Week 1 - Introduction, Perception, Images and Lab fundamentals Flashcards
What is multimedia?
Interactive, computer meditated presentation that includes at least 2 of the following:
Text, sound, still graphic images, motion graphics, animation.
What are the primary functions of multimedia computers?
Development tools for multimedia creation - e.g. Adobe, Apple
Delivery devices for multimedia applications - Browsers or player applications
What are the past uses of multimedia?
Multimedia was mainly limited to instructional material - Computer assisted instruction (CAI), Computer assisted learning (CAL)
What are the uses of multimedia now?
Instruction
Entertainment
Scientific analysis, research and presentations
Business applications, advertising and sales
Art and other humanities purposes
Adaptive technologies for the disabled
Virtual reality
What is perception?
“The consciousness or awareness of objects or other data through the medium of the senses.”
List the electromagnetic spectrum from shortest to longest wavelength.
High energy -> Gamma rays, X-rays, Ultra-violet, Visible, Infra-red, Microwaves, TV, Radio Waves
What is the equation for wavelength?
c = f(lamda)
What is light usually measured in?
Radiance (watts) - Total amount of light emitted
Luminance (lumens) - Light strength that is perceived by the human eye
Brightness - Subjective measure of how bright an object appears to be
What is the wavelength of visible light?
400-700 nm
Purple - blue - green - yellow - orange - red
What are rods and how many do we have?
Light receptor cells that detect shades of black and white in the peripheral vision. Works well in the dark. We have roughly 120 million rods.
What are cones and how many do we have?
Light-receptor cells that are sensitive to colour located mainly in the centre and only work in bright light. Sensitive to 3 bands of electromagnetic radiation. We roughly have 6 -7 million rods.
What colours does the human eye respond to?
Humans are tri-chromatic and respond red, green and blue.
What is an active display?
A display that emits a combination of Red, Blue and green light. Emits different wavelengths of light.
What is a passive display?
Passive displays show colour by absorbing some wavelengths and reflecting others. Passive displays have Cyan, Magenta and Yellow (CMY) as the primary colours. Known as the subtractive colour system which absorbs RGB respectively.
How sensitive is the eye to different colours?
- 299 x Red
- 587 x Green
- 114 x Blue
What is a colour gamut?
A graph specifying the ranges of colour a particular display can produce
What are the models of colour the eye can respond to other than wavelengths?
Luminance or brightness - intensity (energy) of light
Excitation purity or saturation - how washed out or pure the colour is
Chromaticity or hue of light - purity and dominant frequency
What are the psychophysical models?
Based on human perception
HLS - Hue, Lightness, Saturation
What is saturation?
How much white light has been added to the colour, dominance of the hue - Excitation purity
What is hue?
Perceived dominant wavelength - What colour it is
What is the HSV colour colour model?
Saturation, hue, value
What is value of light?
Brightness - perceived intensity of light - how light/dark it is (Energy)
What is picture resolution?
Number of pixels or samples used to represent an image
What does a higher resolution mean?
Higher resolution the better quality the image/bitmap is
What does image resolution determine?
The quality and the storage requirements
What does aspect ratio represent?
Number of horizontal pixels x vertical pixels
How is data stored?
Data is stored using binary number which are either 1 or 0 an individual binary digit is referred to as a bit.
Advantages and disadvantages of true colour
High quality but requires more memory
Advantages and disadvantages of palette colour
Enables easier implementation of certain techniques but limited number of colours leading to lower quality
