4.5.6.5 Vector graphics Quiz: AQA Computer Science, Unit 5

The 20 questions

1. How does a vector graphic represent an image?

   • As a grid of pixels with a colour for each
   • As a list of ASCII characters
   • As a set of sound samples
   • As a list of geometric objects and their properties

2. Which property is typically stored for a vector object?

   • Its coordinates, colour and line thickness
   • Its pixel depth and dpi, which determine how sharp the object appears when it is drawn
   • The file's compression ratio, which controls how much of the object is kept in memory
   • The number of samples per second used to draw the object at a given time

3. What is a vector graphic primitive?

   • An ADC conversion routine that turns a continuous voltage into a stream of binary values
   • A single pixel with a 24-bit colour value, stored as one entry in the bitmap grid
   • A basic shape such as a line, rectangle or circle
   • A compressed block of bitmap data, grouped so that many pixels can be stored together

4. What happens to a vector graphic when it is enlarged?

   • It loses its colour, since the enlarged shapes are drawn with a default grey fill
   • It needs more pixels to be stored, so the file grows each time the image is enlarged
   • It can be rescaled without losing quality, because its shapes are recalculated
   • It becomes blurry and pixelated, because the shapes are stretched across a fixed grid of pixels

5. Which type of graphic is best suited to logos and line drawings?

   • Sound files
   • Raw camera images
   • Vector graphics
   • Bitmapped graphics

6. What is a typical disadvantage of vector graphics?

   • They always need more storage than bitmaps, whatever the image being stored or drawn
   • They cannot store any colour, so every vector image must be printed in black and white
   • They cannot be scaled to a different size without first converting them into bitmaps
   • They are less suitable for detailed photographs with many colours and textures

7. Which list would describe a vector circle?

   • A sampled waveform
   • Centre coordinates and radius
   • The ASCII text 'circle'
   • A two-dimensional grid of pixel colours

8. A vector rectangle has corners (0,0), (10,0), (10,5) and (0,5). What is its area?

   • 30
   • 25
   • 15
   • 50

9. A vector circle has centre (2,2) and radius 4. Which stored description is correct?

   • A line from (2,2) to (4,4)
   • A rectangle with corners (2,2) and (4,4)
   • A circle that is 16 pixels wide
   • A circle with centre (2,2) and radius 4

10. A line runs from (0,0) to (3,4). What is its length?

    • 3.5 units
    • 12 units
    • 7 units
    • 5 units

11. A vector shape is a square with four sides each of length 5. What is its perimeter?

    • 10
    • 15
    • 20
    • 25

12. Which format stores a plain red square of 100 x 100 pixels more compactly?

    • Vector, since it stores a rectangle and a fill colour rather than 10,000 pixels
    • They are identical in size, since both formats store the same 100 x 100 area of the image
    • Bitmap, since it always stores less data than a vector for any simple shape at all sizes
    • Bitmap, since 10,000 pixels are smaller in total than the single rectangle a vector would hold

13. A polygon has 6 vertices. How many coordinate pairs must be stored at minimum?

    • 5
    • 12
    • 7
    • 6

14. A vector triangle has base 6 and height 4. What is its area?

    • 12
    • 24
    • 10
    • 6

15. A vector shape is scaled by 2 in both directions. What happens to its area?

    • It is multiplied by 8
    • It is unchanged, since only the coordinates change
    • It is multiplied by 2
    • It is multiplied by 4

16. Why can vector graphics be poorer than bitmaps for photographs?

    • Vector graphics cannot store any colour at all, so every drawing must be grey or black
    • Photographs always need less data as vectors, because the shapes replace the detail in the picture
    • Photographs contain millions of subtle colour variations that are costly to describe as shapes
    • Photographs must be black and white to be stored as shapes, because colour cannot be drawn

17. A logo is enlarged ten times, once as a bitmap and once as a vector. What is the result?

    • Both become identical bitmaps
    • The vector becomes blocky while the bitmap stays smooth
    • The bitmap becomes blocky, while the vector stays smooth
    • Both stay smooth because the file size is multiplied

18. Why does a vector file's size depend on the complexity of the image rather than its size in pixels?

    • Vector files store one object for each unit of area
    • Storage depends on the number and properties of the objects, not on the number of pixels
    • Vector size depends on colour depth only
    • Vector files store every pixel, so size depends on the image dimensions

19. Why might a designer use vector graphics for a map made of many lines?

    • Maps cannot be vectors, because lines are not shapes and must be stored as pixel grids
    • Vector maps always need a DAC to display them, because the lines are converted to voltages
    • Lines and shapes are stored compactly and remain sharp at any zoom level
    • Lines must be stored as photographs to print clearly, because vector lines do not print well

20. Which editing operation is easy with vector graphics but hard with bitmaps?

    • Moving or resizing an individual object without redrawing every pixel
    • Storing a colour for each pixel of the image, which is the basic job of a bitmap format
    • Displaying a photograph on a screen at its full resolution without any scaling applied
    • Counting the number of pixels in the image so that its total size can be reported

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