Input devices in computer graphics

INPUT DEVICES
 Input devices are things we use to put information

into a computer.

 An input device is any hardware device that sends

data to the computer, without any input devices, a
computer would only be a display device and not allow
users to interact with it, much like a TV.

 For example, a keyboard is an input device.
 Input devices other than the keyboard are sometimes

called alternate input devices.

 Mice, trackballs, and light pens are all alternate input

devices.

Graphic
Tablet

Keyboard

Data
Glove

Mouse
Light Pen

Graphic
Cards

Keyboard
 Invented 100 years agoUsed to type data into the computer
 Most common input device today
 Has special keys for giving the computer commands
 Commands tell the computer to do something, like save the file
 These special keys are called command or function keys

 There is no specific standard but we have stuck to the qwerty keyboard
 Different types of keyboards
 It depends what we need to input
 ATM keyboard, piano keyboard, alarm system keboard etc

Types of Keyboard
 There are following types of Keyboards:
1. ERGONOMIC KEYBOARD
 The artifact of this keyboard is slightly broader and different in
shape, when compared with the normal keyboard.
 In this key board certain space will be existing between the two
sets of keys and the countered shape of this key board allow the
users to place their hands in the natural position to type.
 These key boards are mostly used by the people who often work
with the key board as their usage is easier and is less stressful for
the wrist. The following figure: Ergonomic keyboard shows how
the set of keys are separated with gaps in between.

Types of Keyboard(Cont’d)
2.


Wireless Keyboard

A wireless keyboard, the name itself doles the meaning that this
keyboard can be operated without addressing a wired connection to
the processor.
 The wireless keyboards are also referred as Cordless keyboards; these
keyboards require batteries to provide the electricity which usually
delivered through a PS/2 or USB cable. “AA” or “AAA” batteries are
most widely used standard batteries for wireless keyboards.
 Apple Macs are known to revolutionize the wireless keyboard by
making them thinner than the wired ones. These keyboards usually
work at 2.4 GHz frequency and come with a dongle that connects and
makes them communicate with the computer.

Advantages of Keyboard
 You may chat with other players if in an online game such as

World of Warcraft, Runescape, Toontown, and the like.
Relatedly, some games require a keyboard to play. You may
enter information into databases (Such as WikiPedia,
WikiAnswers)
Homework, schoolwork, or work-work can be done neatly
using keyboard-required software. (Microsoft word, notepad)
The use of a keyboard can enable shortcuts with some programs.
Any information that needs to be entered into a computer,
network, and/or etc. can be added with, usually, ease.

Disadvantages of Keyboard
Keyboards can add up in price. Wireless keyboards can get up

to, but are not limited to, $125.
If not wireless, keyboards can add another wire (or more) to a
bulk of other wires, making any workspace messy(confused).
If wireless, there may be very slight interference on some rare
frequency channels. Multiple wireless keyboards may cross paths
if settings are not set up correctly. (Resulting in as tunned,
confused user)

Mouse
A pointing device that fits comfortably under the palm of

your hand
The most widely used pointing device on desktop
computers
The mouse controls the movement of the pointer, also
called the mouse pointer, on the screen

How does a mechanical mouse
work?
mouse
wheel
mouse
wheel
 A rubber or metal ball is

buttons
buttons

on its underside
When the ball rolls in a certain
direction, electronic circuits in
the mouse translate the movement
of the mouse into signals the
computer understands
A mouse pad provides better
traction and protects the ball
from a build up of dust and dirt

button
button

ball
ball

How does an optical mouse
work?
Uses devices that emit & sense light

to detect the mouse’s movement
Some use optical sensors; others
use laser
More precise than a mechanical
mouse & does not require cleaning
Slightly more expensive

back
back
button
button

wheel
wheel
button
button

forward
forward
button
button

optical
optical
sensor
sensor

Advantages of Mouse
 Can be installed without any installation software.
 Mouse scroll is actually interchangeable.

a. Free scrolling pertaining to web browsing
b. Just click scrolling for choosing weapons and even potions

Disadvantages of Mouse
 They need a flat surface to be used, or else they won't function.

Light Pens
A light pen is a pen-shaped input device.
A light pen utilizes a light sensitive detector, requiring you to hold a

pen and point it at the screen.
The device contains a light sensor which, when pointed at a cathode
ray tube screen, generates a signal each time the electron beam raster
passes by the spot the pen is pointing at.
Light enters the lens of a light pen, where it encounters a
photoelectric cell, which converts the energy to a signal that is sent to
the computer. The light is obtained from the refresh of the CRT, and
at the instant the light is generated, the computer knows what location
on the screen is being refreshed; this information is coordinated with
the signal from the light pen, and is subsequently used by the graphics
software to make a decision.

Advantages of Light Pens
 Allows you to select objects on a display screen - It has great

accuracy-drawing directly on the screen so it is more accuratemore precise
 Durability and Accuracy : The light pen and computer respond
instantly when you move it or click on one of the buttons located
on the pen's sides. The tip cannot damage the computer screen
in any way.
Flexibility: In addition to having the full range of mouse options,
including allowing you to drag and drop, you can use the light
pen to directly draw or write on the screen. This makes
providing your signature relatively simple.

Advantages of Light Pens
The amount of work space is reduced when you use a light pen

instead of a mouse because you do not need a flat surface to
operate a light pen.
Maintenance and Value :Buying a light pen to use on your CRT
computer monitor is cheaper than buying a touch-screen
monitor. The same is true for repairs or replacements.

Disadvantages of Light Pens
Light pens have the advantage of 'drawing' directly onto the

screen, but this can become uncomfortable, and they are not as
accurate as digitizing tablets.
Light pens normally require a specially designed monitor to
work with.

Graphic cards
A graphics card, also known as a video card, is a piece of

hardware installed in a computer that is responsible for
rendering the image on the computer’s monitor or display
screen.
Graphics cards come in many varieties with varying features
The first consideration when buying a graphics card is to be sure
it is capable of displaying the best resolution the monitor can
support. For Liquid Crystal Display (LCD) monitors this means
supporting the native resolution. Cathode Ray Tube (CRT)
monitors do not have a native resolution. In this case, ensure
the card is capable of supporting the highest resolution, even if
the CRT monitor will be frequently used at lower resolutions.

Graphic cards
The second consideration is on-board memory. A

graphics card must work very hard to render images to the
screen. Unlike text files, graphics images are much larger files
consisting of great amounts of data that must be processed by the
graphics or video card. A faster card has its own resident
memory chips to perform this function so as not to impinge upon
the system’s Random Access Memory (RAM). Less robust cards
have less resident memory and require sharing system RAM to
process images.

Working of Graphic Cards
The images you see on your monitor are made of tiny dots called

pixels. At most common resolution settings, a screen displays over a
million pixels, and the computer has to decide what to do with every
one in order to create an image. To do this, it needs a translator -something to take binary data from the CPU and turn it into a picture
you can see. Unless a computer has graphics capability built into the
motherboard, that translation takes place on the graphics card.
A graphics card's job is complex, but its principles and components
are easy to understand. In this article, we will look at the basic parts of
a video card and what they do. We'll also examine the factors that
work together to make a fast, efficient graphics card.

Think of a computer as a company with its own art department.

When people in the company want a piece of artwork, they send
a request to the art department. The art department decides how
to create the image and then puts it on paper. The end result is
that someone's idea becomes an actual, viewable picture.
A graphics card works along the same principles. The CPU,
working in conjunction with software applications, sends
information about the image to the graphics card. The graphics
card decides how to use the pixels on the screen to create the
image. It then sends that information to the monitor through a
cable.

Creating an image out of binary data is a demanding process. To

make a 3-D image, the graphics card first creates a wire frame out of
straight lines. Then, it rasterizes the image (fills in the remaining
pixels). It also adds lighting, texture and color. For fast-paced games,
the computer has to go through this process about sixty times per
second. Without a graphics card to perform the necessary
calculations, the workload would be too much for the computer to
handle.
The graphics card accomplishes this task using four main components:
 A motherboard connection for data and power
 A processor to decide what to do with each pixel on the screen
 Memory to hold information about each pixel and to temporarily store

completed pictures
 A monitor connection so you can see the final result

Types of Graphic Cards
 There are main 4 types of Graphic Cards

1. Integrated
If you have a computer, but did not assemble it yourself or upgrade it in
any way, chances are that it uses an integrated graphics card to display
images on your screen. When a graphics card is described as integrated, it
refers to the card's relationship with the computer's motherboard.
Integrated graphics cards are sometimes also known as on-board graphics
cards. Integrated graphics cards are the default option that come with
standard motherboards. An integrated graphics card can be upgraded, but
it requires plugging a new graphics card into your computer's
motherboard and ignoring your old card.
Integrated graphics cards are the least powerful variety overall, at least
compared to the time period they are from. If you have an integrated
graphics card and want to play the latest video games, you will need to
upgrade.

2. PCI
 PCI graphics cards are graphics cards that use the PCI slots on your motherboard to
connect to your computer. PCI graphics cards are usually a little bit out of date, if
not extremely so. However, many older motherboards have PCI slots, but lack
newer varieties of connections. For this reason, there is still a reason to buy a PCI
graphics card — but only if you are trying to upgrade an older system.
3. AGP
 AGP graphics cards are named for the same thing PCI cards are — the slot they
connect to on a motherboard. AGP cards can have 4 speeds, the fastest being 8x.
However, if your motherboard only supports a lower speed, such as 1x, 2x, or 4x,
your graphics card will behave as if it is of that slower speed, rather than its real
speed. AGP connections are not quite as fast as PCI-E slots due to technological
limits, and as a result will not be developed to run at higher speeds. However, like
PCI cards, they are more widely compatible than the most cutting-edge cards.

4. PCI-Express
PCI-E cards are the most advanced, connecting to the
motherboard's PCI-E slot. PCI-E graphics cards can be
accelerated to 16x. In addition, a motherboard with more than
one PCI-E slot can have more than one PCI-E graphics card
connected to it, combining their power. However, this is a rare
scenario. This can also cause compatibility problems if not
planned out correctly; certain motherboards work better with
certain other specific brands of PCI-E video card.

Advantages of Graphic Cards
The advantage of a graphics card is that it allows you to hook up

a monitor and see what your computer is doing.
More room to run applications in, less scrolling side to side and
up and down in your windows, more colors (this isn't necessarily
true, but it is a closely related topic, and I'll address this issue
below), more colors means nicer looking pictures (ever notice
that annoying color banding (called dithering) in most of the
pictures you look at), A much less cluttered appearance (unless
you're one of those people who upon getting more space, feels
the need to fill it up).

Disadvantages of Graphic Card
The disadvantage is that your computer wont work without one.
With higher resolutions and colors, there is a performance hit

(speed), which could be big or small depending on your
hardware and the resolution you set up (generally it's a very
small performance hit). This is due to the fact that there
is much more information to deal with as well as more pixels to
update on-screen (I'll get to this below), The higher you set your
resolution, the smaller your icons and text, and your refresh rate
drops (I'll get to this too).

Data Glove
 Data Glove is a device to interact with animated artificial objects. Consider a

glove fitted with sensors and electrical wires hooked to a glove compatible
computer.
Here, we can see our hand inside the glove in the display monitor of the
computer. As we rotate or move our hand and manipulate our fingers, we
can see our hand inside the glove in the display monitor of the computer.
Consider further that a graphic object is described in the monitor. The object
may be animated. It may even be a scaled replica of a real life object.
Now , if we try to move our hand in space in such a way that the image of
our hand in the display manipulates the graphic object in the screen, we shall
have a strange feelings. With out actually touching anything, we may distort
the shape of the object using the image of our hand inside the dataglove! This
glove act as an agent to transport the user to an artificial domain.

A graphics tablet is a computer input device that enables a user to hand-draw
images and graphics, similar to the way a person draws images with a pencil and
paper.
These tablets may also be used to capture data or handwritten signatures.
It can also be used to trace an image from a piece of paper which is taped or
otherwise secured to the surface.
Capturing data in this way, either by drawing or entering the angles of linear polylines or shapes is called digitizing.
The device consists of a flat surface upon which
the user may "draw" or touch an image using an
attached stylus, a pen-like drawing device.
The image generally does not appear on the
tablet itself but, rather, is displayed on the
computer monitor.

 Easy way to control a computer
Easy way to draw a scale image on a computer
better quality of image
More effective than mouse input.
Can input pressure data for use in a graphics package

Touch screens break easily
The stylus pens can be easily lost therefore the graphics tablet

will not work
slower then paper drawing Can be awkward to access menus and
make selections Larger designs (A4 for example) are expensive
More expensive than a mouse, especially in the larger sizes.
Not as precise as a mouse for menu control, so it tends to be an
addition rather than a replacement
Graphic tablets are rather like electronic tracing paper and, like paper
,they one in all sizes from a modest A4 size to a very large A0 size
which will occupy the best part of a desk.

Input devices in computer graphics

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