A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. Digital camera has a sensor that converts light into electrical charges. The image sensor employed by most digital cameras is a charge coupled device (CCD). Some cameras use complementary metal oxide semiconductor (CMOS) technology instead.
Once the sensor converts the light into electrons, it read the value ( accumulated charge) of each cell in the image. A CCD transports the charge across the chip and reads it at one corner of the array. An analog-to-digital converter (ADC) then turns each pixel's value into a digital value by measuring the amount of charge at each photosite and converting that measurement to binary form. The amount of detail that the camera can capture is called the resolution and it is measured in pixels. The more pixels a camera has the more detail it can capture and the larger pictures can be without becoming blurry.
Just as with film, a digital camera has to control the amount of light that reaches the light sensor. The two components it uses to do this are the aperture and shutter speed, are also present on conventional cameras.
Aperture: The size of the opening in the camera. the aperture is automatic in most digital cameras but some allow manual adjustment to give professionals and hobbyists more control over the final stage.
Shutter Speed: The amount of time that light pass through the aperture. Unlike film, the light sensor in a digital camera can be reset electronically so digital cameras have a digital shutter rather than a mechanical shutter.
These two aspects work together to capture the amount of light needed to make a good image. In addition to control the amount of light, the camera has to adjust the lenses to control how the light focused on the sensor.
The focal length is the distance between the lens and the surface of the sensor.
With digital zoom, camera takes pixels from the center of the image sensor and interpolate them to make a full sized image. Depending on the resolution of the image and sensor, this approach may create a grainy or fuzzy image. you can manually do the same thing with image processing software--simply snap a picture, cut out the center and magnify it.
Steps:
1. You aim the camera at the subject and adjust the optical zoom to get closer or farther away.
2. You press lightly on the shutter release.
3. The camera automatically focuses on the subject and takes a reading of the available light.
4. The camera sets the aperture and shutter speed for optimal exposure.
5. You press the shutter release all the way.
6. The camera resets the CCD and exposes it to the light, building up an electrical charge, until the shutter closes.
7. The ADC measures the charge and creates a digital signal that represents the values of the charge at each pixel.
8. A processor interpolates the data from the different pixels to create natural color. On many cameras, it is possible to see the output on the LCD at this stage.
9. The information is stored in some form of memory device.
