How does a camera work? Best Engineering Part 1
If you were to guess how many smartphone pictures will be taken throughout 2021
Q: What would you guess perhaps?
- A billion
- A trillion
- 50 trillion
- 1 quadrillion +
Here’s some stuff to help you out there are seven point six billion humans on earth the percentage of people across the globe who in smartphones is about 43% and let’s say each person takes around one photo a day thus the answer is around 1.2 trillion photos so one trillion is a pretty good guess that’s an astounding number of pictures but how many different parts of your phone have to work together to take just one of those pictures and that’s the question we are going to explore how do smartphones take pictures.
So let’s dive into this complex system to start we are going to divide the system into its components or subsystems and lay them out into this systems diagram first of all we need an input to tell the smartphone to load the camera app and take a picture this input is read via a screen that measures changes in capacitance and outputs x and y-coordinates of one or multiple touches this input signal feeds into the central processing unit or CPU and random access memory or RAM here the CPU acts as the brain and thinking power of a smart phone while the RAM is the working memory it’s kind of like what you are thinking of at any moment, software and programs such as the camera app are moved from the smartphone storage location which in this case is a solid-state drive and into the random access memory it would be wasteful if your smart phone always had the camera app loaded into its active working memory or Ram it’s like if you always thought of what you were going to eat at your next meal it’s tasty but not efficient once the camera software is loaded the camera is activated a light sensor measures the brightness of the environment and a laser rangefinder measures the distance to the objects in front of the camera based on these readings the CPU and software sets the electronic shutter to limit the amount of incoming light while a miniature motor moves the camera’s lens forwards or backwards in order to get the object in focus the active image from the camera is sent back to the display and depending on the environment an LED light is used to illuminate the scene finally when the camera is triggered a picture is taken and sent to the display for review and to the solid-state drive for storage this is a lot of rather complex components however there are still two more critical pieces to the puzzle and that is the power supply and wires all of the components use electricity provided from the battery pack and power regulator wires carry this power to each component while separate wires carry electrical signals to allow the components to communicate and talk between one another.
This is a printed circuit board or PCB is where a lot of components such as the CPU RAM and solid-state drive are mounted it may look really high-tech but it is nothing more than a multi-layered labyrinth of wires used to connect each of the components mounted to it if you want you can add other components to the diagram of your system however we limited our selection to these.
So now that you have the layout of a system let’s make a comparison or analogy between this system and that of the human body can you think of parts of the human body that might provide a similar function as those we have described for the subsystems of a smartphone,
for example, the CPU is like the brains problem-solving area while the RAM is the short-term memory, these are some of the comparisons that we came up with it’s interesting to find so many commonalities between two things that are so very different like nerves and signal wires both transmit high-speed signals to different areas of the body and smartphone via electrical pulses yet one is made of copper while the other is made of cells also the human mind has similar levels of memory to that of the CPU RAM and solid-state drive
Q: What do you all think?
A: Overall it takes a complete system of complex interconnected components to take just a single picture each of these components has its own set of sub-components details along with history and many future improvements this layer is starting to resemble the branches of a tree each element will be explored and detailed in other episodes however for the rest of this episode we will focus our attention on the camera but before we give you an exploded diagram of the camera and get into all of its intricate details let’s first take a look at the human eye.
- With the human eye, the cornea is the outer lens that takes in a wide-angle of light and focuses it
- Next, the amount of light passing into the eye is limited by the iris
- A second lens whose shape can be changed by the muscles around it bends the light to create a focused image this focused image travels through the eye until it hits the retina
Here a massive grid of cone cells and rod cells absorb the photons of light and output electrical signals to a nerve fiber that goes to the brain for processing, rods can absorb all the colors of visible light and output a black and white image whereas three types of cone cells absorb red green and blue light and provide a colored image now this brings us to a key question.
Q: If your eye only has three different types of cone cells each of which can only absorb red green or blue?
Q: How do we see this entire spectrum of colors?
A: The answer is in two parts.
First, each Red, Green, and blue cone absorbs a range of light and not just a single color or wavelength of light this means that the blue cone picks up a little light in the purple range as well as a little in the Aqua range
Second, our eyes don’t detect just a single wavelength of light at a time but rather a mix of wavelengths and this mix is interpreted as a unique color it’s kind of like cooking a soup it takes many ingredients chopped up and mixed together to make a complex flavor if you look closely individual ingredients can be identified but these ingredients taste very different on their own compared to the whole soup together this is why colors like pink and brown which are combinations of colors can be found on the color wheel but not on the spectrum of visible light so if this episode is about how smartphones take pictures.
Q: why are we talking about the human eye?