Projectors with same white output,
different colour light output
click for larger image

Colour Light Output:
New Projector Performance Metric

It’s no secret that when projection buyers are examining multiple projectors, image quality is a top consideration. But, take two projectors with similar specifications and pricing, and set them up side-by-side.  Will they show the same image quality?  Perhaps not.

On the right are images of actual output from two SVGA, 2200 lumen projectors.  The images were taken in a carefully controlled laboratory environment to best capture the colour performance of each projector.  As you can see, there is a dramatic difference in colour output between the two.

If they have similar specifications shouldn’t they provide similar colour quality? 

Unfortunately, current product specifications such as brightness (or white light output), contrast ratio and resolution give no information regarding a projector’s ability to reproduce colour.  The existing brightness metric only measures the total amount of White light projected.  It does not measure colour.

So…aside from a head-to-head demonstration, how can a projector buyer accurately assess colour performance before purchase?

Fortunately, leaders in the projection marketplace have come up with a new metric that provides the buyer better information about Colour Performance. This new metric is called Colour Light Output (CLO).

CLO measures the primary colours of light - red, green and blue, using the same approach used to measure White Light Output in lumens.

By measuring red, green and blue…not just white…CLO measures a projector’s ability to deliver colour. Developed by colour scientists, Colour Light Output provides a simple, accurate and easy to understand way to evaluate projector colour performance.

Today, all video, DVD, HD, digital camera and computer signals are encoded in an RGB Colour Space – in all of these devices and in the world around us, red, green and blue combined equal white.  If the combined colours do not equal white, a full and balanced range of colour cannot be reproduced, and accurate colour reproduction is impossible.  CLO measures the brightness of red, green and blue, just like the input signal.  If a projector produces bright red, green and blue that combined equal the brightness of white, then true, accurate and balanced colour is possible. 

CLO can be used in conjunction with White Light Output to provide insight into a projector’s overall picture quality. If White Light Output is equal to CLO buyers can be confident that the projector will do a good job reproducing the RGB input signal. 

The CLO metric has been adopted by a number of leading projector manufacturers. Today, more and more projector specification sheets are listing the Colour Light Output metric. 

When evaluating projectors, a buyer should always ask for the Colour Light Output measurement.

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