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Lecture 3

Computer Science 1033A/B Lecture Notes - Lecture 3: Cmyk Color Model, Laser Printing, Pixelation


Department
Computer Science
Course Code
COMPSCI 1033A/B
Professor
Vivi Tryphonopolous
Lecture
3

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Lecture
3
What is
digitization?
Refers
to the
process
of translating a piece of
information
into
bits
Bits= binary
digits
Fundamental units of
information
in a computer system
("0"
and
"1"
)
Electric
signals
translate into "bits" ("0" and
"1"
)
1
Byte = 8
bits
x
bits=#
of digits,y
values=#
of combinations
ex:
2
4 {4
bit)=
16
values,:.
x=4,y=16
an image is represented by a grid (array,matrix) of
squares
called pixels (Picture Elements)
pixel= the smallest image component
D
:.
shows smallest
detail
arranged in columns and
rows
each pixel is given a numerical value that represents the corresponding
colour
Colour Coding
range of colours
D
associated
with number of
bits
if a pixel colour is represented by
1bit
only {O=black,1=white)
D
:.
1bit
allows for
2
colours
Rule
:
more bits=more
shades
{colours)
In true colour each pixel represents same colour shade
Colour
Models
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o
Additive
model (RGB)
Primary
colours= red,
green,
blue
Adding light to black
background (monitor)
in order
to obtain
colour
shades
Used for
Printing:
o Subtractive model (CYMK)
Cyan
,
magenta,
yellow
Ink when
applied
removes
("subtracts")
from a white
background
RGBCode
Each
pixel is
represented
by three values
(R,
G,
B)
Syntax
Each
value ranges from
0-255
0 = no
colour,255
= max
amount
256 colour shades =
1
8
bits
Need 3 bytes for true colour (8
bits=
1
byte)
RGB
Code:<0-255,0-255,Q-255>
{black=
<0,0,0>,white
=
<255,255,255>)
The human eye can detect about 10
million colours
Types of
Graphics
Affects how the graphics are
displayed
on a
computer screen:
1.
Quality
2. File Size
3. Time
to
display
graphics
Bitmap
Graphics
Also known as
RASTER
graphics
Made up of
pixels
Editing
pixels=
changing
colour,shade
and
brightness
If you start
with
a small image & make
it
larger by
resizing
...
squares become larger,edges more jagged
]--
quality
decreases
pixelation
file size
increases
Vector
Graphics
Image
represented with
lines and arcs that have a
mathematical relationship
which
describes
the
drawing
of the
shape
It
doesn't
matter
what size the image
is
As the image is resized
larger/smaller...
Edges
still
clean,crisp
No
distortion
going
up/down
in size
Quality
is
maintained
File size increases {if resized
larger)
Graphic
Software
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