RGB - Full vs. Limited

When talking about RGB, you may have heard the terms “Full RGB” v “RGB Limited” thrown around and perhaps you’re wondering what it all means and how it even affects you.

Now while it may seem that a Full RGB would be the best option - after all the term full would indicate superiority - that isn’t necessarily the case. But to fully grasp why, first we need to understand how RGB works.

RGB was originally developed by engineers from Microsoft, HP, Intel, as well as some others. The scale has 255 levels; 0 represents absolute black on a display and 255 stands for absolute white.

Full RGB means that a machine has the ability to show absolute blackness and absolute white and all the other 253 shades in between. RGB Limited has a range of 16 – 235.Its absolute black is 16 levels brighter (or less dark) than Full RGB and its max white (or brightness) for RGB Limited is 15 levels lower (less bright) than for Full RGB.

Simple… but the question still remains, what’s the difference for consumers between the two colour technologies.

A good example here is Hollywood; big blockbuster movies now use so many effects and CGI processes, horror movies make use of dark and shadow in a purposefully underexposed way and action movies use a lot of stunt and wire work, which needs to be concealed in post-production. Because of this, cinematic and creative arts organizations have, on the whole, adopted RGB Limited as Full RGB range will, by its very nature, overexpose elements that were not intended to be seen. In turn making it look worse and affecting the end user quality and experience.

PC monitors by default run the Full RGB range. But if you leave it in Full RGB mode and use the monitor to view limited RGB sources, you’ll get crushed black levels. In essence, the dark areas of the image will appear too dark and completely lacking in detail. Fortunately a lot of internal apps and streaming services have become good at auto adjusting, however Blu-rays are hard coded to RGB Limited. So, if you were to consuming content via a monitor you should, for the best quality results, manually switch across to RGB Limited.

As always there are two sides to every story, and forcing a Full RGB monitor to work in RGB Limited mode, will result in a washed-out image. Blacks become dark grey and detail all but disappears. Similarly, if you use a TV as your monitor, chances are you should be on RGB Limited. Forcing the TV to work in Full RGB will cause crushed blacks, as mentioned above.

So, what’s the solution?

Unfortunately industry standardization has not yet reached a point whereby there is a single unified means of RGB identification, nor is there a fully unified system of displays and sources being able to automatically switch ranges for content.

Until that time the best thing to do is stick to a simple rule of thumb… for a PC on a monitor choose Full RGB whenever possible. For PCs on a TV or Blu-rays on a monitor, RGB Limited should be the better option.

Link: https://www.benq.eu/en-uk/monitor/entertainment.html