Image Capture and Display Flashcards
What are the different types of waves?
- Radio Wave.
- Microwave.
- Infrared.
- Visible Light.
- Ultra Violet.
- X-Ray.
- Gamma Ray.
What does light provide?
- Energy possible to record an image.
- Makes vision possible.
How does light change throughout the image making process?
- In camera = wave length.
2. Digital image = particle.
What does a camera lens do?
Shapes the light entering into an image.
What do converging and diverging lenses do?
Converging = brings light together used in a camera.
Diverging = bends light away from a common point to create a virtual image.
What is the function of an image sensor?
Senses light and converts into a form that can be recorded.
Detects colour - light causes change in electrical charge.
What are the issues with glass lenses?
- Dispersion.
- Different colours don’t bend equally.
- Doesn’t focus light well.
What is “focal length”?
Distance from lens focal point - primary means of describing lenses.
What is the f number?
Ratio of focal length to diameter of aperture where light enters the camera.
What does the f number determine?
Blurriness and Brightness.
What is the “depth of field”?
Distance infant and beyond an object.
What does a higher f number result in?
High depth of field.
Both foreground and background are in focus.
What does a lower f number result in?
Blurring.
More depth to the photograph.
Sometimes referred to as “fast optics” due to it having fast exposure.
What is meant by dark noise?
Fluctuation in count values can be caused by electrons generated by warmth.
Explain quantisation noise.
- The mapping of a range of analogue voltage to a single value.
- Ruler used to measure electrons.
What is signal to noise ratio?
Strength of light compared to fluctuation caused by noise.
What is an LCD?
- 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.
What are the functions of LCDs?
- Used for displays in notebooks and other smaller computers.
- Allow the display to be a lot thinner.
What are the pros and cons of LCDs?
Pros: Low energy, small footprint, portable.
Cons: Viewing angle, non-uniform colours, backlight leakages.
What is the “depth of field”?
Distance infant and beyond an object.
What does a higher f number result in?
High depth of field.
Both foreground and background are in focus.
What does a lower f number result in?
Blurring.
More depth to the photograph.
Sometimes referred to as “fast optics” due to it having fast exposure.
What is meant by dark noise?
Fluctuation in count values can be caused by electrons generated by warmth.
Explain quantisation noise.
- The mapping of a range of analogue voltage to a single value.
- Ruler used to measure electrons.
What is signal to noise ratio?
Strength of light compared to fluctuation caused by noise.
What is an LCD?
- 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.
What are the functions of LCDs?
- Used for displays in notebooks and other smaller computers.
- Allow the display to be a lot thinner.
What are the pros and cons of LCDs?
Pros: Low energy, small footprint, portable.
Cons: Viewing angle, non-uniform colours, backlight leakages.
How do liquid crystal displays work?
- 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.
