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Physics/Science of Light (PART 14)

(How you could implement it + create dramatic compelling art scenes)

The Human Experience

When light either bounces off of surfaces, or is directly coming from a light source,it's going to enter through the pupil , hit a sensitive membrane in the back of the eye (the retina), and it gets decoded into a signal which is sent to

the image processing center of the brain where

the visual cortex is located. The visual cortex is extremely complex, people often say that no computer is as complex as the human brain because realistically no computer can do what this section of the brain can do. The way that it handles the imagery it is presented with and translates it into something meaningful is fascinating. What it can do is approximate visually what the dimensions of an object are, the distance of an object, what the relative colours of any given objects are to other objects, and relative values.

When our brains are trying to comprehend what it's viewing through our eyes it accesses the memory center of the brain and relates it to what we're hearing

It will access the language centers-a myriad of activities are occurring in the brain while it tries to interpret a visual signal.

Due to the complex processing that these visual images undergo, we're able to determine the different types of colours apart. And our brains are adjusting constantly according to the variety of colours it interacts with.

With this capability, you're able to tell that the right square (right) is cooler and the brown square (left) is warmer.

Yet when you look at the (left) small grey square here, that grey appears more cool against the brown surrounding it but when you look at the (right) small grey square looks a bit warmer than purple surrounding it.

There exists an entire branch of psychology dedicated to studying how our brains interprets situations like this.

Let's talk more about the physiology of it. Here's the pupil, the light comes in, it goes through the lens,

and gets spread out across the retina as light comes in. The iris will expand/contract in order to let more light in, or less light in depending on the situation. The adjustments that are happening in the iris constantly occur-every time you look at something different and every time your eyes change direction. The iris slightly shifts in size so tailor to accommodate the amount of light travelling in it.

The back of the eye (show) is also adjusting according to the amount of visual signals that are being received.

Our eyes see value and colour separately from one another. Value is seen with something called the rod cell, there are lots of rod cells. These parts are very sensitive to light which allows them to process different lighting situations. However they only see in black and white.The rod cells live along the bottom edges of the eye. (back of eye, along the edge where the stem is poking through)

Then there's the cone cells, which tend to see only in colour.

They have some pigment to them. (up where the cone is located, that top pyramid, circle it to demonstrate) Their job is to filter out the colours of the light, therefore any light able to pass through are picked up by the nerves down there and sent back down to the optic nerve.

There's 3 different kinds of cone cells.

Because a cone cell is less sensitive to light it tends to only see objects that are bright or any bright lights.

Generally speaking, value is more important than colour. That's not to say that colour isn't important, there are going to be times when colour will overpower the value cues in drawing your attention to something. But as far as visual accuracy goes, such as the ability to interpret what is happening in the scene , value is crucial.

Sometimes you can create a resonance between the values and the colours in your scene because your eyes view those two separately from each other; which enables you to experiment with different combinations of coalescence. For example, having the same colour in different values or having different colours in the same values; in juxtaposition with each other to create interesting effects.

Defraction and Glare

Something else happens, and this is because of the physiology of the eye, the eye, the eyelid ,eyelashes and the structure of our eyes affect the amount to light that enters in it.

There are other attributes that affect how we view light. A bring light being viewed can be perceived as much more brighter/stronger than it actually is. When we look at a bright light several activities are taking place in our eyes.

What's happening in our eyes?

If it's a very bright light, it enters in and spreads across the eye, then bounces around the liquid material inside which fills your entire vision with light that's much larger than what you're seeing. This is called glare.

Another occurrence that affects how we view light is when bright light strikes our eyes which may cause our eyelids to slightly close, thereafter the eyelash will starts to distort how light is viewed.

There's a principle called de-fraction, and that is when a wave interacts with an obstacle such as a small slit or the edges of obstacles which essentially cause an interruption in the course of path the waves are travelling on.

The obstacle the wave eventually interacts with causes a deviation in the direction the wave then travels. This interaction(defraction) causes the wave to curve and bend at a different angles depending on the properties of the surface it comes in contact with.

This is the case with your eyelashes, they kind of create a whole bunch of defraction slits for the light to travel through.

Which causes the light to spread out as it passes through the eye.

It enters through the eyes, spreads across our eyes, and you end up seeing rays.

When this similar interaction occurs in a camera, it's also caused by defraction but primarily it's caused by the imperfections in the lens. The effect it creates is very similar to the effect you see with your eyes. Another thing that you'll get with camera lenses is lens flare.

Gestalt Psychology

Gestalt psychology is a branch of psychology which focuses on the central principle of understanding our natural stimulus to differentiate between relative visuals and contrasting visuals. The natural ability to discern the apparent contrasting values from one object to another and the relative values of one object to another. There are different ways our brains process the (visuals) information passing through our eyes.



So one type is value, essentially all of these rectangles are the same grey except for the black. And because of that value change that one becomes the object of interest.


Next one is hue, even if everything is the same value, if you change the hue of one object, it stands out amongst the rest.

Saturation Saturation has the same effect on our brains, our eyes will view a highly saturated area and our brains will interpret it as an area of interest or the focal point of the scene. Highly saturated areas will draw our eyes to it.


Another one is shape.


Sharper edges have higher contrast in the value range, thus anything that is blurred will have a less value contrast. The harder edges immediately draw our attention to them before the softer edges.


Uniform texture will generally attract our attention less than texture that is varied and chaotic. Interesting diverse texture will always override any other textures that are dull and uniform in the scene.


Another one is proportion.


The proximity and distance of the single object from the rest of the objects make it the center of attention.

This may seem basic, however it's not something most people are consciously think about when setting up a composition unless you've been trained and studied these principles. Amateur artists will usually follow their own whims and arbitrary decisions when coming up with a piece of art. However setting up a composition based on these few principles will balance your scene appropriately with structure and definite intention.

High contrast Areas

The first thing you need to think about when you're setting up a light scheme:

-the intended main subject of the scene

-how the light is going to affect the highlights and shadows of the subject

-Areas of high contrast draw the eye

There has been studies that artists see the world differently than other people. However if someone wants to see the world the way an artist would, it is possible through training. Our brains are very flexible and capable of expanding in response to the amount of stimulation it has undergone; therefore training it consistently will have you pay attention to details most often overlooked.

Once you understand Gestalt psychology, you'll comprehend why our eyes are more attracted to areas of high contrast and how they serve as areas of interest as our eyes move across the compositional points of an image. Gestalt psychology is particularly critical for artists to understand if they want to effectively implement it into their scenes.

If your stare at something in lower light, you're going to see some fluctuations in the values arise. This is also true with cameras in lower lit settings. These fluctuations that take place even in cameras with high quality sensors.

Why do slight fluctuations in colour occur within cameras in low lit settings?

As individual photons strike the sensor in a camera, each one sends a burst of energy and a slight amount of colour. This is why we see noise in photographs taken in low light situations. The darker the setting the more noise you will get. In that noise there's slight fluctuations of value, colour and saturation caused by the sensor's interaction with the photons. There's "good noise" and "bad noise" in response to these interactions. "Bad noise" is caused by poor electronic mechanisms and "good noise" is caused by a natural response to light. If you take photos with a very high quality camera you'll get "good noise" while low quality cameras create "bad noise".

Great painters will never paint a flat surface; they'll always paint in speckles of different colours mingling with the predominant colour of a section. These tiny hints of speckles of colour have subtle shifts of colour variations which add richness to the over appearance.

When your eyes move around they're constantly adjusting and bringing specific areas in focus or out of focus and so forth. When you're intention is to direct a person's eye to a specific area of an image you must be careful how you distribute the sharp/hard edges against the soft edges. The focal point of the composition is usually sharp while the background/insignificant areas have soft/blurred edges; this will create balance and direct your viewer's eye to the most important part of the scene. It can also add visual energy.


Another type of edge effect that you'll most likely come across in photography is called chromatic aberrations. When light travels through a lens, the light gets refracted and causes minor colour shifts along the edges of objects-this is called chromatic aberration.

This effect can be seen in this photo.

Expensive high quality lens try to correct these extremely subtle colour shifts so that very little chromatic aberration is visible however those are exceptionally expensive. Because we are often used to seeing this subtle effect it often doesn't strike as distracting or unnatural. You're able to see the red edges and blue edge colour shifts along here.

Depth Effects

When a camera is set to wide aperture, the opening of the camera is larger which allows more light to enter. The lens will focus down on a specific focal point compensating its distance from the object.

(1st pic) The object in focus is going to be sharp in comparison to anything outside the focal point such as the background (which will be softer/blurry) or vise versa (the foreground will be softer/blurry).

This makes the object in focus sharper in comparison to anything outside the focal point.

However if you move the lens away, there is no longer a specific point for the lens to focus on and the increased distance will cause the light travelling in the lens to spread. The light diffusion that occurs in the lens makes it harder for the camera to focus on a specific point. (refer to 2nd pic)

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