Images and Sound 1.2 Flashcards

1
Q

types of image files - bitmap

A

BMP

JPG

GIF

PNG

TIFF

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2
Q

types of image files - vector

A

SVG

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3
Q

Bitmap images

A

-made from pixels

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4
Q

pixel is given

A
  • a colour
    -binary number which represents that colour
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5
Q

image resolution

A

the concentration of pixels within a
specific area

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6
Q

Increasing the number of colours in bitmap

A

More bits per pixel =
more colour combinations

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7
Q

bit depth

A

number of colours

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8
Q

higher bit depth

A

better variety of colours

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9
Q

bit depth formula

A

2 to the power of n
n = bits

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10
Q

size of a bitmap image

A

measured in pixels (width x height).

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11
Q

colours in pixel

A

Each pixel has a proportion
of red, green and blue
-makes one colour

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12
Q

colour values

A

expressed in
software as denary RGB values and in hexadecimal

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13
Q

metadata

A

Colour depth in bits per pixel

Resolution (Height and width in pixels)

Date created

Author

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14
Q

pros of colour values being in hex

A

-easier to read/write = reduces errors

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15
Q

RGB value range

A

-0 to 255
-each colour must be 8 bits to store range

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16
Q

entire pixel bit range

A

3 * 8 = 24 bits

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17
Q

transparency channel

A

-32 bits per pixel 8 bits are given
-allow a background to show through

18
Q

image size in bits

A

width * height * colour depth

19
Q

image size in bytes

A

(width * height * colour depth) /8

20
Q

analogue sound signals are

A

continuous

21
Q

Digital signals are

22
Q

how is Sound digitized

A

by repeatedly measuring and
recording the sound wave

23
Q

A to D converters

A

Sounds is converted to a digital form
= stored + processed by a computer

24
Q

An Analogue to Digital Convertor (ADC)

A

is used to
convert inputs to digital signals

25
A Digital to Audio Convertor (DAC)
is used to convert digital signals to outputs
26
sound sampling
measurement of amplitude of a sound wave at a given time
27
how is sound sampled
-sample resolution (bit depth) -sampling rate
28
sampling rate
number of samples taken per second (Hz)
29
Sample resolution
The number of bits used to record each measurement
30
More bits used per sample =
- the height of the wave to be more accurately measured - increases file size
31
Hertz
1Hz = 1 sample per second
32
sampling rate frequency
The greater the frequency, the greater the accuracy, and file size
33
Calculating sound file sizes
sample rate x bit depth x duration
34
Recording quality improves:
the more frequent the more accurately recorded the wave height
35
Increasing the sampling rate (frequency) =
means recording more data points
36
Increasing the bit-rate =
improves the accuracy of each data point
37
Lossy compression
removes sounds that we can’t easily hear or that is unecessary
38
Lossy compression cons
-leaves out some data =affects quality
39
Lossy compression pros
useful for storing, downloading or streaming -as it is smaller
40
Lossless compression
-reduce the file size when compressed but do not lose any information -can be decompressed
41
eg of lossless
FLAC (Free Lossless Audio Codec) ALAC (Apple Lossless Audio Codec) WMA Lossless (Windows Media Audio)