Digital camera - part 2

Digitizing information
Light is converted to electrical charge. However, electrical charges are not in digital signal. Thus, the signal must be passed through analog-to-digital converter(ADC). Photons of light hit the photosites, thus accumulating electrical charges. Then the ADC measures the amt which is considered analog info. It then converts to the binary info.

Photosites and Pixels
"A camera claims to be a 2.1-megapixel camera and it is capable of producing images with a resolution of 1600x1200. Let's do the math: a 1600x1200 image contains 1,920,000 pixels."
Well, this is the camera indeed has 2.1 million photosites on the CCD, just that some of the photosites aren't used for imaging. Since CCD is an analog device, some sort of circuitry(dyed black so doesn't absorb light) is needed to connect to the ADC so that it can measure the amt of charges.

These are egs of storage systems used in digital cameras:

• Built-in memory- built-in flash memory
• SmartMedia card
• CompactFlash
• Memory Stick
• Floppy disk
• Hard disk
• Writeable CD and DVD

The two main file formats used by digital cameras are TIFF and JPEG. TIFF is an uncompressed format and JPEG is a compressed format. Most cameras use the JPEG file format for storing pictures, and they sometimes offer quality settings (such as medium or high).

Compression

Some of the patterns repeat over again in a picture, like the blue sky... thus digicam makes use of repeated pattern to create exactly the same effect and this is known as repetition.

Some compression throw away certain meaningless data. Thus lower the resolution, more data is thrown out. This is known as irrelevancy.

Controlling Light

The word camera comes from the term camera obscura. Camera meaning room or chamber and obscura meaning dark. Thus camera means dark room. It is crucial to control the amt of light entering because if too much light enters, some info would be lostbecasue the sensor cannot hold any more of the light.

Aperture is the small opening found in the camera and is located at the back of the lens. On a very bright day, the light reflected off your image may be very intense, thus a small aperture is needed. Likewise, if it is a cloudy day, aperture should be enlarged to produce a brighter image. Interestingly, this works out to be the same as the pupil of our eye. Our pupil tends to dilate when we are in a dark room and shrink when we are under the sun.

Shutter speed

Basically, it means the amt of time light is allowed to enter the aperture. Film-based camera has mechanical shutter. So if u expose ur film, it can't be wiped clean again. However, the sensor in a digital camera can be easily resetted every time and it is called digital shutter.