Last month my phone fell from my pocket & got wrecked screen (trust me on this don’t keep your phone in that neat shirt’s pocket) turns out i need copy of bill to claim warranty so i went through all old stuff bills & boxes, i finally found the box with bill still in it but a particular word caught my attention “CMOS sensor” out of curiosity i googled & ended up knowing a lot about digital cameras ? (FYI CMOS is Image Sensor).
How Digital cameras work?
Digital cameras look very much like ordinary film cameras but they work in a completely different way. When you press the button to take a photograph with a digital camera, an aperture opens at the front of the camera and light streams in through the lens. So far, it’s just the same as a film camera. From this point on, however, everything is different. There is no film in a digital camera. Instead, there is a piece of electronic equipment that captures the incoming light rays and turns them into electrical signals. This light detector is one of two types, either a charge-coupled device (CCD) or a CMOS image sensor.
Light from the thing you are photographing zooms into the camera lens. This incoming “picture” hits the image sensor chip, which breaks it up into millions of pixels. The sensor measures the color and brightness of each pixel and stores it as a number. Your digital photograph is effectively an enormously long string of numbers describing the exact details of each pixel it contains.
Images you take are compressed
Image for a moment that you’re a CCD or CMOS image sensing chip. Look out of a window and try to figure out how you would store details of the view you can see. First, you’d have to divide the image into a grid of squares. So you’d need to draw an imaginary grid on top of the window. Next, you’d have to measure the color and brightness of each pixel in the grid. Finally, you’d have to write all these measurements down as numbers. If you measured the color and brightness for six million pixels and wrote both down both things as numbers, you’d end up with a string of millions of numbers—just to store one photograph! This is why high-quality digital images often make enormous files on your computer. Each one can be several megabytes (millions of characters) in size.
To get around this, digital cameras, computers, and other digital gadgets use a technique called compression. Compression is a mathematical trick that involves squeezing digital photos so they can be stored with fewer numbers and less memory. One popular form of compression is called JPG (pronounced J-PEG, which stands for Joint Photographic Experts Group, after the scientists and mathematicians who thought up the idea). JPG is known as a “lossy” compression because, when photographs are squeezed this way, some information is lost and can never be restored. High-resolution JPGs use lots of memory space and look very clear; low resolution JPGs use much less space and look more blurred.
Important parts of Digital Camera
- Batteries: This camera takes two 1.5-volt batteries, so it runs on a total voltage of 3 volts (3 V).
- Capacitor: The capacitor charges up for several seconds to store enough energy to fire the flash.
- Flash lamp: Operated by the capacitor. It takes a fair bit of energy to fire a xenon flash like this, which is why a lot of flash photography quickly uses up your batteries.
- Lens: The lens catches light from the object you’re photographing and focuses it on the CCD
- Focusing mechanism: This camera has a simple switch-operated focus that toggles the lens between two positions for taking either close-ups or distant shots.
- Image sensor: This is the light-detecting microchip in a digital camera and it uses either CCD or CMOS technology. You can’t actually see the chip in this photo, because it’s directly underneath the lens.
- USB connector: Attach a USB cable here and connect it to your computer to download the photos you’ve taken. To your computer, your camera looks like just another memory device (like a HDD).
- Secure Digital card slot (SD card): You can slide a flash memory card in here for storing more photos. The camera has a very small internal memory that will store photos too.
- Processor chip: The camera’s main digital “brain”. This controls all the camera’s functions. It’s an example of an integrated circuit.
Another important part, not shown here, is the LCD display that shows you the photos you’ve taken. It’s mounted on the back of the electronic circuit board so you can’t see it in this photo.