Representing Images

• How many colours in a standard RGB display?

  16.7 million
• Define a pixel

  The smallest unit of an image
• Define metadata

  Data about data
• What is the difference between digital and analogue data?

  Anything that is digital is 1s and 0s (binary) wheres anything analogue is data that exists in reality.
• What is a bitmap image?

  A grid of pixels where each pixel is given a binary code that translates to a colour value
• What is a raster graphic?

  A bitmap
• Define resolution

  The number of pixels used to make up a bitmap image
• Why is there deterioration in quality when a bitmap is resized?

  The size of each pixel grows or shrinks to maintain the resolution of the image
• What is bit depth / colour depth?

  The number of bits used to store the colour of each pixel
• How to calculate file size of an image?

  Number of pixels x bit depth
• Define a vector graphic

  A vector graphic can be represented as a list of objects or drawing commands
• Give examples of properties of objects (vector)

  Dimensions (width, height)

  Positions (x/y coordinates)

  Appearance(fill colour, outline, stroke width)
• What does resolution independent mean?

  Resolution independent means that an image can be resized to any scale without losing quality.
• Advantages of vector

  Resolution independent

  Less storage space than bitmap

  No loss of clarity

  Good for logos
• Disadvantage of vector

  Not good for photographs
• Advantages of bitmap

  Good for photographs

  Easy conversion to different formats
• Disadvantages of bitmap

  Resolution dependent

  Image can become pixelated when you rescale