---
title: "Define scan conversion"
subject: "Computer Graphics"
chapter: 2
key: "semester_5/computer_graphics:what-is-scan-conversion"
source: https://www.bctengineer.com/q/semester_5/computer_graphics/what-is-scan-conversion
site: BCT Engineering
---

# Define scan conversion

Computer Graphics · Chapter 2: Scan-Conversion

- Asked in: 2071 Shrawan, 2 marks
- Video: [What is Scan Conversion in Computer Graphics ? | Process of Scan Conversion | Computer Graphics](https://www.youtube.com/watch?v=CrXekdQM46s) — Simple Snippets
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/computer_graphics/what-is-scan-conversion
- Whole chapter: https://www.bctengineer.com/md/semester_5/computer_graphics/chapter-2

## Question

What is scan conversion?

## Short answer

Scan conversion (rasterization) is the process of converting geometric primitives like lines and circles into a set of pixels in the frame buffer. It determines which pixels best approximate the ideal shape on a raster display.

## Answer

**Scan conversion** (rasterization) is the process of converting a geometric primitive (line, circle, ellipse, polygon, text) specified by mathematical equations or end points into the set of pixels on the raster display that best represent it. It selects the pixel positions and sets their intensity in the frame buffer. Examples are the DDA and Bresenham's line algorithms.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Scan conversion is the process of:
   A. converting an analog image into digital form by a scanner
   B. converting a geometric primitive into the set of pixels that best represent it on a raster display
   C. filling a polygon with colour only
   D. converting 3D coordinates into 2D coordinates
   Answer: B. It selects pixel positions for primitives such as lines, circles and polygons. (Key point: Definition)

2. What does scan conversion do with the selected pixels?
   A. Sets their intensity in the frame buffer
   B. Stores them as vector commands in a display list
   C. Sends them directly to the keyboard
   D. Erases the background pixels
   Answer: A. Chosen pixels are written (with intensity) into the frame buffer for display. (Key point: Where the result goes)

3. Which of these are examples of scan-conversion algorithms?
   A. Cohen-Sutherland and Sutherland-Hodgman
   B. Translation and rotation
   C. DDA and Bresenham's line algorithms
   D. Window-to-viewport mapping
   Answer: C. DDA and Bresenham's turn a line into pixels; the others are clipping or geometric transformations. (Key point: Examples)

## Related in other subjects

- [CNF conversion (grammar with S→A|B)](https://www.bctengineer.com/question.md?key=semester_3%2Ftheory_of_computation%3Acnf-conversion-s-a-b) — Theory of Computation, chapter 3