# Image Processing

• Last Updated : 15 Jun, 2018

 Question 1
A technique used to approximate halftones without reducing spatial resolution is known as _________.
 A Halftoning B Dithering C Error diffusion D None of the above
UGC NET CS 2014 Dec - III    Image Processing
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Question 1 Explanation:
Halftone is a graphic design technique in which image reproduced with the help og dots(various color). A technique used to approximate halftones without reducing spatial resolution is known as Dithering. Error diffusion is a type of halftoning in which neighboring pixel being disturbed(quantization residual is distributed ) that have not yet been processed. So, option (B) is correct.
 Question 2
Given a simple image of size 10 × 10 whose histogram models the symbol probabilities and is given by The first order estimate of image entropy is maximum when
 A a = 0, b = 0, c = 0, d = 1 B a = 1 / 2, b = 1 / 2, c = 0, d = 0 C a = 1 / 3, b = 1 / 3, c = 1 / 3, d = 0 D a = 1 / 4, b = 1 / 4, c = 1 / 4, d = 1 / 4
UGC NET CS 2014 Dec - III    Image Processing
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 Question 3
A Butterworth lowpass filter of order n, with a cutoff frequency at distance D 0 from the origin, has the transfer function H(u, v given by
 A 1 / (1 + [ D(u, v) / D0]2n) B 1 / (1 + [ D(u, v) / D0]n) C 1 / (1 + [D0 / D(u, v) ]2n) D 1 / (1 + [D0 / D(u, v) ]n)
UGC NET CS 2014 Dec - III    Image Processing
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 Question 4
A graphic display system has a frame buffer that is 640 pixels wide, 480 pixels high and 1 bit of color depth. If the access time for each pixel on the average is 200 nanoseconds, then the refresh rate of this frame buffer is approximately :
 A 16 frames per second B 19 frames per second C 21 frames per second D 23 frames per second
UGC NET CS 2018 July - II    Image Processing
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Question 4 Explanation:

Total pixels in the frame buffer = (width  x height)= 640 x 480 px = 307200

Here, color depth is 1 bit.

Memory required by frame buffer = Memory required for total pixel =

Total pixels in the frame buffer x (Color depth) = 307200 x 1

If access time for each pixel on the average is 200 ns

Time required to refresh  "frame buffer" = Memory required by frame buffer x 200 ns = 61440000 nano second = 61440000 x 10−9 second

Then, refresh rate of frame buffer =

number of frame changes per second = 1 / 61440000 x 10−9 second = 100,00,00,000 / 61440000 = 100,000 / 6144 = 16.2760 = 16 (Approximately)

There are 4 questions to complete.
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