imaging and display

Question 1

What are the three core elements involved in image formation?

Answer 1

Geometry, Light, and Colour.

Question 2

What does the pinhole camera model represent?

Answer 2

A simple imaging system where light enters through a small hole and projects onto an image plane.

Question 3

What is the ‘optical centre’ in the pinhole model?

Answer 3

The single point where all incoming light rays converge — also called the centre of projection.

Question 4

What is an aperture in the context of imaging?

Answer 4

The opening that allows light to enter the imaging system.

Question 5

What happens when the aperture in a pinhole camera is too small?

Answer 5

Less light enters, making the image dark, and diffraction causes blurring.

Question 6

What happens when the aperture is too large?

Answer 6

Multiple rays enter from each point in the scene, causing image blur.

Question 7

What is diffraction?

Answer 7

The bending and spreading of light when it passes through a small opening or around an obstacle.

Question 8

Why are lenses used in modern cameras instead of pinholes?

Answer 8

Lenses focus more light accurately onto the sensor, producing brighter and sharper images.

Question 9

What does a lens do to incoming parallel light rays?

Answer 9

It focuses them onto a single focal point behind the lens.

Question 10

What determines the focal length of a lens?

Answer 10

The shape of the lens and its index of refraction.

Question 11

What is the lens equation?

Answer 11

1/f = 1/u + 1/v, where f is focal length, u is object distance, and v is image distance.

Question 12

What is the ‘circle of confusion’?

Answer 12

A blurred spot caused when light rays do not converge perfectly on the image sensor.

Question 13

What is the role of the sensor array in digital cameras?

Answer 13

To detect photons and convert them into electrical signals, forming a digital image.

Question 14

What does each sensor cell in a digital camera record?

Answer 14

The amount of light (intensity) falling on it from a small angular range.

Question 15

What does CCD stand for?

Answer 15

Charge-Coupled Device.

Question 16

What does CMOS stand for?

Answer 16

Complementary Metal-Oxide-Semiconductor.

Question 17

How is a CCD sensor read out?

Answer 17

Pixels are read out serially, one at a time.

Question 18

How is a CMOS sensor read out?

Answer 18

Each pixel has its own amplifier, allowing faster and parallel read-out.

Question 19

Which type of sensor is more common in smartphones today?

Answer 19

CMOS sensors.

Question 20

What are active display technologies?

Answer 20

Displays that emit or manipulate light directly, like LCD, OLED, and DLP.

Question 21

What are passive display technologies?

Answer 21

Displays that do not emit light, like printed paper using laser or inkjet printers.

Question 22

What principle does an LCD use to control light?

Answer 22

Liquid crystals twist the polarization of light depending on applied voltage.

Question 23

What happens in an LCD when voltage is applied?

Answer 23

The crystals align with the electric field, blocking light.

Question 24

What happens in an LCD when no voltage is applied?

Answer 24

Crystals align with each other, twisting light and allowing it to pass.

Question 25

How do LCDs produce colour?

Answer 25

By placing RGB filters over pixels or using separate panels in projectors.

Question 26

What is OLED short for?

Answer 26

Organic Light Emitting Diode.

Question 27

What’s a key advantage of OLED over LCD?

Answer 27

Each pixel emits its own light, allowing deeper blacks and higher contrast.

Question 28

What was the earliest surviving photograph?

Answer 28

A photo by Niépce in 1826 using an 8-hour exposure.

Question 29

What was the daguerreotype process?

Answer 29

A photographic method from 1839 that used metal plates and allowed no copies.

Question 30

What improvement did the calotype introduce?

Answer 30

It used paper negatives, enabling multiple copies of a photograph.

Question 31

When did digital photography become widespread?

Answer 31

In the late 1990s.

Question 32

By 2014, what device had overtaken all other camera types?

Answer 32

Smartphones, which outsold all previous cameras combined in the prior 15 years.

Question 33

How does digital photography differ from traditional photography?

Answer 33

It uses electronic sensors to capture and store images instead of chemical film.

Question 34

What is the role of a display in visual computing?

Answer 34

To render digital images into visible light for human perception.

Question 35

What is the fundamental goal of image formation?

Answer 35

To convert 3D scenes into accurate and interpretable 2D representations.

Question 36

What is meant by dimensionality reduction in imaging?

Answer 36

The process of mapping a 3D scene onto a 2D plane while preserving useful information.

Question 37

Why can projection in imaging be tricky?

Answer 37

Because it can introduce distortions or visual illusions based on perspective.

Question 38

What’s the main challenge with direct sensor exposure to a scene?

Answer 38

Light from multiple parts of the object overlaps on the sensor, causing blur.