Computer Graphics
Definition –
Computer Graphics is the
study of techniques to improve communication between human and machine. E.g Pictures,
Graphs, sketches are to be drawn with the help of computer.
Components of
Computer Graphics System
There are three components
of computer graphics
Graphically components of
graphics system are illustrated below;
Pixel
/ Points
·
Line generally made up of points.
·
If Points are in greater quality its high resolution.
·
Points must be of same size. That point is nothing
but Pixel.
·
The pixel is the smallest addressable screen
element.
·
Smallest piece of display screen which is controllable.
·
Pixel has name and address.
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The array, which contains an internal
representation of the image, is called the Frame Buffer.
Interacting Devices
(1) Keyboard
Keyboard is one of the most important used in the computer graphics. Keyboard is input devices in which various labeled button are
available for different operations by pressing combination of it. Keyboard is
commonly used input device today.
There are various types of keyboard are available in market.
Most of the companies self manufacture keyboards as per their different
purpose. A QWERTY keyboard that means 101 labeled keyboards is more
popular among that.
Fig. : QWERTY keyboard
Body of the QWERTY keyboard is classified into some specific
keypad set.
Editing keys set:
Because of this keyset of alphabetical this type of keyboard is known as QWERTY
keyboard. It includes all alphabets starting from Q, W, E,…. (Shown in fig.
3.2), numbers 1,2,3, …9, 0, arithmetic buttons (+,-,+,/), all punctuation marks
buttons (!, ?, “, ‘ etc)
Numeric Keys set: There
are separate numeric keys set are available especially for the calculation
purpose.
Function keys and
other operational keys set: There are other keys which combinational use
for various purposes. For example combination of ‘CTRL + S’ is used for saving
the typed information.
Fig.: DVORAK keyboard
There are X and Y sensing lines are available below to the
each labeled button. When we press any button or combination of button
according to that specific coded information is transferred to the CPU though the
wire.
Various multimedia keyboards are
also available in the market in some addition key set are mounted on the
keyboard
.
Advantages of keyboard:
1. Keyboard
is easy to use.
2. Various
buttons for different purposes.
3. Combination
of keys is perfect for the GUI selection.
4. Design
as per user requirement.
5. Buttons
are mounted on the keypad as per user finger movement and memory logic
6. Use in multipurpose
way
Disadvantages of Keyboard
1. Occupy size 2. Once button fail to press no use of keyboard.
(2) Mouse
Mouse is traditional and most
popular input devices which is also known as point and draw devices. When
student learn computer through paint mouse is useful device. Mouse is design
for the GUI interfacing. It is simple hand held device which is easily fitted
in the user hand. When we move the mouse on the entire monitor screen it
changes cursor according to the display. When it is on the editing text it look
like as (I)
while when we want to select any GUI button or any functionality it is look
like as (
) or (
). When we move mouse the arrow position is also moves and
changes its various locations. With the help of mechanism user of computer
easily pick up and selects the appropriate operation in the GUI screen.
Normally mouse has two buttons on the left and right side, in which left side
button is used for selection of the object while right side button is used for
selection of object properties. Scroller
is available in the middle position of this buttons which is used for
scrolling the pages in up or down side.
By the use of mouse it is used for drag and drop facility.
Mouse is classified into two types that are mechanical mouse and optical
mouse.
Fig. : Mouse types
Due to features of optical mouse over mechanical mouse it is
popular in market. Mechanical mouse is failed in the market due to several
reasons like rotating of mouse positions, dust cleaning problems etc. Optical
mouse spread laser light through LED. This light spread over the plane surface
and scans the area and reflects the lasers to internal microprocessor.
According to movement it displays on the monitor.
We change the buttons manufacturing features with the help of
controls as per user requirements.
Advantages of Mouse
1. Best
for the GUI selection 2. Easy for the use.
3. Easily
fitted in user palm of hand.
Disadvantages of Mouse
1. Not
useful in case of huge working since there are more controls are use in higher
degree.
2. Scrolling
causes finger related problems.
3. When
ball of mechanical mouse is surrounded with dust then it is problematic for
movement and it is clean again and again.
(3) Trackball
Trackball is
pointing device much similar to the mechanical mouse only difference is that
ball is placed at the top. By moving that roller we easily move the position of
the cursor. Following table shows the
difference between mouse and trackball.
This trackball is also available in various size and shapes.
It also have same functionality buttons at the top. The special use of the
trackball is for CAD / CAM drawing designs.
Advantages of Trackball
1. Easy
to use. 2. Occupies less space compare to mouse.
3. Best
for GUI selection.
Disadvantages of Trackball
1. Costly than mouse
(4) Joystick
The name joystick itself suggests it includes the magical
stick, which gives the same principle as the trackball. This trackball mostly
purchase for the playing the video games. It is applicable in various training
simulation. Also use in the industrial robotics applications.
The mechanism of joystick contains stick includes the button
at the top and ball at the below position. Ball basically fixed inside the
socket. This socket is recognizing the stick movement and work as per that,
while button is used for the object selection.
Fig.: Joystick
Various Multimedia joysticks are available in market for
playing the games in which various buttons are available for movement, shutting
or hitting button etc. the stick is comfortably set for the user palm.
Advantages of joystick
1. Easy for use 2. Futuristic in playing games.
Disadvantages of Joystick
1. Restricted for gaming
and simulations 2. Costly
(5) Touch Screen
Various information kiosks presents at Hotels, Airports,
railways stations, museums, malls, large banks, ATM’s this touch screen input device is available.
Advantages of Touch Screen Input
1. Best for input object
selection using finger
2. Input and output is
jointly acts as single unit and hence occupy less memory
Disadvantages of Touch Screen Input
1. costly display compare
to traditional computer set
(6) Light Pen
Electronic Light pen in point and draw device generally used
as select menu from display via pointing it. It is also use to draw graphics
designs. Movement of this electronic pen is changes the graphical movement.
This pen contain button for the selection.
Some of the light pen manufactured with special type of pad.
When we move pen on the pad as same as writing through ink pen on paper the
respective action we display on the screen.
Fig.: Light Pen
Advantages of Light Pen
1. Easy to use 2. Best for GUI selection
Disadvantages of Light Pen
1. Costly than other
input devices
2. Futuristic in playing games.
Data Gloves
