What is the colour of the building in the above image? Do you think it’s blue? Then read on.

If you are a real estate developer or an architect working with a 3D visualiser for architectural visualisation, you might have experienced a frustrating incident where your white building has started looking yellowish in the day view of the rendering. During the whole process, you must have emphasised on white being the colour of the building and yet the end result has left you with irritation. Adding to your frustration, the artist/firm assure you again and again that the colour of the building is in fact, white; even when you know that your eyes aren’t lying to you. So what is exactly wrong here? Whose fault is it?

Truth be told, it is nobody is wrong in this scenario (assuming the artist didn’t actually goof-up while selecting the colour). The whole predicament is due to the gap between our perception (the one that our brain creates for us) and the reality. To explain it further, we need to delve into a bit of science first.

Colour, light and how we see it

We have all learned the basic theory in the school. White light is made up of a spectrum of various colours (remember VIBGYOR). As the light fall on any coloured surface, say green grass, the surface reflects the spectrum of colour that is similar to its colour and absorbs the remaining light spectrums. Upon receiving this light in our eyes, the green spectrum lets us know the colour of grass.

We also know that the white coloured surface will reflect all the light and that will tell us the that the surface is white.

Here’s a catch though, we always assume that the light is white in all these scenarios. What happens when the light itself is missing a few of spectrums and is of a different colour? This where things get interesting and we aren’t really much aware of it.

In case of a light with strong hue, like red, the white surface will reflect the light as is so the surface itself will appear red to us.

Take this fact and combine it with another fact that sunlight has a yellowish tinge and voila! You can understand why the white building looks yellow. The White House itself looking yellowish in the sunlight should put your doubts to rest.

It’s not us! It’s the brain

Yet the story doesn’t end here. The talk of light bouncing off of surfaces is just physics but us seeing the colours also involves biology, and quite a bit complex one at that. The reflected light enters our eyes and is sensed by two types of cells (photoreceptors), Rods and Cones, in our eyes. The Rods sense the intensity/brightness of the light and the Cones sense the hue of the light. It is the combination of the sensory data of these 2 that helps the brain make up its mind about which colour we are looking at.

But as it turns out, the brain doesn’t just interpret the data, it also thinks and makes a judgement based on past experiences. That is exactly what forms our perception. That’s what creates the difference between what we are actually seeing and what our brain thinks what we are seeing. That sounds more philosophical but is true nonetheless. There are quite a few illusions that can reveal this fact.

Are you thinking that the square A and square B are of different shades of grey? Look Again.

The above one should be enough to question about are we seeing exactly what is in front of us. But the key point to learn from it is that brain tries to make sense of what we are seeing and even if the above example makes it look like a nuisance, it helps us more than we can fathom. This is the same ability that helps us determine the colour of a white building as ‘white’ even when we are seeing it in yellow sunlight.

The problem arises due to the fact that the brain’s ability to make a judgement call regarding colours only applies to reality and, to some extent, to photography. What it doesn’t apply to is architectural visualisation. It is the artistic outlook embedded in the archviz images makes them distinguishable from the photographs thus stopping the brain from running his usual interpretation method towards them. That is why you do not perceive a white building in yellow light as white; you tend to see it as yellow.

Additional Complication: Reflected light

Another aspect that messes up the colours of wall surfaces, exteriors as well as interior, is reflected light. To understand this aspect, it is essential to understand a few things. As mentioned earlier, coloured surfaces reflect colour that resembles their own colour. The rays usually to bounce off of multiple surfaces before reaching to our eyes. During their journey, each of these surfaces affects the spectrum differently. Also, since the light source isn’t focussed in a single direction, the scattered rays create infinite combinations of where the rays hit and bounce off. That is why there is always an occurrence where the faint-coloured or white coloured surfaces near the surfaces with a strong hue will have show a tinge of the nearest coloured surface.

Photography and today’s sophisticated architectural visualisation softwares use the same physics principles. So their results are very much realistic, except our brain doesn’t perceive it as reality and doesn’t add its ‘autocorrect’ mechanism. That is why the images look unnatural or wrong to us despite them being the closest thing to reality.

So what to do?

The knowledge to partake here is that light acts in a more complex manner than we usually assume and we need to think a bit more about the surroundings to ensure that surfaces are showing their true colours. Granted, the modern softwares let us take care of these factors, may it be 3D or photography; but even they have a few limitations, especially in case of photography. No matter how hard you try, a white building at night is going to end up looking bluish. You can photoshop it from head to toe but then you are sure to make it look surreal rather than real.

Bottom line, when you are thinking about asking for a colour correction, just remember, it’s good for a few minor oddities but if you are going to pursue showing the exact same colour of the shade card, nobody is going to like the result when you reach there.