📘 Introduction to Computer Graphics — Exam Notes

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🔹 1. Definition

Computer Graphics is a branch of computer science that deals with the creation, manipulation, and representation of visual images and objects using computers.

👉 In simple terms: It is the process of generating images (pictures, animations, diagrams) with the help of a computer.

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🔹 2. Key Concepts

✔️ 2.1 Types of Computer Graphics

1. Raster Graphics (Bitmap)

   • Made up of tiny dots called pixels
   • Example: Digital photos
   • Resolution-dependent (quality decreases when zoomed)

2. Vector Graphics

   • Made using mathematical equations (lines, curves, shapes)
   • Example: Logos, illustrations
   • Resolution-independent (can be scaled without losing quality)

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✔️ 2.2 Basic Components of Computer Graphics System

1. Input Devices

   • Keyboard, Mouse, Scanner, Light Pen

2. Output Devices

   • Monitor, Printer, Plotter

3. Graphics Software

   • Tools used to create/edit images (e.g., drawing software)

4. Frame Buffer

   • Memory area that stores pixel information for display

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✔️ 2.3 Pixel (Picture Element)

• Smallest unit of an image

• Each pixel has:

  • Position (x, y)
  • Color value

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✔️ 2.4 Resolution

• Number of pixels on screen (e.g., 1920 × 1080)
• Higher resolution → clearer image

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✔️ 2.5 Aspect Ratio

• Ratio of width to height of a screen Example: 16:9

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🔹 3. Applications of Computer Graphics

1. Computer-Aided Design (CAD)

   • Used in engineering and architecture

2. Entertainment

   • Movies, animation, video games

3. Education & Training

   • Simulations, virtual labs

4. Medical Imaging

   • X-rays, CT scans

5. Graphical User Interfaces (GUI)

   • Windows, icons, menus

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🔹 4. Graphics Pipeline (Basic Steps)

Step-by-Step Process:

1. Modeling

   • Creating objects (shapes, structures)

2. Transformation

   • Moving, rotating, scaling objects

3. Viewing

   • Deciding camera position and angle

4. Projection

   • Converting 3D objects into 2D view

5. Rendering

   • Adding colors, lighting, textures

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🔹 5. Types of Graphics Systems

1. Interactive Graphics

   • User can interact in real-time (e.g., games)

2. Non-Interactive Graphics

   • Predefined images (e.g., printed pictures)

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🔹 6. Important Terms

• Rendering: Process of generating final image
• Clipping: Removing parts of objects outside display area
• Transformation: Changing position/size/orientation of objects
• Viewport: Area on screen where image is displayed
• Window: Portion of world coordinates selected for display

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🔹 7. Basic Transformations (Important)

✔️ Translation (Moving object)

Formula: [ x' = x + t_x,\quad y' = y + t_y ]

✔️ Scaling (Resizing object)

[ x' = x \cdot s_x,\quad y' = y \cdot s_y ]

✔️ Rotation (Rotating object)

[ x' = x \cos\theta - y \sin\theta ] [ y' = x \sin\theta + y \cos\theta ]

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🔹 8. Coordinate Systems

1. World Coordinates

   • Real-world positions

2. Screen Coordinates

   • Pixel-based positions on screen

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🔹 9. Diagram Descriptions (for exams)

👉 Graphics Pipeline Diagram

• Show flow:

  Object → Transformation → Projection → Rendering → Display
  

👉 Pixel Grid Diagram

• Draw small boxes arranged in rows and columns
• Label one box as “Pixel”

👉 Coordinate System

• X-axis (horizontal), Y-axis (vertical)
• Origin (0,0)

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🔹 10. Advantages of Computer Graphics

• Improves visualization
• Saves time and cost
• Enhances communication
• Enables simulations

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🔹 11. Limitations

• Requires high processing power
• Expensive hardware/software
• Complex algorithms

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📝 Likely Exam Questions

1. Define computer graphics and explain its applications.
2. Differentiate between raster and vector graphics.
3. What is a pixel? Explain resolution and aspect ratio.
4. Describe the components of a computer graphics system.
5. Explain the graphics pipeline with steps.
6. What are basic transformations? Explain with formulas.
7. Define rendering and clipping.
8. Explain coordinate systems in computer graphics.
9. Write short notes on CAD and GUI.
10. Compare interactive and non-interactive graphics.

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⚡ Quick Revision Summary

• Computer Graphics = Creating images using computers
• Two types: Raster (pixels) & Vector (mathematical shapes)
• Pixel = smallest unit of image
• Resolution = clarity of image
• Pipeline = Modeling → Transformation → Projection → Rendering
• Key transformations: Translation, Scaling, Rotation
• Widely used in CAD, games, medical, GUI
• Important concepts: Rendering, Clipping, Viewport

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