Science proves gaming is better on CRTs than LCDs

Why professional FPS players are right to lug around CRT behemoths

In this X-Ray we’re going to put to rest the age old argument of “30fps is all you can see”. Much like Gates’ “640k should be enough for everyone” statement (misappropriated as it is), the debate over just what frames per second you need on screen for a game to seem ‘smooth’ is full of mis-information. If you’re in the camp that believes 30fps is the limit of human vision, stop reading now as we don’t want to break your fragile world. And speaking of vision, the human eye is where we’ll start this journey.

Analogue
The human eye is, as they say, a rather spiffy device. It’s capable of discerning an incredible range of colours and intensities of light, can dynamically adjust the amount of light that enters, and can focus on objects near and far with ease. It’s also an analogue device – no frames here, just constant signalling. We really perceive the world as a constant stream, and the annotation of frames per second we aspire to in games is all about duplicating this experience by rendering images so fast that the human eye can’t discern where one frame ends and another starts.

And just where is that boundary?

Colour and light
First it helps to understand a little about the human eye.

As light is focused on the retina it bathes two unique types of cells – rods and cones. Rods react to light intensity, but don’t react as fast as cones. It’s the rods that allow you to see in the dark with minimal light. However, they can’t detect the wavelengths of colour, which is why objects lose their colour at night.

Cones don’t work particularly well in the dark, but do detect colour very well. There are three types of cones, each attuned to the red, green, and blue spectrums – aka RGB. Actually it’s not quite that simple – as analogue devices and working in tandem, the cones detect the properties of colour in terms of hue, saturation, and brightness but it’ll suffice for our purposes here.



There are many more rods in your retina than cones – some 100 million rods to six odd million cones – and the cones are concentrated in a small area called the macula. The distribution for the light spectrum isn’t even, either. Generally, we’re able to perceive the green range better than red, and red better than blue. Indeed, there are more cones tailored to registering these as a result. It’s hard to imagine, but if our eyes could receive all wavelengths equally, a candle flame would appear red and not yellow.

Brightness and contrast
So what’s this got to do with frames? Keeping in mind the purpose of cones and rods, there’s another factor to consider – how quickly they respond to changes in light. Attuned to light as we are, it’s been established that the human eye can distinguish a change in the presence and intensity of light far more than it can of the absence of light. Said another way, light can create an afterimage in the eye, much like you get if someone rudely shines a torch in your eyes (more on this later). It’s possible for you to still discern an intermittent black background over a white one at a rate of 1/50th of a second, or 50Hz. Approaching 100Hz, it becomes all but impossible. However, distinguishing a white background over a black one can be easily noticed at 100Hz, and even as high as 200Hz. A much vaunted test the US Army once conducted found that pilots could distinguish the image of a plane at up to 220Hz, or 1/220th of a second.

Because the human eye is capable of adjusting to lighting conditions via the iris and chemical changes in the retina, the full dynamic contrast ratio of our eyes is estimated to be about 1,000,000:1.

Keeping in mind the human visual system is analogue, this is only a guide to the limits of the chemical reactions and brain processing that goes on constantly. It does show, however, that between light and dark we can distinguish changes as quickly as up to 200Hz.