output and standard (or white) light output each have lumen values in the specifications.

Two projectors may have the same (white) light output (say 5000 lumens). One projector also has a similar color light output (5000 lumens). Both projectors can achieve the same overall brightness at full power, but only one will render intense, rich color.

In projection applications where color intensity and saturation is critical, look for a color light output specification in the projector literature. Then compare that specification across different projectors. Theoretically, the highest color light output will provide the most color saturated projected images.