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computer science - Coggle Diagram
computer science
Images
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Each pixel is a single colour and is given a binary value which represents that colour e.g. 11000000 might equal Red
A pixel’s colour can be changed by changing this value
Resolution is the concentration of pixels within a specific area
The area is defined by the image width and height in pixels e.g. 3264x2448
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The number of combinations (2n) dictates the bit depth and therefore the number of colours that can be represented
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16 bits per pixel = 216 = 65,536 colours
24 bits per pixel = 224 = 16,777,216 colours
Sound
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Compression
Lossy compression removes the sounds in the frequency ranges that we can’t so easily hear or that least affect the perceived playback quality
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Lossless compression leaves out repeated data and instead makes a note of how many times it is repeated
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ASCII
character set
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Every computer storing letters using numbers needs to use the same code or it won’t make sense - we have to agree on a standard way of doing things.
This standard code is called a “Character Set” as it has a set of characters (letters, symbols etc.) each with their own number
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ASCII (American Standard Code for Information Interchange) has become the standard code, used worldwide
Numerous different codes for representing characters have been invented, but ASCII is commonly used nowadays on PCs
Originally only 7 bits were used but now the eighth bit is used to give extra characters such as ©, ® etc
Computer science
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Mostly used with sound, image and video file types
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Lossy compression (JPG, GIF, MP3)
Lossless compression (PNG, TIF, SVG)
Lossy Compression
Tries to reconstruct an image without the missing data
Much smaller file sizes but some loss of quality
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