The Illusion
When you watch a movie, a television show, or a video online, does the image move?
Despite what your brain is telling you, the answer is “no.” All you are seeing is light.
So why do you perceive this as movement?
Consider how a flipbook works: A series of images is presented to you in rapid succession. Your brain connects the individual stills to create an illusion of movement.
Once again, your brain is making order out of chaos, in this case using a mechanism referred to as persistence of vision.
Each image is presented for a brief moment, disappears, and is replaced by a subsequent image. The brain retains the memory of each image slightly longer than the eyes see it. As a result, the brain connects all the images into a seemingly moving whole.
The motion picture camera utilizes this mechanism by recording many frames per second. When these images are projected on a movie screen, television screen, or computer monitor, we perceive movement much like with a flipbook.
The number the individual frames and the speed at which they are recorded and played back is known as the frame rate. This is measured in frames per second, or FPS. Many different frame rates exist, and their functions and uses have evolved over time. In general, the higher the frame rate (and playback), the smoother the image.
Note: The eye must see a minimum of 12 frames per second (fps) for persistence of vision to work effectively. The higher the frame rate, the more fluid the illusion of movement.
What is a frame?
It is the box that serves as your canvas and within which you create windows into other worlds. All film and video images exist inside a frame.
See the frame below? Look at it a little closer. Move the slider below the image to magnify it.
The closer you get to the image, the more it starts to break up, until all you are looking at is a series of various colored dots. Move further away, and the dots resolve themselves back into an image.
These dots are referred to as pixels.
That we can perceive a collection of pixels as an image is thanks to a mechanism in our brains called brain reassembly. This is the brain’s way of making order out of chaos—a way of turning seemingly random pixels into patterns.
At which point can you tell what the following image is? Move the slider below the image to resolve the pixels.
The shape of the frame is always a box, but it can have different dimensions. Sometimes it is more of a square, and sometimes it is more of an elongated rectangle. This is the frame’s aspect ratio, and it affects how the image within is presented and influences how it is perceived. Aspect ratio is calculated as a ratio of width to height, ie. Width:Height
How does a different aspect ratio affect the audience’s perception of the image? Move the slider below the following image to explore different aspect ratios.
Not all images are created equal. Depending on the number of pixels that form the image, that image will have more or less detail in it.
In video, pixels cluster together in lines of resolution. The more lines of pixels, the higher the quality of the image. Resolution is the number of horizontal lines that make up each frame.
Video formats vary greatly in quality depending on the number of lines of resolution that they can store.
Note: Film is a photographic medium that requires chemical processing to produce a frame. Instead of pixels, film is comprised of silver halide crystals that react to exposure to light. Film formats vary depending on how large the film gauge is. The larger the gauge, the more silver halide crystals can fit on each frame, resulting in more image detail.
What you put in the frame and how you put it there are questions that you will be answering in perpetuity. Every time you embark on a new project, you will ask yourself what to show and how to show it. And it all sits neatly (or sometimes not so neatly) inside the frame.
