This document provides definitions and explanations of various concepts in computer graphics: 1. It defines key terms like computer graphics, scalar, point, and line and explains their meanings in the context of digital images. 2. It describes processes like scan conversion and different types of displays like raster scan and random scan displays. 3. It also covers topics such as color models, plotters, frame buffers, BRDF functions, and image file formats.

1. a)
i. Computer graphics:
Computer graphics refers to the creation, manipulation, and display of visual content using
computers. It involves the use of software tools and hardware devices to create and render
images, animations, and videos.
ii. Scalar:
Scalar is a mathematical term that refers to a quantity that has only magnitude and no
direction. Scalars can be represented by a single numerical value, such as temperature,
mass, or speed.
iii. Point:
In computer graphics, a point refers to a position in space that is defined by a set of
coordinates. It is the smallest element of a digital image and is typically represented by a
single pixel.
iv. Line:
In computer graphics, a line is a geometric figure that is defined by two points. It is a series
of connected points that extend in a straight or curved direction. Lines can be used to create
shapes, such as triangles, circles, and polygons, and can be used to represent paths, edges,
and boundaries in a digital image.
b)
1. Keyboard
2. Mouse
3. Microphone
4. Joystick or gamepad
c)
In computer graphics, scan conversion is the process of transforming a geometric shape or image into a
digital representation that can be displayed on a computer screen. This process involves breaking down
the shape or image into discrete pixels and determining which pixels to activate to create the desired
image. The process is also known as rasterization or image sampling. The quality of the resulting image is
affected by factors such as the resolution of the display, the size of the pixels, and the complexity of the
shape or image being converted.
d)
a quadric surface is a three-dimensional geometric shape that is defined by a mathematical equation of
second degree, such as a sphere, cylinder, cone, or ellipsoid. Quadric surfaces are used to model 3D
objects in computer graphics and can be manipulated and rendered using specialized software tools.

2. 2
a) The CMY and HSV color models are two popular color models used in computer graphics and image
processing. The main differences between the two models are:
1. Color Representation: In the CMY color model, colors are represented by three primary colors -
cyan, magenta, and yellow. The color values range from 0 to 100%, with 0% representing no
color and 100% representing the full color intensity. In contrast, the HSV color model represents
colors using three parameters - hue, saturation, and value. Hue defines the color, saturation
determines the intensity of the color, and value represents the brightness of the color.
2. Color Space: The CMY color model operates in a subtractive color space, which means that the
colors are created by subtracting light from white. When all three primary colors are combined,
they create black. On the other hand, the HSV color model operates in an additive color space,
which means that the colors are created by adding light together. When all three parameters are
at maximum, they create white.
3. Color Mixing: In the CMY color model, colors are mixed by subtracting the complementary color.
For example, when cyan and magenta are combined, they create blue. When cyan, magenta, and
yellow are combined, they create black. In contrast, in the HSV color model, colors are mixed by
adjusting the hue, saturation, and value parameters to create a new color.
4. Applications: The CMY color model is commonly used in printing and color reproduction, while
the HSV color model is commonly used in computer graphics and image processing, particularly
for color selection and manipulation.
b) Electrostatic plotters are a type of printer used in computer graphics that use electrostatic charges to
transfer toner onto paper or other surfaces. The advantages of electrostatic plotters in computer
graphics include:
1. High Resolution: Electrostatic plotters can produce high-quality, high-resolution prints with
sharp, precise lines and curves. This makes them ideal for printing technical drawings,
schematics, and other detailed graphics.
2. Speed: Electrostatic plotters are faster than other types of plotters and can produce prints
quickly, which is important for printing large or complex images.
3. Versatility: Electrostatic plotters can print on a variety of media, including paper, transparency
film, and other types of materials, which makes them ideal for a range of applications.
4. Low Maintenance: Electrostatic plotters are relatively easy to maintain and require less
maintenance than other types of plotters. They also have fewer moving parts, which reduces the
risk of mechanical failure.

3. 5. Cost-Effective: Electrostatic plotters are more cost-effective than other types of plotters, such as
inkjet or laser plotters, especially when printing large or complex images. This makes them a
popular choice for businesses and organizations that need to produce technical drawings or
other graphics on a regular basis.
c) Random scan displays and raster scan displays are two types of computers displays used to create and
display images. The main differences between the two are:
1. Scanning Method: Raster scan displays use a scanning pattern to draw an image one line at a
time from the top to the bottom of the screen, while random scan displays use a point-to-point
drawing method to draw an image.
2. Refresh Rate: Raster scan displays have a fixed refresh rate, which means that the entire screen
is redrawn at a constant rate, typically 60 times per second. In contrast, random scan displays
have a variable refresh rate, which means that the rate at which the image is drawn depends on
the complexity of the image.
3. Resolution: Raster scan displays have a fixed resolution that is determined by the number of
pixels on the screen. In contrast, random scan displays can have varying resolutions, depending
on the capability of the display hardware.
4. Complexity: Raster scan displays are typically simpler than random scan displays and are often
used for displaying text and simple graphics. Random scan displays are more complex and can be
used for displaying more complex images and animations.
5. Cost: Raster scan displays are generally less expensive than random scan displays because they
are simpler and require less advanced hardware.
d) Bi-directional Reflection Distribution Function (BRDF) is a function that describes the way in which
light is reflected by a surface in different directions. The BRDF is defined as the ratio of the amount of
light reflected in a particular direction to the amount of light that falls on the surface from that direction.
The classes and properties of BRDF can be discussed as follows:
1. Symmetry: The BRDF must be symmetric, i.e., it should remain the same when the directions of
the incident and reflected light are swapped. This property is also known as reciprocity. It
ensures that the amount of light that is reflected in a particular direction is the same as the
amount of light that would be received from that direction.
2. Energy Conservation: The BRDF must satisfy the energy conservation law, which states that the
total amount of light that is reflected by a surface cannot be greater than the total amount of
light that falls on it. This property ensures that the total amount of energy in the system is
conserved.

4. 3. Positivity: The BRDF must be positive, i.e., it cannot have negative values. This property ensures
that the amount of light reflected by a surface is always greater than or equal to zero.
4. Isotropy/Anisotropy: The BRDF can be either isotropic or anisotropic. An isotropic BRDF has the
same reflective properties in all directions, while an anisotropic BRDF has different reflective
properties in different directions.
5. Microfacet Models: BRDFs can be classified based on the underlying microfacet models used to
describe the surface. These models include the Lambertian model, which assumes that the
surface reflects light equally in all directions, and the Cook-Torrance model, which models the
surface as a collection of microfacets with varying orientations and roughness.
e)
A frame buffer is a region of memory in a computer that stores the image data for display on a computer
monitor or other output device. It is a data structure that holds the color and intensity values of
individual pixels, representing the image that is to be displayed on the screen.
Factors to consider when choosing a frame buffer include:
1. Resolution: The resolution of the frame buffer determines the number of pixels that can be
displayed on the screen. A higher resolution frame buffer can display more pixels, resulting in a
higher quality image.
2. Color Depth: The color depth of the frame buffer determines the number of colors that can be
displayed on the screen. A higher color depth frame buffer can display more colors, resulting in a
more vibrant and accurate image.
3. Refresh Rate: The refresh rate of the frame buffer determines how often the image is updated
on the screen. A higher refresh rate frame buffer can display smoother motion and reduce the
perception of flicker.
4. Memory Bandwidth: The memory bandwidth of the frame buffer determines how quickly data
can be read from or written to the frame buffer. A higher memory bandwidth frame buffer can
handle more complex graphics and reduce latency.
5. Compatibility: The frame buffer must be compatible with the display hardware and software
being used. Compatibility issues can lead to display problems and reduced performance.

5. f)
1. JPEG (Joint Photographic Experts Group): JPEG is a lossy compression algorithm that is widely
used for compressing photographic images. It works by analyzing the image data and removing
redundant information, such as high-frequency spatial data and color information that is
imperceptible to the human eye. The degree of compression can be adjusted to balance image
quality and file size.
2. PNG (Portable Network Graphics): PNG is a lossless compression algorithm that is widely used
for compressing images with transparent backgrounds, such as logos and graphics. It works by
encoding the image data using a predictive algorithm that takes advantage of the similarities
between adjacent pixels. Unlike JPEG, PNG does not remove any image data, so the compressed
image is an exact replica of the original. However, this results in larger file sizes than JPEG.