The document provides an overview of computer graphics, detailing its definition, applications, and basic terms such as images, objects, pixels, and resolutions. It discusses various coordinate systems used in 2D and 3D graphics, including Cartesian, polar, cylindrical, and spherical coordinates. Additionally, it covers file formats for graphics, their characteristics, and how they store digital images, highlighting the advantages and disadvantages of formats like TIFF, BMP, JPEG, GIF, PNG, and PCX.

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Computer Graphics
C o u r s e C o d e 3 1 3 0 0 1

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Teaching-Learning & Assessment Scheme
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Computer Graphics
Introduction
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Computer graphics involves technology to transforms and presents information in a visual form.
Computer graphics is the creation of pictures with the help of a computer.
Computer graphics has now become a common element in user interfaces, Example; T.V.
commercial motion pictures.
Computer graphics is an art of drawing pictures, lines, charts etc. using computers with the help
of programming.
Today, computer graphics is a core technology in digital photography, film, video games, cell
phone and computer displays and many specialized applications.

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Basic Terms of Computer Graphics:
• Image: an image is representation of a real world entity on a computer. It can be an actual picture
display. In simple terms image is defined by pixels.
• Object: Objects are real world entities (Person, Tree, Home) that can be customized using properties
like color, length and has behavior (animation scheme). In computer graphics we deal with both 2D and
3D descriptions of an object.
• Pixel (Picture element): a pixel is the smallest piece of information in an image. Pixels are normally
arranged in a regular 2D grid, and are often represented using dots or squares.
• Resolutions: Resolution is the number of rows that appear from top to bottom of a screen and in turn
the number of pixels or pixel elements that appear from left to right on each scan line. Based on this
resolution only the effect of picture appears on screen. greater the resolution greater will be the clarity of
picture. That is resolution value is directly proportional to clarity of picture.
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Applications of Computer Graphics:
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• Education and Training: Computer-generated model of the physical, financial and economic system is
often used as educational aids. Model of physical systems, physiological system, population trends or
equipment can help trainees to understand the operation of the system.
• Flight Simulator: It helps in giving training to the pilots of airplanes. These pilots spend much of their
training not in a real aircraft but on the ground at the controls of a Flight Simulator.
• Use in Biology: Molecular biologist can display a picture of molecules and gain insight into their structure
with the help of computer graphics.
• Computer-Generated Maps: Town planners and transportation engineers can use computer-generated
maps which display data useful to them in their planning work.
• Entertainment: Computer Graphics are now commonly used in making motion pictures, music videos and
television shows.
• Visualization: It is used for visualization of scientists, engineers, medical personnel, business analysts for
the study of a large amount of information.
• Architect: Architect can explore an alternative solution to design problems at an interactive graphics
terminal. In this way, they can test many more solutions that would not be possible without the computer.

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Unit.1 Basics of
Computer Graphics

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COURSE CONTENT
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Co-ordinate system
Coordinate system is a way of assigning numbers to points.
Coordinate systems are used to specify the position and orientation of objects in a virtual space.
A coordinate system is a system of numbers, symbols, and axes that is used to describe the position of
a point or object in space.
2D Co-ordinate System: In 2D, we need a pair of numbers to specify a point and the co-ordinates are
referred to as x and y.

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Co-ordinate system
3D Co-ordinate System: In 3D, we need three numbers to specify a point and along with the x and y
dimensions, we can determine the actors position based on the z axis this third co-ordinates is often called
z (inclusion of depth).
3D graphics applications use two types of Cartesian coordinate systems:
• Left-handed
• Right-handed
In both coordinate systems, the positive x-axis points to the right, and positive y-axis points up. The fingers
represents x and y directions. The direction of thumb points, either toward or away is the direction that the
positive z-axis points for that coordinate system.

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There are several different types of coordinate systems that are commonly used in computer graphics;
Cartesian coordinate systems(2D): The most commonly used coordinate system in computer graphics is the
Cartesian coordinate system. In this system, a point in space is defined by two or three numbers: its x-coordinate, y-
coordinate. The x-coordinate specifies the point's position along the x-axis, the y-coordinate specifies the point's
position along the y-axis. In 3D graphics a 3rd z-coordinate is used it incuse the depth of object.

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Polar coordinate systems(2D): The Polar coordinate system is another commonly used coordinate system in
computer graphics. In this system, a point in space is defined by two numbers: its radius and angle. The radius
specifies the distance of the point from the origin, and the angle specifies the direction of the point from the origin.
To convert from Cartesian to polar coordinates, you need to first determine the radius of the point. This can be done
using the Pythagorean theorem, which states that the square of the radius is equal to the sum of the squares of the x-
coordinate and the y-coordinate. In other words, the radius is the square root of the sum of the squares of the x
coordinate and the y-coordinate.

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Once the radius has been determined, the angle can be calculated using the arc tangent function. This function
takes the y-coordinate and the x-coordinate as inputs and returns the angle in radians. The angle can then be
converted to degrees if desired.
For example, to convert the point (3,4) from Cartesian to polar coordinates, first determine the radius using the
Pythagorean theorem:
radius = sqrt(3^2 + 4^2) = 5
Next, use the arc tangent function to determine the angle:
angle = atan2(4/3) = 53.13 degrees
Therefore, the polar coordinates of the point (3,4) are (5,53.13).

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3D Extension of Polar coordinate system:
Cylindrical coordinate systems(3D): Athree-dimensional coordinate system that is used to specify a point's location
by using the radial distance, the angle(θ), and the height of the point from a particular plane is known as a cylindrical
coordinate system.
Point Mapping from rectangular coordinate system to cylindrical coordinate system;

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Spherical coordinate systems(3D): the spherical co-ordinate system is representing geometric figures in three
dimensions using three co-ordinates: the radial distance of a point from a fixed origin, the zenith angle from the positive
z-axis and the azimuth angle from the positive x-axis.

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Point mapping in spherical coordinate system:

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• Graphics/Image file formats are standardized ways of organizing and storing digital images.
• This formats describes how data related to the image will be stored.
• Data can be stored in compressed, uncompressed and vector format.
• Each format of the image has a different advantages and disadvantages.
Graphics file formats
• TIFF (.tif, .tiff)
• BMP (.bmp)
• JPEG (.jpg, .jpeg)
• GIF (.gif)
• PNG (.png)
• PCX (.pcx)
Following are some graphics file formats;

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BMP (.bmp):
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• Tagged Image File Format.
• Store image data without losing any data.
• Do not perform any compression.
• Image have a high quality
• Size of image is large.
• Good for printing.
• Extremely flexible in terms of colors.
• Used in photo editing software (Photoshop)
TIFF (.tif, .tiff):
• Bitmap image file format
• Developed by Microsoft for windows
• It's typically uncompressed or uses lossless compression.
• Follows TIFF properties
• Generally recommended to use TIFF files.

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GIF (.gif):
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• Joint Photographic Expert Group.
• Jpeg files are images that have been compressed to store a lot of information in
small size file.
• Most digital cameras store photos in jpeg format.
• Jpeg is compressed in a way that loses some of the image detail during the
compression in order to make the file small and thus called “Lossy Compression”.
• Usually used for photographs on the web.
JPEG (.jpg, .jpeg):
• Graphic Interchange Format.
• This format compresses images but as different from the jpeg
• File can’t make as small as jpeg.
• No details are lost in the compression thus is “Lossless Compression”.
• GIF also have an extremely limited colour range
• Suitable for the web but not for printing.
• GIFs can also be used for animation.

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PCX (.pcx):
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• Portable Network Graphics Files.
• Lossless image format.
• Designed to replace gif formats.
• GIF supports 256 colours unlike PNG supports 16 million
colours.
PNG (.png):
• Personal Computer eXchange
• PCX is a raster graphics file format developed by ZSoft for
early PC graphics applications.
• Simple format, supports basic raster graphics.
• Limited color depth (256 colors),
• relatively outdated compared to modern formats,
• less efficient compression compared to newer formats.

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Graphics functions & standards:
Text mode,
Graphic mode,
Shapes,
Colors
Graphics standards.

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Thank You…