Graphics Devices and Display Systems Questions and Answers

Q: Coordinates of a point (x, y) on a circle having centre at \((x_{c}, y_{c})\) and polar coordinates r and θ may be expressed in parametric polar form as :

The parametric form is \(x = x_{c} + r\cos\theta,\ y = y_{c} + r\sin\theta\).A point at distance r from the centre at angle \(\theta\) measured from the positive x-axis lies \(r\cos\theta\) to the right of the centre and \(r\sin\theta\) above it. Adding the centre's coordinates gives the point. As \(\theta\) runs from 0 to \(2\pi\), the point traces the whole circle.Swapping sin and cos, as in (B), traces the same circle starting from the top and going the other way, which is not the standard polar form. Options (C) and (D) give x and y the same function of \(\theta\), so they trace a straight diagonal segment, not a circle.

Q: Which of the following points lies over the line when Bresenham's line drawing algorithm is used to draw the line between the points (4, 6) and (15, 12) ?

The point on the line is (13, 11).From (4, 6) to (15, 12): \(\Delta x = 11\), \(\Delta y = 6\), so the slope is below 1 and x steps by 1. The decision parameter starts at \(p_0 = 2\Delta y - \Delta x = 1\). If \(p \ge 0\), y increases and \(p\) changes by \(2\Delta y - 2\Delta x = -10\); otherwise y stays and \(p\) changes by \(2\Delta y = 12\).x5678910111213y778899101011So the plotted points include (5, 7), (7, 8), (11, 10) and (13, 11). The options (5, 6), (7, 7) and (11, 9) each lie one pixel below the line.

Q: The beam penetration method for displaying color pictures are used in .................... .

The beam penetration method is used in Random scan monitors.A beam-penetration CRT coats the screen with two layers of phosphor, usually red and green. The speed of the electron beam decides how far it penetrates: slow electrons excite only the red layer, fast ones reach the green layer, and intermediate speeds give orange and yellow. It is an inexpensive way to get colour on random-scan (vector) displays, but offers only about four colours.Raster-scan colour monitors use the shadow-mask method, with three phosphor dots and three electron guns. Direct view storage tubes and generic refresh CRTs are not the setting for beam penetration.

Q: Identify odd one from the following :

The odd one is the Plotter.A plotter is an output device: it draws graphics and line drawings on paper with pens or other markers, under the computer's control.The other three are input devices. A digitizer (graphics tablet) converts positions on a drawing surface into coordinates, a touch panel senses where the screen is touched, and a trackball is a pointing device in which the user rolls a ball to move the cursor.

11.

Coordinates of a point (x, y) on a circle having centre at \((x_{c}, y_{c})\) and polar coordinates r and θ may be expressed in parametric polar form as :

A.\(x = x_{c} + r\cos\theta,\ y = y_{c} + r\sin\theta\)
B.\(x = x_{c} + r\sin\theta,\ y = y_{c} + r\cos\theta\)
C.\(x = x_{c} + r\cos\theta,\ y = y_{c} + r\cos\theta\)
D.\(x = x_{c} + r\sin\theta,\ y = y_{c} + r\sin\theta\)

Exam Year(s)

MH SET - 2019, SET Exam - 2019,

Answer: A

The parametric form is \(x = x_{c} + r\cos\theta,\ y = y_{c} + r\sin\theta\).

A point at distance r from the centre at angle \(\theta\) measured from the positive x-axis lies \(r\cos\theta\) to the right of the centre and \(r\sin\theta\) above it. Adding the centre's coordinates gives the point. As \(\theta\) runs from 0 to \(2\pi\), the point traces the whole circle.

Swapping sin and cos, as in (B), traces the same circle starting from the top and going the other way, which is not the standard polar form. Options (C) and (D) give x and y the same function of \(\theta\), so they trace a straight diagonal segment, not a circle.

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12.

Which of the following points lies over the line when Bresenham's line drawing algorithm is used to draw the line between the points (4, 6) and (15, 12) ?

A.(5, 6)
B.(7, 7)
C.(11, 9)
D.(13, 11)

Exam Year(s)

MH SET - 2020, SET Exam - 2020,

Answer: D

The point on the line is (13, 11).

From (4, 6) to (15, 12): \(\Delta x = 11\), \(\Delta y = 6\), so the slope is below 1 and x steps by 1. The decision parameter starts at \(p_0 = 2\Delta y - \Delta x = 1\). If \(p \ge 0\), y increases and \(p\) changes by \(2\Delta y - 2\Delta x = -10\); otherwise y stays and \(p\) changes by \(2\Delta y = 12\).

x	5	6	7	8	9	10	11	12	13
y	7	7	8	8	9	9	10	10	11

So the plotted points include (5, 7), (7, 8), (11, 10) and (13, 11). The options (5, 6), (7, 7) and (11, 9) each lie one pixel below the line.

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13.

The beam penetration method for displaying color pictures are used in .................... .

A.Refresh cathode ray tube monitors
B.Random scan monitors
C.Raster scan monitors
D.Direct view storage tube monitors

Exam Year(s)

MH SET - 2021, SET Exam - 2021,

Answer: B

The beam penetration method is used in Random scan monitors.

A beam-penetration CRT coats the screen with two layers of phosphor, usually red and green. The speed of the electron beam decides how far it penetrates: slow electrons excite only the red layer, fast ones reach the green layer, and intermediate speeds give orange and yellow. It is an inexpensive way to get colour on random-scan (vector) displays, but offers only about four colours.

Raster-scan colour monitors use the shadow-mask method, with three phosphor dots and three electron guns. Direct view storage tubes and generic refresh CRTs are not the setting for beam penetration.

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14.

Identify odd one from the following :

A.Digitizer
B.Touch panel
C.Plotter
D.Trackball

Exam Year(s)

MH SET - 2023, SET Exam - 2023,

Answer: C

The odd one is the Plotter.

A plotter is an output device: it draws graphics and line drawings on paper with pens or other markers, under the computer's control.

The other three are input devices. A digitizer (graphics tablet) converts positions on a drawing surface into coordinates, a touch panel senses where the screen is touched, and a trackball is a pointing device in which the user rolls a ball to move the cursor.

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15.

Which API is used to draw a circle ?

A.Circle ( )
B.Ellipse ( )
C.Round Rect ( )
D.Pie ( )

Exam Year(s)

UGC NET - 2012,

Answer: B

In the Windows GDI the circle is drawn with the Ellipse() function, by giving a bounding square whose width and height are equal. There is no function in the API called Circle(), so the first option is wrong.

RoundRect() draws a rectangle with rounded corners, and Pie() draws a wedge cut from an ellipse. The key gives Ellipse(), the function that draws a circle when its box is square.

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16.

If the pixels of an image are shuffled then the parameter that may change is

A.Histogram
B.Mean
C.Entropy
D.Covariance

Exam Year(s)

UGC NET - 2012,

Answer: D

Shuffling the pixels of an image does not change which grey levels occur or how often, so the histogram, the mean and the entropy, which depend only on those frequencies, stay the same. The covariance, which measures how neighbouring pixels are related to each other, depends on the positions of pixels, and a shuffle destroys that structure, so it may change. A shuffled picture looks like noise, which is why the spatial statistics change. The answer is Covariance, option (D).

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17.

The quantiser in an image-compression system is a

A.lossy element which exploits the psychovisual redundancy
B.lossless element which exploits the psychovisual redundancy
C.lossy element which exploits the statistical redundancy
D.lossless element which exploits the statistical redundancy

Exam Year(s)

UGC NET - 2012,

Answer: A

In an image compression system the quantiser reduces the number of grey levels or coefficient values, and it cannot be reversed, since the original values cannot be recovered from the rounded ones. So it is a lossy element, and it exploits psychovisual redundancy, the detail that the eye does not notice. The lossless elements are the coders that remove statistical redundancy, such as Huffman or arithmetic coding. The answer is option (A).

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18.

The transform which possesses the highest 'energy compaction' property is

A.Slant transform
B.Cosine transform
C.Fourier transform
D.Karhunen-Loeve transform

Exam Year(s)

UGC NET - 2012,

Answer: D

The Karhunen-Loeve transform, also called the Hotelling or principal component transform, has the best energy compaction of the transforms: it packs the largest share of the signal energy into the fewest coefficients, and it is the optimal transform in this sense, although it depends on the data. The cosine, Fourier and slant transforms are fixed transforms that come close but do not match it. The answer is Karhunen-Loeve transform, option (D).

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19.

The colour of an object is largely determined by its diffuse reflection coefficient. If \(K_{d}\) = (0.8, 0.4, 0), then what shall be the colour of the object, if the light used is blue and magenta ?

A.White and Red
B.Red and Blue
C.Black and White
D.Black and Red

Exam Year(s)

UGC NET - 2012,

Answer: D

The diffuse reflection coefficient (0.8, 0.4, 0) gives the fraction of red, green and blue light the object reflects, so it reflects no blue at all. Under blue light the object receives only blue, and reflects none of it, so it looks black. Magenta light is red plus blue; the object reflects 0.8 of the red and none of the blue, so it looks red. So the colours are black and red, option (D). Options with white or blue would need the object to reflect blue light.

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20.

Halftoning is defined as

A.a technique to obtain increased visual resolution using multiple intensity levels.
B.a technique for using minimum number of intensity levels to obtain increased visual resolution.
C.a technique to obtain increased visual resolution using maximum number of intensity levels.
D.a technique for using appropriate number intensity levels to obtain increased visual resolution.

Exam Year(s)

UGC NET - 2012,

Answer: B

Halftoning is a technique for using a minimum number of intensity levels, often only black and white, to give the impression of more levels, which increases the visual resolution: it trades spatial resolution for tonal resolution by using patterns of dots, as in newspaper pictures. The options that say it uses multiple, maximum or an appropriate number of levels give the opposite or an empty description. The answer is option (B).

Graphics Devices and Display Systems Questions and Answers

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