Computer Graphics

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Computer Graphics
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Not a new idea

• The Basilica of St. Sophia, in Turkey.
• Built by Constantine the Great and reconstructed
  by Justinian in the 6th century.
• Its immense dome rises 55 meters above the ground
  and its diameter spans 31 meters.
• Walls are covered in MOSAICS

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Mosaics

• Mosaics are pictures made up of tiny chips of
  glass or ceramic tile.
• The smaller the chips of tile, the more of them
  there will be, and the clearer the image.
• The more colours available for the tile chips,
  the better the final image looks.

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Computer images?

• Computers create images based on exactly the same
  principle
• Lots of chips of colour called PIXELS.
• The more Pixels, the clearer the image.
• The more colours, the better the image looks.

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Tiny Little Pixels
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Resolution
The more pixels, the clearer the picture gets
and the smaller the pixels become.
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Resolution
Till eventually you cant even tell the picture
is made up of dots...
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Colour depth

• Colour photos are made of many colours.
• The more colours, the more realistic they look.
• This 24 bit image contains a possible 16,777,216
  colours.

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Colour depth

• For example, this pixel may have the value
  000010000011001100011011

• This binary code represents a colour value
  between 0 and 16,777,215.
• This is because 224 is 16,777,216.

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Colour depth
8 bit/pixel 256 colours
24 bit/pixel 16, 777,216 colours

• 4 bit/pixel 16 colours

1 bit/pixel 2 colours (b/w)
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Calculating size

• 320 x 240 pixels
• 24 bits/pixel
• So how many bits are needed to represent this
  image in a computers memory?
• 320 x 240 x 24 1,843,200
• To convert to Kbytes Divide by 8, then divide by
  1024
• 225 Kb
• and sure enough...

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Calculating size