Colour Perception

Colour Constancy

Colour constancy is an area of psychology that deals with the way we perceive colour under different contexts. In simple terms it has to do with the Blue/Black vs White/Gold dress phenomenon you might remember from twitter.

Very simply explained - the brain adapts to the whitest white in the scene (or what it thinks is the whitest white) and tries to white balance (like a camera) based on that white. So if that white is warmly lit it will automatically change the perception of the colours so that they are preserved. This sometimes creates some strange illusions that we just cannot avoid because we are hardwired.

In order to avoid such ambiguities in our images there are some simple rules we can follow when designing, composing and lighting sets.

This is NOT to be confused with actually making sure that our sets are white balanced in the virtual camera and in post. This stuff is covered in other guides. This is purely about perception and how the relative mix of colours in the set affect PERCEPTION.

Check these videos out and you will quickly understand the principle. 

Check these videos out and you will quickly understand the idea. 

Background info

A bit more in depth from WIRED. 

Example of where it could cause a problem:

Scenario 1: 

ok. so basically you have a room, the ceiling is white, the wall is blue. you take a picture with warm light, and you don't white balance - your brain 'assumes' the ceiling is white because there is nothing else there and changes the colours of everything in the picture to compensate for the ceiling looking a bit yellowish (thinking its meant to be white). This happens on the level of your brain hardware.

Scenario 2:

so scenario 2 you paint the ceiling beige (or something warm off white but not quite white, or light grey), you light the set with white light. you actually white balance for the light in camera.  your brain assumes the ceiling is white but warmly lit and changes the colours of everything even though they are all fine and correctly lit.

Scenario 3:

This is more to do with lighting and exposure (the black and white version of that illusion above). If you say have lots of light greys and no white, even if the scene is exposed correctly the brain will think this is an under-exposed white rather than a grey. It will think the lightest grey is actually white and this is a really dark set. 

Things to do to avoid this

Simply making sure that there is an object that the viewer will know is white, or percieve as white (doesn't have to be perfect white but should be close enough so that when the scene is white balanced is more or less white). Remember, white balance in camera is a separate thing. This is about the brain. 

Here are a few examples of good practice