Sampling and Quantization

Question 1

What are the two things that can be sampled in an image

Answer 1

Space and amplitude

Question 2

Define what can be represented in amplitude

Answer 2

Amplitude can represent the level of light

white to grey, this sample is then quantized.

Question 3

Describe a good quality image in terms of sampling

Answer 3

dense sampling and a fine level of quantisation

Question 4

Describe how pixels represent images

Answer 4

SIZE - The quality of the image can be detrimined by the amount (and size) of pixels. However this requires a large amount of memory.

BITS - the amount of values in grey scale a single pixel can represent. i.e 8 bits can represent 2^8 (256) different grey scale values;

Question 5

How are colours images represented

Answer 5

RGB colour images are where each pixel has 3 channels - red, green, blue. Some high qualities images are 3 seperate images others are merged into one.

Question 6

High quantisation of space leads to…

Answer 6

lots of pixels and therefore smooth lines. It also allows for details to be captured in text and texture.

Question 7

High quantisation of the amplitude

Answer 7

Amplitude refers to the quantisation of grey scale values. low quality can create false contours.

Question 8

Describe how videos are represented

Answer 8

Multiple images in frames (3 for RGB images).

These are represented as a series of 2D arrays.

Resolutions are determined by the amplitude (grey scale values) and space (pixels)

Question 9

Describe how saturation can effect sampling

Answer 9

If you have high saturation - (that is very bright areas with subtle differences). and a low amplitude. Then this will create a bad quality image.