Image Capture and Display

Question 1

What are the different types of waves?

Answer 1

1. Radio Wave.
2. Microwave.
3. Infrared.
4. Visible Light.
5. Ultra Violet.
6. X-Ray.
7. Gamma Ray.

Question 2

What does light provide?

Answer 2

• Energy possible to record an image.

- Makes vision possible.

Question 3

How does light change throughout the image making process?

Answer 3

1. In camera = wave length.

2. Digital image = particle.

Question 4

What does a camera lens do?

Answer 4

Shapes the light entering into an image.

Question 5

What do converging and diverging lenses do?

Answer 5

Converging = brings light together used in a camera.

Diverging = bends light away from a common point to create a virtual image.

Question 6

What is the function of an image sensor?

Answer 6

Senses light and converts into a form that can be recorded.

Detects colour - light causes change in electrical charge.

Question 7

What are the issues with glass lenses?

Answer 7

1. Dispersion.
2. Different colours don’t bend equally.
3. Doesn’t focus light well.

Question 8

What is “focal length”?

Answer 8

Distance from lens focal point - primary means of describing lenses.

Question 9

What is the f number?

Answer 9

Ratio of focal length to diameter of aperture where light enters the camera.

Question 10

What does the f number determine?

Answer 10

Blurriness and Brightness.

Question 11

What is the “depth of field”?

Answer 11

Distance infant and beyond an object.

Question 12

What does a higher f number result in?

Answer 12

High depth of field.

Both foreground and background are in focus.

Question 13

What does a lower f number result in?

Answer 13

Blurring.
More depth to the photograph.
Sometimes referred to as “fast optics” due to it having fast exposure.

Question 14

What is meant by dark noise?

Answer 14

Fluctuation in count values can be caused by electrons generated by warmth.

Question 15

Explain quantisation noise.

Answer 15

• The mapping of a range of analogue voltage to a single value.
• Ruler used to measure electrons.

Question 16

What is signal to noise ratio?

Answer 16

Strength of light compared to fluctuation caused by noise.

Question 17

What is an LCD?

Answer 17

• Liquid crystal display.
• Controls light getting through by polarisation.
• 2 filters twist plane of polarisation.
• 90 degrees is on = light.
• 0 degrees is off = no light.

Question 18

What are the functions of LCDs?

Answer 18

• Used for displays in notebooks and other smaller computers.
• Allow the display to be a lot thinner.

Question 19

What are the pros and cons of LCDs?

Answer 19

Pros: Low energy, small footprint, portable.
Cons: Viewing angle, non-uniform colours, backlight leakages.

Question 20

What is the “depth of field”?

Answer 20

Distance infant and beyond an object.

Question 21

What does a higher f number result in?

Answer 21

High depth of field.

Both foreground and background are in focus.

Question 22

What does a lower f number result in?

Answer 22

Blurring.
More depth to the photograph.
Sometimes referred to as “fast optics” due to it having fast exposure.

Question 23

What is meant by dark noise?

Answer 23

Fluctuation in count values can be caused by electrons generated by warmth.

Question 24

Explain quantisation noise.

Answer 24

• The mapping of a range of analogue voltage to a single value.
• Ruler used to measure electrons.

Question 25

What is signal to noise ratio?

Answer 25

Strength of light compared to fluctuation caused by noise.

Question 26

What is an LCD?

Answer 26

• Liquid crystal display.
• Controls light getting through by polarisation.
• 2 filters twist plane of polarisation.
• 90 degrees is on = light.
• 0 degrees is off = no light.

Question 27

What are the functions of LCDs?

Answer 27

• Used for displays in notebooks and other smaller computers.
• Allow the display to be a lot thinner.

Question 28

What are the pros and cons of LCDs?

Answer 28

Pros: Low energy, small footprint, portable.
Cons: Viewing angle, non-uniform colours, backlight leakages.

Question 29

How do liquid crystal displays work?

Answer 29

• Liquid crystals are forced to twist into a predictable patter - by horizontally etched glass in the rear and the vertically etched glass in the front.
• Light passes through the liquid crystals and naturally follows this pattern.
• Enters through the horizontal plane and exits through the vertical plane.
• By passing electricity through them we can get the molecules to align themselves with the electric flow.
• Causing light to no longer twist when passing through.
• By adjusting the amount of electricity that flows through each set of electrodes we control how much light reaches each colour filter and therefore what colour filter is seen on the display.
• The electricity flowing through each crystal is changed one by one and row by row sixty times per second to build the full picture.