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Chapter 6: Computer Graphics and Multimedia System: MCQ Practice for the NEC License Exam (AItE)

This chapter contributes 10 of the 100 questions in the IT Engineering license exam. Below are its subtopics, what is usually tested, and 12 free sample questions with answers and explanations.

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Subtopics in this chapter

What is usually tested

Graphics questions cover raster and random-scan displays, line and circle drawing algorithms, area filling, 2D and 3D transformations, window-to-viewport mapping, projections, clipping algorithms, Bezier and spline curves, visible-surface methods such as the Z-buffer, and illumination and shading models. Multimedia questions ask about media types, audio and MIDI, image and video formats, animation, and compression with JPEG and MPEG.

Sample questions with answers

Try each question before opening the answer. These 12 are taken from the 103 questions for this chapter in the practice bank.

1. In a raster-scan display system, the picture definition is stored as a set of intensity values in the: (6.1 Introduction of computer graphics)

  1. Frame buffer
  2. Display list
  3. Depth buffer
  4. Instruction register
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Answer: A. Frame buffer
A raster system keeps the intensity of every screen point in the frame (refresh) buffer and repaints the screen from it.

2. A random-scan (vector) display produces a picture by: (6.1 Introduction of computer graphics)

  1. Sweeping the electron beam across every scan line from top to bottom
  2. Directing the electron beam only along the lines that make up the picture
  3. Switching liquid-crystal cells on and off one row at a time
  4. Copying pixel intensities out of a frame buffer on every refresh
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Answer: B. Directing the electron beam only along the lines that make up the picture
A random-scan system draws one line at a time, in any order, from a list of line-drawing commands.

3. Which basic transformation repositions an object along a straight-line path without changing its size, shape or orientation? (6.2 Two and three-dimensional transformations)

  1. Translation
  2. Rotation
  3. Scaling
  4. Shear
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Answer: A. Translation
Translation adds the same displacement to every point, so the object moves rigidly.

4. A scaling transformation that uses the same scaling factor in every coordinate direction is called: (6.2 Two and three-dimensional transformations)

  1. Differential scaling
  2. Uniform scaling
  3. Shearing
  4. Reflection
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Answer: B. Uniform scaling
Equal scaling factors keep the object's proportions; unequal factors give differential scaling.

5. For a polygon lying in the plane Ax + By + Cz + D = 0, the surface normal is given by the vector: (6.3 3D Objects representation, and visible surface detections)

  1. (A, B, D)
  2. (B, C, D)
  3. (A, B, C)
  4. (A, C, D)
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Answer: C. (A, B, C)
The coefficients A, B and C of the plane equation are the components of a vector normal to the plane.

6. Blobby-object models are most suitable for representing: (6.3 3D Objects representation, and visible surface detections)

  1. Scenes that are stored only as edges
  2. Flat-faced objects such as boxes and buildings
  3. Objects made by rotating a profile about an axis
  4. Non-rigid shapes such as water droplets, muscles and melting objects
Show answer
Answer: D. Non-rigid shapes such as water droplets, muscles and melting objects
Blobby objects change shape and blend when they come close, so they are modelled with density functions rather than fixed surfaces.

7. In an illumination model, ambient light represents: (6.4 Illumination models and surface rendering)

  1. Light that passes through a transparent surface
  2. Light that travels directly from a point source to the surface
  3. The bright highlight seen on a shiny surface
  4. Uniform background light that results from many reflections in the scene
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Answer: D. Uniform background light that results from many reflections in the scene
Ambient light has no direction; it lights every surface equally and stands for the combined reflections from the surroundings.

8. For an ideal diffuse (Lambertian) surface, the reflected intensity depends on the angle between the surface normal and the: (6.4 Illumination models and surface rendering)

  1. Direction to the light source
  2. Direction to the viewer
  3. Specular-reflection direction
  4. Direction of the scan line
Show answer
Answer: A. Direction to the light source
Diffuse light is scattered equally in all directions, so it depends on the light direction but not on the viewing direction.

9. By the usual technical definition, a multimedia system must be able to process at least: (6.5 Introduction to multimedia)

  1. One continuous (time-dependent) and one discrete (time-independent) medium
  2. Two discrete media, such as text and graphics
  3. Two continuous media, such as audio and video
  4. Three different media at the same moment
Show answer
Answer: A. One continuous (time-dependent) and one discrete (time-independent) medium
A multimedia system is characterised by the integrated, computer-controlled handling of both continuous and discrete media.

10. Which of the following is a discrete (time-independent) medium? (6.5 Introduction to multimedia)

  1. An audio recording
  2. A still image
  3. A video clip
  4. An animation sequence
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Answer: B. A still image
Text and still images do not change with time; audio, video and animation are continuous media.

11. Which class of compression techniques is lossless and ignores the meaning (semantics) of the data being compressed? (6.6 Data compression, user interfaces and multimedia application)

  1. Source coding
  2. Entropy coding
  3. Hybrid coding
  4. Vector quantisation
Show answer
Answer: B. Entropy coding
Entropy coding treats the data as a plain sequence of symbols; source coding uses knowledge about the kind of signal.

12. Which of the following is an entropy-coding technique? (6.6 Data compression, user interfaces and multimedia application)

  1. Differential pulse code modulation
  2. Discrete cosine transform
  3. Huffman coding
  4. Sub-band coding
Show answer
Answer: C. Huffman coding
Huffman, run-length and arithmetic coding are entropy coders; DCT, DPCM and sub-band coding are source-coding techniques.

Practise this chapter

The full mock tests mix 10 questions from this chapter with 10 from each of the other nine, under the real 2-hour limit. Chapter practice mode lets you work through this chapter alone, untimed, with the explanation shown after every question.

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