Introduction and Overview of Graphics System

 Introduction and Overview of Graphics System

In the digital age, computer graphics play a crucial role in our lives. From the breathtaking visuals in your favorite video games to the animations in movies, graphics systems are responsible for creating these captivating experiences. In this blog, we will embark on a journey to explore the fascinating world of computer graphics.

Definition and Representative Uses of Computer Graphics

Computer graphics can be defined as the field of study that focuses on creating, manipulating, and rendering visual content using computers. Its applications are diverse and far-reaching. Consider these representative uses:

1. Entertainment and Media: Computer graphics are widely used in the entertainment industry, including video games, animated movies, and television shows.
2. Design and Visualization: Graphic design, architectural visualization, and product design benefit from computer graphics to create realistic 2D and 3D models.
3. Education and Training: Educational software often employs computer graphics to make learning more interactive and engaging.
4. Medical Imaging: Computer graphics assist in medical imaging, allowing for detailed visualization of the human body for diagnosis and surgery planning.
5. Engineering and Simulations: Engineers use computer graphics for simulations and modelling of complex systems and structures.
6. Virtual Reality (VR) and Augmented Reality (AR): These technologies heavily rely on computer graphics to provide immersive experiences in various fields, including gaming, training, and education.
7. Data Visualization: Visualizing complex data sets through charts, graphs, and interactive visual displays makes data analysis more accessible.
8. Advertising and Marketing: Computer graphics are used to create eye-catching advertisements, logos, and marketing materials.
9. Film and Video Production: From special effects to post-production editing, computer graphics enhance the film and video production process.
10. Gaming Industry: Video games, both on PC and consoles, rely on computer graphics to create stunning visuals and immersive gameplay experiences.
11. Interior Design: Interior designers use computer graphics to create digital representations of room layouts and designs.
12. Art and Animation: Digital artists and animators use computer graphics tools to create artwork and animations for various purposes.
13. Cartography and Geographic Information Systems (GIS): Creating maps and spatial data analysis rely on computer graphics for visualization.
14. Fashion Design: Fashion designers utilize computer graphics for designing clothing and textiles.
15. Web and User Interface (UI) Design: Designing websites and user interfaces is heavily reliant on creating visually appealing and user-friendly graphics.

These are just a few examples of the diverse applications of computer graphics across various industries.

Overview of Coordinate System

The foundation of computer graphics lies in the coordinate system. This system provides a framework for defining the positions of objects in a graphical environment. It consists of X, Y, and sometimes Z axes, allowing precise positioning and rendering of objects.

2D vs. 3D: Coordinate systems can be 2D (plane) or 3D (space), depending on the application.

Polar Coordinates: An alternative to Cartesian, using radial distance and angles (r, θ) to locate points.

Spherical Coordinates: A 3D system using radial distance, polar angle (θ), and azimuthal angle (ϕ).

Cylindrical Coordinates: A 3D system using radial distance, angle (θ), and height (z).

Coordinate Origin: A point of reference (0,0) from which measurements are made.

Positive and Negative Directions: Coordinates can extend positively and negatively along each axis.

Orthogonality: Axes are typically orthogonal, meaning they meet at right angles.

Unit Vectors: Directional vectors (i, j, k) represent positive movement along the axes.

Transformations: Coordinate systems can be transformed, rotated, or translated.

World and Local Coordinates: Many applications use a world coordinate system and local systems for objects.

Homogeneous Coordinates: Used in computer graphics and transformation matrices for 3D transformations.

Curvilinear Coordinates: Special systems for specific applications, like polar coordinates in physics.

Definition of Scan Conversion

Scan conversion is a fundamental concept in graphics. It refers to the process of converting geometric shapes and objects into a grid of pixels. This grid can then be displayed on a screen, forming the basis of digital images.

Rasterization and Rendering

Rasterization and rendering are at the heart of creating images. Rasterization converts vectors and shapes into pixel data, while rendering involves shading, lighting, and creating a final image from these pixels.

Raster Scan & Random Scan Displays

Displays are the windows to the graphical world. Raster scan and random scan displays are two primary types:

• Raster Scan: These displays use a scanning pattern to render images, commonly found in CRT monitors.
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Architecture of Raster Graphics System with Display Processor

Understanding the architecture of a raster graphics system is crucial. It includes components like the CPU, GPU, and display processor, all working together to deliver a seamless visual experience.

The video controller employs two registers to store the coordinates of the screen pixels. Initially, x = 0 and y = ymax (the maximum y-coordinate). The video controller retrieves the pixel value stored in the frame buffer corresponding to this pixel position. Then, it increments the x value by 1 and retrieves the corresponding y value. This process continues, retrieving pixel values line by line. Once the last pixel is reached, the registers are reset to their initial values, and the process repeats.

 Display Processor

The display processor, also known as the graphics controller, plays a vital role in offloading graphics-related tasks from the CPU. In addition to the system memory, a separate display processor memory area can be provided.

One of the primary tasks of the display processor is scan conversion, which involves digitizing a picture definition from an application program into a set of pixel-intensity values stored in the frame buffer. Geometric objects, such as lines, are converted into sets of discrete intensity points. Characters can be defined using rectangular grids or curved outlines.

To optimize memory usage, scan lines are often stored as sets of integer pairs. Each pair consists of an intensity value and the number of adjacent pixels on the scan line that have the same intensity. This compression technique is known as run-length encoding.

By employing the display processor, the CPU is freed from handling graphics-related operations, allowing it to focus on other tasks.

The architecture of Random Scan Systems

Random scan systems differ significantly from raster graphics. They utilize calligraphic technology, enabling precise drawing and less flickering. n random-scan systems, an application program is inputted and stored in the system memory alongside a graphics package. Graphics commands within the program are translated by the graphics package into a display file, which is then stored in the system memory. The display processor accesses this display file to refresh the screen. During each refresh cycle, the display processor cycles through each command in the display file program.

The display processor in a random-scan system is sometimes referred to as a display processing unit or a graphics controller.

To draw graphic patterns on a random-scan system, the electron beam is directed along the component lines of the picture. Lines are defined by specifying the coordinates of their endpoints. These input coordinate values are then converted into x and y deflection voltages. The scene is drawn one line at a time, with the beam positioned to fill in the line between the specified endpoints.

1. 1.                    1.    Basic Principle:
1. Raster Scan: Sequential scanning of the entire screen row by row from top to bottom.
2. Random Scan: Directly addressing and illuminating specific points on the screen, allowing selective drawing.
2. Drawing Technique:
1. Raster Scan: Utilizes a CRT beam that moves horizontally and vertically to draw complete images.
2. Random Scan: Employs a set of CRT beams, each controlled independently to target individual points.
3. Speed:
1. Raster Scan: Slower due to scanning every pixel systematically.
2. Random Scan: Faster for selective drawing since it targets only necessary points.
4. Applications:
1. Raster Scan: Common in traditional computer monitors.
2. Random Scan: Used in specialized applications like vector displays and high-end graphics.
5. Storage:
1. Raster Scan: Requires more memory for storing pixel information.
2. Random Scan: More memory-efficient as it doesn't store every pixel.
6. Editing and Manipulation:
1. Raster Scan: Easily supports image editing and manipulation.
2. Random Scan: Not suitable for extensive image modifications.
7. Scalability:
1. Raster Scan: Suited for pixel-based displays of various resolutions.
2. Random Scan: Limited by the number of points on the screen.
8. Vector Graphics:
1. Raster Scan: Not ideal for vector graphics and geometric shapes.
2. Random Scan: Excellent for precise rendering of vector graphics.
9. Complexity:
1. Raster Scan: Simple in terms of hardware and control.
2. Random Scan: More complex due to multiple independently controlled beams.
10. Line Drawing:
1. Raster Scan: Uses algorithms for line drawing.
2. Random Scan: Capable of drawing lines directly without algorithms.
11. Examples:
1. Raster Scan: Typical in modern LCD and LED displays.
2. Random Scan: Historical example includes early oscilloscopes.
12. Cost:
1. Raster Scan: Cost-effective and widely adopted.

Random Scan: Expensive and limited to specialized use cases.

In this blog, we've embarked on a journey through the world of computer graphics, exploring key concepts, definitions, and applications. As you continue to study this fascinating field, you'll gain a deeper appreciation for the role of graphics in our digitally-driven world.