Friday, December 9, 2016

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.         
One other keyboard is also available for special purpose which is DVORAK keyboard, which all vowels and most common used consonant are mounted in the third row which specially designed for less figure movement.


                                                        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
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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

Touch screen is most advantageous input devices with is popular among the young generation. Today almost everyone uses the Touch screen mobile devices instead of button mobile which is application of touch screen input device. This is simplest and easiest input device among the all the input devices. All GUI selected simply through finger.                                                                                   Fig.: 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.


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