Problems of subjective perception of colors

Subjective perception of colours. Once two people were arguing about colours. One of them argued that all people see the same things, while the other disagreed. “Is your red the same as my red?” “Maybe you see “my” blue instead of red?”… And the debate continued.

You may find these things funny, amusing, or even pointless. But we all see the same thing. Yeah… all together it’s a lot more complicated than we might think based on this fictional debate. But maybe we really see colors differently? But let’s leave aside the anomalies such as color blindness and similar conditions. We can say with great certainty that our eyes received the same light in a certain situation as our interlocutor’s, and therefore also the colors, because they are part of the light. That part that we can just see with our visible receptors. Somewhere between 380 and 750 nm wavelength. So if our eyes are healthy and similar to the others, then we really look pretty much the same. Is that true?

What is the truth?

The difference, of course, is how we perceive these colors. After all, we look with our eyes, but we see with our brains. Let’s start by following this light. As is well known, there are two types of photo sensor cells: rods and plugs. Cells shaped like rods detect shading and shapes, and we need them for peripheral and night vision. Plugs are important for detecting details in good light and perceiving the colors of objects, but they do their job worse in low light and in twilight. The rods and plugs are distributed throughout the retinal area except at the point where the optic nerve is connected to the brain. The optic nerve transmits information obtained from the retina to the brain, which in turn transforms it into the image we see. That’s where uniformity ends. Each individual has their own, subjective system that translates this light into a visible image and because our brains are a wonderful machine that responds well to different situations and psychophysical states – this is what evolution has brought us to survive – we also see differently in different situations. At the same time, there is an emotional component that is a result of our experience and also contributes to individual perception.

An additional limitation is the ability of our eyes. Sensors (plugs and sticks) can be saturated when watching certain colors and the brain receives the wrong information. For example, if we stare at a green sheet of paper for a while and then look at a white wall, we will see the shape of that sheet for a few more seconds, but in reddish color? Why not in the green if we were staring at the green leaf? This is partly the fault of our tired cones and sticks, and partly the fault of the brain, which tries to compensate for the oversaturation with the opposite color, which in the case of green – red. So the brain sees oversaturation and tries to correct / even it out. Therefore, it is also subjectively difficult to determine a neutral white color, because our “processor” tries to compensate for any deviation and does so constantly without our awareness. We can also illustrate this with an example: when we enter a space lit by “warm” light, we will realize this. Over time, however, this feeling will disappear and we will feel that the light is white. So the brain adjusted and found a new central reference for white.

Is our visual system similar to a camera?

Not at all, although it has very similar components that can be compared to each other:

Eyeball – lens
Eye muscles – auto focus
Ophthalmic lens – lens system in the lens
Retina – sensor / film
Brain – processor

As we can see, in modern times we have taken a step closer by using a digital camera and processor because algorithms and sensors help us process light into what we would like to see. Let’s say photography in artificial light. In the case of an analog camera, we had to use different filters to equalize the light, but now this is done by a processor that processes the input signal properly. Just like our brains.

Conclusion

So we see colors really differently. This is partly due to circumstances, and partly due to the psychophysical state at the time of viewing. Through evolution, the human (and of course the animal) visual system has adapted perfectly to the various situations that have helped the specimen survive. Some species see, for example, less detail and more color, even beyond our human perceptions. Others specialize in low light conditions and colors are not so important to them. If we stick to our – human perception of colors, we are somewhere in the middle of nowhere. The system works great in nature, but when we are faced with work where colors are important in different situations, such as photography, printing, the automotive industry,… there we give up. Because the eyes / brain can deceive us in this way, it is important to use instruments that are independent of our perception when working with colors – spectrometers, calibrated light, color maps ino only in this way we will get repeatable results that will not depend on subjective looks.