Raster-Scan Systems in Computer Graphics MCQ Questions and Answers

1. In a raster-scan display, the screen image is generated by
A) Drawing vectors directly
B) Scanning the screen line by line from top to bottom
C) Projecting polygons onto the screen
D) Refreshing only changed regions
Answer: B

2. The smallest addressable element of a raster display is a
A) Bit
B) Line
C) Pixel
D) Dot Matrix
Answer: C

3. The memory that stores intensity values for all pixels in a raster display is known as
A) Display Buffer
B) Video Memory
C) Frame Buffer
D) Screen Buffer
Answer: C

4. The refresh rate of a raster display is measured in
A) Frames per minute
B) Hertz (frames per second)
C) Pixels per line
D) Bits per second
Answer: B

5. In a raster system, the electron beam moves from left to right across the screen and then
A) Moves diagonally upward
B) Returns to bottom-left
C) Returns to the start of the next line
D) Stops until the next frame
Answer: C

6. The time taken for the beam to return from the end of one line to the beginning of the next is called
A) Vertical Retrace
B) Horizontal Retrace
C) Refresh Delay
D) Persistence
Answer: B

7. The time taken to move the beam from the bottom-right to top-left of the screen is called
A) Frame Delay
B) Vertical Retrace
C) Horizontal Blanking
D) Line Reset
Answer: B

8. The frame buffer memory required for a 640×480 display with 8-bit color is approximately
A) 150 KB
B) 200 KB
C) 307 KB
D) 512 KB
Answer: C

9. The horizontal scan frequency is given by
A) Number of pixels per frame
B) Number of lines per frame
C) Number of lines scanned per second
D) Refresh rate × resolution
Answer: C

10. The vertical scan frequency is the same as
A) Line scan rate
B) Pixel clock rate
C) Frame refresh rate
D) Bit rate
Answer: C

11. The component responsible for generating timing signals to control raster scanning is
A) CPU
B) Memory Controller
C) Video Controller
D) Display Processor
Answer: C

12. The term “raster” originally means
A) Vector drawing
B) Bit pattern
C) A rectangular grid of pixels
D) Frame sequence
Answer: C

13. The process of converting geometric primitives into pixel representation is called
A) Transformation
B) Scan Conversion
C) Rasterization
D) Clipping
Answer: B

14. In a raster system, the image is stored as a
A) Set of polygons
B) 2D matrix of pixel intensities
C) List of line segments
D) Tree of nodes
Answer: B

15. The refresh buffer of a raster display holds
A) Only color data
B) Coordinates of endpoints
C) Intensity or color values for each pixel
D) Vector paths
Answer: C

16. The frame buffer must be refreshed periodically because
A) It is volatile memory
B) Phosphor persistence is short
C) The CPU demands it
D) Resolution changes over time
Answer: B

17. For a resolution of 1024×768 and 24-bit color, how much memory is required for a single frame buffer?
A) 1 MB
B) 1.5 MB
C) 2.25 MB
D) 3 MB
Answer: C

18. The function of a digital-to-analog converter (DAC) in raster systems is to
A) Convert images to data
B) Convert stored pixel values into analog voltages for the display
C) Control beam deflection
D) Perform scan conversion
Answer: B

19. The electron beam intensity in a CRT raster system determines
A) The brightness of the pixel
B) The refresh rate
C) The pixel location
D) The beam deflection angle
Answer: A

20. The control unit that reads frame buffer data and refreshes the display is the
A) Display Processor
B) CPU
C) Video Controller
D) Pixel Clock
Answer: C

21. The term “rasterization” means
A) Clipping polygons
B) Converting vector data into raster format
C) Computing 3D transformations
D) Adjusting pixel intensity
Answer: B

22. The raster scan technique displays
A) Random line drawings
B) Filled areas and continuous tone images
C) Only outlines
D) Symbols only
Answer: B

23. The frame rate of a display system is the number of
A) Pixels displayed per second
B) Frames displayed per second
C) Horizontal lines drawn
D) Retraces per second
Answer: B

24. The beam movement across a raster display is controlled by
A) Current regulators
B) Deflection coils
C) Phosphor type
D) Video amplifier
Answer: B

25. A frame buffer with two memory planes is used for
A) Doubling resolution
B) Double buffering
C) Color correction
D) Reducing refresh time
Answer: B

26. Double buffering helps in
A) Increasing color depth
B) Improving resolution
C) Eliminating flicker and tearing
D) Saving memory
Answer: C

27. The advantage of raster scan over vector scan is
A) Higher drawing speed
B) Lower memory
C) Ability to represent shaded and realistic images
D) No need for refresh
Answer: C

28. The process of drawing pixels between two specified endpoints of a line is
A) Line clipping
B) Line rasterization
C) Vector plotting
D) Scan filling
Answer: B

29. The Bresenham’s algorithm is used for
A) Line rasterization
B) Polygon clipping
C) Color interpolation
D) Shading
Answer: A

30. The intensity resolution of a display refers to
A) Pixel density
B) Number of possible intensity levels per pixel
C) Frame rate
D) Screen refresh rate
Answer: B

31. The video controller synchronizes
A) CPU, memory, and display timing
B) Frame buffer and printer
C) Display refresh and sound output
D) Memory and network interface
Answer: A

32. Refresh rate × total number of pixels per frame equals
A) Frame buffer size
B) Pixel clock frequency
C) Bandwidth
D) Resolution
Answer: B

33. The pixel clock controls
A) The timing of pixel data transfer to the display
B) The brightness of pixels
C) CPU speed
D) Frame buffer writes
Answer: A

34. The phenomenon of flicker occurs when
A) Refresh rate is too high
B) Refresh rate is too low
C) Persistence is too long
D) Phosphor is too bright
Answer: B

35. Typical refresh rates for raster displays range from
A) 10–20 Hz
B) 20–40 Hz
C) 60–100 Hz
D) 200–400 Hz
Answer: C

36. The term “refresh buffer” is synonymous with
A) Z-buffer
B) Frame buffer
C) Color lookup table
D) Shadow map
Answer: B

37. In raster scan systems, the image definition is stored in
A) Memory (Frame Buffer)
B) Magnetic Disk
C) Phosphor Layer
D) Display Processor
Answer: A

38. The typical persistence of a CRT used in raster systems is about
A) 100 ms
B) 50 ms
C) 1–2 ms
D) 20 ms
Answer: C

39. The horizontal resolution of a display defines
A) The number of color levels
B) The number of distinct pixel columns
C) The refresh rate
D) The scan frequency
Answer: B

40. Vertical resolution defines
A) Pixel brightness
B) Refresh frequency
C) Number of pixel rows
D) Color depth
Answer: C

41. A 1280×1024 raster system has how many total pixels?
A) 1.2 million
B) 1.31 million
C) 1.5 million
D) 2 million
Answer: B

42. Increasing the resolution of a raster system requires
A) Lower refresh rate
B) Larger frame buffer memory
C) Smaller frame buffer memory
D) Higher persistence
Answer: B

43. The lookup table in a color raster display maps
A) Vector data to coordinates
B) Pixel codes to actual RGB intensities
C) Color depth to refresh rate
D) Frame rate to frequency
Answer: B

44. A color frame buffer with 8 bits per pixel can display how many colors simultaneously?
A) 128
B) 255
C) 256
D) 512
Answer: C

45. Raster-scan systems use which color generation method?
A) Subtractive
B) Additive (RGB)
C) Multiplicative
D) Gamma-based
Answer: B

46. The component that reads pixel data and controls beam intensity is the
A) Frame Buffer
B) Video Controller
C) CPU
D) LUT
Answer: B

47. In raster scan systems, the term “bitmap” represents
A) A 2D array of bits indicating pixel ON/OFF states
B) Line endpoints
C) Vector equations
D) Display processor commands
Answer: A

48. For monochrome displays, the frame buffer stores
A) RGB triplets
B) A single bit or byte per pixel
C) Hue values
D) Pixel coordinates
Answer: B

49. The raster system that supports intensity values greater than 1-bit uses
A) Vector frame buffer
B) Multi-plane frame buffer
C) Single-plane frame buffer
D) ROM display buffer
Answer: B

50. The synchronization between CPU updates and display refresh is handled by
A) Display Processor or Controller
B) GPU Shader
C) RAMDAC
D) I/O Bus
Answer: A

51. The refresh memory in a raster display is read
A) Randomly by CPU
B) Sequentially by video controller during display refresh
C) By user input
D) Through system clock
Answer: B

52. In a raster-scan CRT, each complete scanning cycle of the screen is called a
A) Sweep
B) Trace
C) Frame
D) Retrace
Answer: C

53. A system with 800×600 resolution and 16 bits per pixel needs how much memory for one frame?
A) 600 KB
B) 937.5 KB (≈ 0.92 MB)
C) 1.2 MB
D) 2 MB
Answer: B

54. The component converting pixel data to analog voltage is
A) ADC
B) DAC (Digital-to-Analog Converter)
C) Multiplexer
D) Amplifier
Answer: B

55. The vertical blanking interval is the time during which
A) Pixels are updated
B) Beam returns from bottom to top
C) Brightness increases
D) CPU transfers data
Answer: B

56. The horizontal blanking interval occurs
A) When beam moves from end of one line to start of next
B) Between frames
C) During display refresh
D) When color changes
Answer: A

57. The total time for scanning one frame =
A) 1 ⁄ horizontal frequency
B) 1 ⁄ vertical frequency
C) 1 ⁄ pixel clock
D) 1 ⁄ color depth
Answer: B

58. Which device handles the generation of synchronization signals in a raster-scan system?
A) CPU
B) Video Controller
C) Display Driver
D) Monitor
Answer: B

59. In raster-scan, image intensity is defined by
A) Pixel coordinates
B) Scan frequency
C) Frame buffer values
D) Beam width
Answer: C

60. The pixel frequency required for 1920×1080 display at 60 Hz refresh is approximately
A) 25 MHz
B) 60 MHz
C) 125 MHz
D) 200 MHz
Answer: C

61. The main difference between raster and vector displays is
A) Color depth
B) Drawing method (pixel grid vs line plotting)
C) Display size
D) Input device
Answer: B

62. Which of the following is NOT an advantage of raster systems?
A) Realistic image display
B) Low memory requirement
C) Support for filled areas
D) Rich color range
Answer: B

63. The term “refresh buffer” specifically refers to
A) Temporary CPU cache
B) Memory area repeatedly scanned to refresh image
C) Z-buffer memory
D) Frame sequencer
Answer: B

64. The electron beam in a raster display is blanked during
A) Horizontal and vertical retrace intervals
B) Frame display
C) Intensity modulation
D) Pixel activation
Answer: A

65. In an interlaced raster system, the screen is divided into
A) 4 fields
B) 2 fields (odd and even lines)
C) 8 segments
D) Multiple frames
Answer: B

66. The benefit of interlacing is
A) Reduced flicker without increasing bandwidth
B) Increased memory
C) Improved vector accuracy
D) Less color depth
Answer: A

67. The electron beam intensity is modulated according to
A) Pixel location
B) Frame buffer data
C) Beam speed
D) Color lookup table
Answer: B

68. In modern raster displays, the DAC output drives
A) Control grid
B) RGB signals to the monitor
C) CPU bus
D) Video memory
Answer: B

69. A system with 640×480 resolution, 60 Hz refresh needs how many pixels per second?
A) 10 million
B) 18.4 million
C) 25 million
D) 30 million
Answer: B

70. The number of intensity levels with n bits per pixel =
A) 2n–1
B) 2ⁿ
C) n²
D) 2n + 1
Answer: B

71. Anti-aliasing in raster graphics is used to
A) Smooth jagged edges of lines and curves
B) Increase refresh rate
C) Reduce color depth
D) Resize images
Answer: A

72. A bit-plane represents
A) One bit of all pixels across the display
B) A single row of pixels
C) A line segment
D) A color model
Answer: A

73. In 8-bit color systems, each pixel refers to a value in the
A) Frame buffer
B) Color lookup table (LUT)
C) Z-buffer
D) Display processor
Answer: B

74. A 24-bit true color raster display can represent how many colors?
A) 1 million
B) 8 million
C) 16.7 million
D) 32 million
Answer: C

75. The term “pixel aspect ratio” defines
A) Display brightness
B) Ratio of pixel width to height
C) Refresh rate
D) Gamma value
Answer: B

76. In double buffering, the displayed frame is from
A) Front buffer
B) Back buffer
C) Cache
D) DAC output
Answer: A

77. While one buffer is displayed, drawing is performed in
A) Front buffer
B) Back buffer
C) Overlay plane
D) Pixel cache
Answer: B

78. The rate at which the beam sweeps across one line is the
A) Vertical scan rate
B) Horizontal scan rate
C) Frame rate
D) Pixel clock
Answer: B

79. The bandwidth required for a raster display is proportional to
A) Color depth only
B) Resolution × refresh rate × color depth
C) Resolution only
D) Frame buffer size
Answer: B

80. Gamma correction is applied to
A) Adjust non-linear brightness response of displays
B) Increase resolution
C) Reduce flicker
D) Enhance contrast linearly
Answer: A

81. The Z-buffer is used to store
A) Color data
B) Depth values for visible surface determination
C) Pixel coordinates
D) Intensity values
Answer: B

82. The primary disadvantage of raster scan systems is
A) Realistic images
B) Large memory requirement
C) Fast rendering
D) Low color support
Answer: B

83. The display processor in a raster system mainly
A) Executes OS code
B) Handles refresh and pixel processing
C) Stores textures
D) Processes network data
Answer: B

84. Which part of the raster system ensures synchronization between CPU and display?
A) Clock generator
B) Video controller
C) Display driver
D) Phosphor coating
Answer: B

85. The refresh rate required to avoid visible flicker is at least
A) 30 Hz
B) 60 Hz
C) 20 Hz
D) 40 Hz
Answer: B

86. Increasing refresh rate beyond necessary values causes
A) Reduced power use
B) Higher power consumption without visible gain
C) Lower bandwidth
D) Color loss
Answer: B

87. The device responsible for storing display intensity data in raster systems is
A) CPU
B) Frame buffer memory
C) GPU registers
D) Display driver
Answer: B

88. A raster system with two frame buffers is useful for
A) Reducing resolution
B) Animation and smooth motion display
C) Decreasing color depth
D) Saving memory
Answer: B

89. The relation between horizontal frequency and vertical frequency is
A) Horizontal frequency = vertical frequency × number of lines per frame
B) Inverse proportional
C) Unrelated
D) Half the pixel rate
Answer: A

90. The term “scan line” refers to
A) A single horizontal row of pixels displayed in one pass
B) Vertical column of pixels
C) Entire frame
D) Diagonal trace
Answer: A

91. The number of scan lines per frame × frames per second =
A) Horizontal scanning frequency
B) Pixel clock
C) Vertical resolution
D) Color depth
Answer: A

92. The typical frame buffer memory type used in raster displays is
A) ROM
B) DRAM or VRAM
C) Cache SRAM
D) EPROM
Answer: B

93. The beam blanking signal is generated by
A) CPU
B) Video controller timing circuit
C) Frame buffer
D) Display processor
Answer: B

94. Which of the following improves temporal resolution of a display?
A) Higher color depth
B) Higher refresh rate
C) Lower bandwidth
D) Lower resolution
Answer: B

95. The raster display controller uses DMA mainly to
A) Access frame buffer without CPU intervention
B) Increase color depth
C) Reduce memory
D) Control intensity
Answer: A

96. The output of the frame buffer is fed to the
A) CPU
B) Digital-to-Analog Converter (DAC)
C) Hard disk
D) Z-buffer
Answer: B

97. The function of the display processor is to
A) Store only text data
B) Execute graphics commands and generate raster images
C) Drive the printer
D) Manage audio output
Answer: B

98. A monochrome raster system with 1024×1024 pixels requires how many bytes of storage if each pixel uses 1 bit?
A) 64 KB
B) 128 KB
C) 256 KB
D) 512 KB
Answer: B

99. The primary purpose of the refresh circuit is to
A) Convert digital to analog
B) Continuously read frame buffer to maintain image visibility
C) Change resolution
D) Increase memory
Answer: B

100. The complete raster display system comprises which major elements?
A) CPU and monitor only
B) Frame buffer, video controller, display device, and DAC
C) Keyboard, GPU, and cache
D) RAM and printer
Answer: B