When buying a projector one of the most important considerations is brightness, so the lumens rating is often one of the first factors considered when comparing models.

Yet buyers might be surprised to learn that the way lumens levels are reported can be quite misleading, because many manufacturers report the white brightness levels only. If you don’t consider the colour lumens rating when evaluating projectors, you may end up with a model that displays murkier colours and significantly less brilliant images.

In fact, third party testing found that the white brightness could be as much as 458 per cent higher than the colour output. That is a significant gap if you purchase a projector expecting them to be the same.

To make a smart decision when you buy your next projector, you need to understand a few basics about an important “hidden” variable: colour brightness.

What are lumens?

Projector manufacturers use the measurement of ANSI lumens – or just lumens – to report the total amount of visible light a projector emits. Lumens indicate how bright the output of a particular projector will be.

Unfortunately for those buying projectors, there is no requirement for manufacturers to report both the colour and white light brightness levels. Many simply report the white light levels and have significantly lower colour levels.

Unequal white and colour light levels can cause duller, less vibrant images. Not what you want if you plan to use colourful images, charts and possibly even video to bring your presentations to life.

Just how big can this gap be? Significant.

A list of third party evaluations found white values as much as 462 per cent brighter than the projector’s corresponding colour values. What’s more, 77 per cent of the models listed had a white brightness values that were at least 300 per cent higher than the corresponding colour brightness.

Here is a side-by-side example of just how different the projected images can be. For both images the projectors were set to full brightness. The image on the left measured white brightness of 2700 lumens for white brightness and 700 lumens for the colour brightness. The image on the right measured 2800 lumens for both white and colour brightness.

A push for making colour brightness a new standard

It’s not surprising that manufacturers like Epson, who ensure that all of their projectors have equal colour and white light brightness ratings, publish both numbers and also advocate for having all manufacturers publish both values.

Unfortunately there are many manufacturers that do not report colour brightness levels, which in and of itself can be an indicator that you should proceed with caution.

There are three manufacturers that I am aware of who are known for having equal white and colour lumens ratings in their projectors: Epson, Hitachi and Sony.

Interestingly, higher colour brightness levels does not necessarily mean that you will pay more.

How can I find colour brightness ratings?

What should you do if you are evaluating projectors where colour lumens are not reported?

One of the best options, when colour brightness is not reported, is to check reviews sites that include formalized image testing. For example, PC Magazine uses DisplayMate suite to evaluate the image quality of projectors it reviews.

It is important that reviews rely on standards, rather than a subjective interpretation of what the reviewer sees, so that different models can be accurately compared.

A word about chip technology

There are essentially two main chips options when purchasing a projector: DLP and 3LCD. According to Wikipedia DLP projectors are used in roughly 85 per cent of digital cinema projection. The 3LCD chips, which were originally developed by Epson and are now marketed by an affiliated organization, have been adopted by 40 different projector brands worldwide.

Except for high-end applications like high-end home theatres, most projectors that use DLP technology will have a single chip. While DLP technology has evolved and some models have some interesting innovations, including a new brightness and lamp-free projectors, 3LCD projectors still outperform DLP technology when colour brightness is considered.

The brighter colours in 3LCD technology was confirmed by both Epson and in the marketing materials of Viewsonic, a manufacturer that makes projectors using both DLP and 3LCD technologies. When referring to its 3LCD projectors Viewsonic notes that it used "…3LCD technology to produce more vibrant colors."

Claudine Wolas Shiva, senior marketing and product manager at Epson America, confirmed that with colour and white brightness levels are always the same with 3LCD projectors. So if having equal colour and white brightness leels is important to you, one way to ensure you get equal brightness is to focus on 3LCD projector options.

Cutting through the marketing hype

It can be hard to cut through the marketing hype from different manufacturers, but as a consumer it's important to be educated about what the numbers really mean.You need to be on guard for misleading specifications that imply high quality colour brightness with unrelated data.

For example, I saw advertising recently for DLP projectors that talked about 50 per cent brighter colours due to the use of a six colour wheel, rather than the three red-green-blue (RGB) colours used in most projectors.

On the surface of things that sounds fantastic, until you realize that 50 per cent brighter for a projector with a colour brightness rating equivalent to 22-40 per cent of the white levels is still lower than 100 per cent.

Does colour vibrancy really matter?

Colour brightness is just one of many factors to consider when purchasing a projector. Depending on your use other factors like portability, lamp life and connection options may be your most important considerations.

Those things may guide your buying decision and fortunately, are easy to compare.

Colour brightness, as you have seen, is not easy to compare. Yet if all other components are equal, this hidden variable could be an important factor in selecting the best projector for your investment.