Transcript Boardworks Rep images and sounds

2.5 Representing images
and sounds
Unit 2 Digital Media
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Curriculum
This presentation
supports the links
following sections
of the Programme of Study for KS3 Computing:
understand how instructions are stored and executed within a
computer system; understand how data of various types
(including text, sounds and pictures) can be represented and
manipulated digitally, in the form of binary digits
This presentation supports the following areas of knowledge
in the Naace Curriculum Framework for KS3 ICT:
Technical Understanding – Programming and control
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Learning objectives
By the end of this presentation we will have learned:
how images are represented in binary
how metadata is used in image files
how colour depth and resolution affect file size
how sound is stored in digital form
what affects the size and quality of an audio file
what can be done with image and sound data after
it has been digitized.
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Representation of sound
Like colour, sound is not digital but analogue. However, to
be stored by a computer it must be in a digital format.
While analogue signals can have any value, digital signals
must store data using only the values 0 and 1.
How could you store analogue sound waves like
the ones above using binary?
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Sampling
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File size
What factors do you think affect the size and quality of
a sound file?
The higher the sample rate, the higher the sound quality
will be. The file size will also be larger because more
samples require more storage space.
Even at a relatively low sample size,
uncompressed digital music files
stored in RAW format are often very
large. Compression reduces the
size of the files by applying
algorithms and codecs to store
repeated patterns in the data.
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After digitizing
After the data has been digitized, the computer is able to:
work with the data to display a picture, play a sound or
calculate new values and new data
store the data on other devices, hard drives and
memory sticks and display stored data on the screen
use specialist software to edit the sound or image
share the data with others through email, WiFi or Bluetooth
copy or back up the data.
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