G491 1.1 - Imaging and Signalling

Question 1

Pixel

Answer 1

Digital images are made up of pixels. A pixel represents the value of an individual square of the image, and it has a value assigned to it. The total number of pixels in an image is the number of pixels across multiplied by number of pixels down.

Question 2

Bit

Answer 2

A bit is a datum with a value of either 0 or 1.
The more values a pixel can take on, the more bits must be used to represent its value.
The number of values (N) that a pixel represented by I bits can take on is given by the formula: N = 2I. Hence: I = LogN/Log2.
Amount of information in an image (bits) = number of pixels x bits per pixel.

Question 3

Byte

Answer 3

A byte is equal to 8 bits

Question 4

Focal length

Answer 4

x

Question 5

Optical power

Answer 5

x

Question 6

Magnification

Answer 6

x

Question 7

Resolution

Answer 7

x

Question 8

Sampling

Answer 8

x

Question 9

Spectrum

Answer 9

x

Question 10

Signalling

Answer 10

x

Question 11

Bandwidth

Answer 11

Bandwidth is the frequency of a signal.
Since bandwidth is a frequency, it is the number of bits per second.
The bandwidth required to transmit a signal accurately can be calculated by using 1 as the number of bits, giving the formula: B = 1/t, where B is bandwidth (in Hz), and t is the time taken to transmit 1 bit of data (in s).
The bandwidth of a signal regulates the bit rate of the signal, as, with a higher frequency, more information can be transmitted.
This give us the formula (similar to the formula for lossless digital sampling): b = 2B where b is the bit rate (in bits per. second), and B is the bandwidth (in Hz).

Question 12

Noise

Answer 12

x

Question 13

Polarisation

Answer 13

x

Question 14

Refractive index

Answer 14

The ratio of speed of light in vacuum to the speed of light in material of lens