Digital Photography

1
Digital Photography

• A2 Graphics

2
Introduction

• Digital cameras work by converting light into
  electrical charges. There are two types of
  sensor
• Charge coupled device (CCD) for high quality
  cameras.
• Complementary metal oxide semi-conductor (CMOS)
  for more basic models.

3
How Does it Work?

• Light sensitive diodes called photosites convert
  light (photons) into an electrical charge
  (electrons).
• Brighter light generates a higher electric
  charge.
• The electrical charge is converted from analogue
  to digital signals.

4
Colour

• The light needs to be filtered into the three
  primary colours.
• This is done using permanent filters positioned
  over each individual photosite.
• More green pixels are required to create an image
  that will be perceived as true colour by the
  human eye.
• Four separate pixels determine the colour of one
  pixel forming a mosaic.

5
Memory

• Digital images require memory this needs to be
  compressed.
• This can be done in two ways
• Repetition identifying repetition of colour
  patterns within a digital image. Reduces the
  file by 50.
• Irrelevancy any information that is
  undetectable by the human eye is discarded.

6

• Digital cameras store images internally, often
  using removable memory cards or sticks.
• They use adjustable apertures and shutter speeds
  in more expensive cameras.
• This controls the amount of light reaching the
  film.