Hi Everyone, Welcome back to Camera and Clicks.
When you see a beautiful flower, tree, a colorful landscape or something interesting what is it that you do ? Well as for me, I try to capture it with my camera, so is the case with many other amateur photographers. It’s not over with just taking a shot, we press the playback menu button and see the result and it’s perfect. A smile 😀 lights up on our face and we go on to our next subject.
The beauty of digital camera is, you can review your photos within seconds. If the photo is not perfect 😦 then there is always a second, third, forth, well many chances. Ever wondered what happens from the moment you press the shutter button till the moment you review your photo on the LCD screen of your camera. It’s just a second but a lot can happen in that time. This brings us to our topic this week ” How Digital Cameras Work “.Ok Ok people don’t run away I intend to keep it as simple as possible.
How Digital Cameras Work
When we press the shutter release button light travels through the lens and hits the image sensor. Two main types of image sensors mostly used are CCD (Charge-coupled Device) and CMOS (Complementary Metal-oxide Semiconductor). Of these CMOS is most widely used ranging from phone cameras to high end DSLRs. An image sensor is a silicon chip consisting of light sensitive sites known as “Photosites“.
The light that hits the photosites get converted to photons. High intensity light forms the bright area of the photo and dark areas of a photo are formed by low intensity light. These photosites do not cover the entire area of the sensor, they cover only half of the sensor or even less. Digital cameras use ” Microlens arrays ” to help photosites gather more light.
Our cameras sees the world in black and white. To add color to the photo, a color filter is placed in front of the sensor. Two most commonly used color filters are RGB color filters and CYMK color filters. RGB filter consists of red and green color filters in one row and green and blue filters in the next row. The number of green filters are more than red and blue, this is because our human eyes are more sensitive to different shades of green. This type of filter pattern is known as ‘Bayer pattern’ named after Bryce Bayer, a Kodak scientist.
On the other hand CYMK filters are more complex than RGB filters. It uses complementary colors – Cyan, Yellow, Magenta and Black. The CYMK filter is combined with green filter to form CYMG filter and the other primary colors are subtracted. This technology is mostly used in printers and also in sensors which are sensitive to low light conditions.
The data obtained so far is still in analog form. To convert the data into digital form a Analog to Digital Converter ( ADC) is used. Now the camera has all the color information it requires the next step that occurs is Demosaicing ( also known as De- Mosaicing). This is a process in which all the color information bits obtained from the image sensor are combined to form full image.
The data so obtained gets some retouching like sharpness, contrast, aliasing, etc.. This image now is compressed and sent to temporary storage area known as Buffer. Buffer capacity is important. The higher the buffer capacity the more number of photos you can take per second. Well the buffer capacity is full the images are transferred to the memory card. These images are what you see when you press the playback button.
That’s it for now. I tried to make it as simple as possible. Let me know if it’s too technical. Next time lets look into how this data will help us in photography