Image representation - 87 - 91 Flashcards

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1
Q

how can images in computers be stored

A

as bitmaps or vectors

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2
Q

difference between bitmaps and vectors

A
  • bitmaps use single discrete, individual pixels of colour, which make up image
  • whereas a vector uses lists of information and mathematical equations to draw an image based on the data
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3
Q

how to calculate size of image in pixels

A

width in pixels x height in pixels

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4
Q

what is a pixel

A

every dot of colour in the image

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5
Q

what is resolution

A

width in pixels x height in pixels / number of dots per inch, where a dot is a pixel
- measured in pixels per inch

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6
Q

what is colour depth

A

number of bits stored for each
pixel.
- n bits gives 2^n combinations

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7
Q

How many bits are usually in modern images?

A

24

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8
Q

how to calculate storage requirement for bitmaps

A

height in pixels x width in pixels x colour depth

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9
Q

relationship between the quality, colour depth, and file size

A

as the quality and colour depth of an image increases, its file size increases

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10
Q

what is metadata

A

data about data
- is stored along with the actual bits which make up the image and increase the overall file size

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11
Q

examples of metadata

A
  • dimensions
  • colour depth
  • width and height in pixels
  • location
  • creation date
  • file name
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12
Q

examples of information needed to draw a vector image

A
  • fill colour
  • radius
  • outline colour and width
  • coordinates
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13
Q

advantages of vector graphics

A
  • file size is kept relatively smalll, regardless of how much you scale the image
  • will always scale without loss of quality
  • good format for logos and images with simple shapes and colours
  • they transmit faster and load quickly
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14
Q

disadvantages of vector graphics

A
  • cannot easily replicate an image with continuous areas of changing colours
  • individual pixels cannot be chabged
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15
Q

advantages of bitmapped graphics

A
  • great format for storing full colour images taken on a phone or digital cameraas they can deal with images that have continuous areas of changing colour
  • can manipulate individual pixels easily
  • images can easily be altered or retouched
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16
Q

disadvantages of bitmapped graphics

A
  • generally take up more memory and file storage
  • images don’t scale very well, they become pixelated the larger they get
17
Q

describe how a vector graphic is represented

A
  • image is represented as object
  • properties of objects are stored
  • a property is given, eg fill colour