Point Processing

Question 1

Difference in values per pixel?

Answer 1

Coloured pixels - 3 values per pixel (red intensity, green intensity, blue intensity)

Monochrome pixels - 1 value per pixel (intensity)

Question 2

What are pixels?

Answer 2

Pixels are small squares of single solid colour (or shade if monochrome) that make a grid to create images.

Question 3

How does the human visual system work?

Answer 3

The eye has 3 types of cone photoreceptors sensitive to red, green and blue light.

The brain transforms RGB into separate brightness and colour channels (e.g.LHS).

Question 4

What it point processing?

Answer 4

‘Point’ relates to pixels

Point processing adjusts a pixel’s value according to a transformation function usually for the purpose of improving the perceived image quality.

The transformation is independent of the values of the neighbouring pixels.

Question 5

What are the typical adjustments made to photos?

Answer 5

Brightness and contrast adjustment

Gamma correction

Histogram equalisation

Colour correction.

Question 6

What should be considered when determining the quality of an image?

Answer 6

The image histogram.

The histogram simply records the number of pixels within an mage at each light intensity value and is displayed as a bar chart.

Question 7

Look up table

Answer 7

A look up table (LUT) implements a functional mapping of pixel intensity values.
To remap the intensity values of an input image I, to the output image, J.