Data compression mcq
Data compression
Unit 1
 Data compression
means to the file size.
Correct option is B
 Data compression and
encryption both work on binary
 False
 True Answer
Correct option is B
 What is compression?
 To compress something
by pressing it very hardly
 To minimize the time
taken for a file to be downloaded
 To reduce the size of
data to save space
 To convert one file
to another Answer
Correct option is C
 Data compression
usually works by .
 Deleting random bits
data
 Finding repeating
patterns Answer
Correct option is B
 Why data compressed?
 To optimise the data
 To reduce secondary
storage space
 To reduce packet
congestion on networks
 Both (B) and
(C)
Correct option is D
 Which is a type of
data compression?
 Resolution
 Zipping
 Inputting
 Caching
Correct option is B
 Data compression
involves
 Compression only
 Reconstruction only
 Both compression and
reconstruction
 None of the
above
Correct option is C
 Based on the
requirements of reconstruction, data compression schemes can be divided
into broad classes
 3
 2
 5
Correct option is C
 compression is the
method which eliminates the data which is not noticeable
and compression does
not eliminate the data which is not
 Lossless, lossy
 Lossy, lossless
 None of these
Correct option is B
 compression is
generally used for applications that cannot tolerate any difference
between the original and reconstructed data.
 Lossy
 Lossless
 Both
 None of these
Correct option is B
 What is compression
ratio?
 The ratio of the
number of bits required to represent the data before compression to the
number of bits required to represent the data after
 The ratio of the
number of bits required to represent the data after compression to the
number of bits required to represent the data before
 The ratio of the
number of bits required to represent the data after reconstruction to the
number of bits required to represent the data before
 The ratio of the
number of bits required to represent the data before reconstruction to the
number of bits required to represent the data after
Correct option is A
 Suppose storing an
image made up of a square array of 256×256 pixels requires 65,536 bytes.
The image is compressed and the compressed version requires 16,384 bytes.
Then the compression ratio is
.
 1:4
 4:1
 1:2
 2:1
Correct option is B
 Lossy techniques are
generally used for the compression of data that originate as analog
signals, such as
 Speech
 Video
 Both
 None of these
Correct option is C
 If fidelity or
quality of a reconstruction is , then the difference between the
reconstruction and the original is .
 High, small
 Small, small
 High, high
 None of the above
Answer
Correct option is D
 The development of
data compression algorithms for a variety of data can be divided
into
 2
 3
 4
 5
Correct option is A
 Which of the
following is true of lossy and lossless compression techniques?
 Lossless compression
is only used in situations where lossy compression techniques can’t be
used
 Lossy compression is
best suited for situations where some loss of detail is tolerable,
especially if it will not be detectable by a human
 Both lossy and
lossless compression techniques will result in some information being lost
from the original file
 Neither lossy nor
lossless compression can actually reduce the number of bits needed to represent
a file
Correct option is B
 Which of the
following would not be suitable for Lossy Compression?
 Speech
 Video
 Text
 Image
Correct option is C
 Which of the
following are not in a compressed format?
 MP3
 Bitmap
 MPEG
 JPEG
Correct option is B
 Information theory
was given by
 Claude von Regan
 Claude Elwood Shannon
 Claude Monet
 Claude Debussy
Correct option is B
 The unit of
information depends on the base of the log. If we use log base 2, the unit
is ; if we use log base e, the unit is ; and if we use log base
10, the unit
is .
 Hartleys, nats, bits
 Hartleys, bits, nats
 Bits, nats, hartleys
 Bits, hartleys, nats
Correct option is C
 According to Claude
Elwood Shannon’s second theorem, it is not feasible to transmit
information over the channel with error probability, although by
using any coding technique?
 Large
 May be large or small
 Unpredictable
 Small
Correct option is D
 The essential
condition/s for a good error control coding technique?
 Better error
correcting capability
 Maximum transfer of
information in bits/sec
 Faster coding &
decoding methods
 All of the
above
Correct option is D
 The prefix code is
also called as
 Block code
 Convolutional code
 Parity code
 Instantaneous
code
Correct option is D
 Self information
should be .
 Negative
 Positive
 Both
 None of these
Correct option is B
 A code in which no
codeword is a prefix to another codeword is called as
 Prefix cod
 Parity code
 Convolutional code
 Block code
Correct option is A
 The set of binary
sequences is called a , and the individual members of the set are
called .
 Codewords, code
 Code, codewords
 None of these Answer
Correct option is B
 Full form of ASCII is
 American Standard
Code for Information Intercaste
 American Standard
Codewords for Information Interchange
 American Standard
Code for Information Interchange
 American System Code
for Information Interchange
Correct option is C
 Composite source
models is a combination or composition of several sources. In which how
many source being active at any given time?
 All
 Only one
 Only first three
 None of these
Correct option is B
 For models used in
lossless compression, we use a specific type of Markov process called a
 Continous time Markov
chain
 Discrete time Markov
chain
 Constant time Markov
chain
 None of the
above
Correct option is B
 Markov model is often
used when developing coding algorithms for
 Speech
 Image
 Both
 None of these
Correct option is C
 Which of the
following compression type is supported by SQL Server 2014?
A. Row
B. Column
C. Both row and column
D. None of the mentioned
Correct option is C
 Point out the correct
statement:
 The details of data
compression are subject to change without notice in service packs or
subsequent releases
 Compression is not
available for system tables
 If you specify a list
of partitions or a partition that is out of range, an error will be
generated
 All of the mentioned
Correct option
is D
 In which type of Data
Compression, the integrity of the data is preserved?
A. Lossy Compression
B. Lossless Compression
C. Both of the above
D. None of the above
Correct option
is B
 Which of the
following are Lossless methods?
A. Runlength
B. Huffman
C. Lempel Ziv
D. All of the above
Correct option is D
 Which of the
following are lossy methods?
A. JPEG
B. MPEG
C. MP3
D. All of the above
Correct option is D
 In how many parts we
can divide audio and video services into broad categories?
A. Two
B. Three
C. Four
D. None of the above
Correct option is B
 Sequence of code
assigned is called
A. code word
B. word
C. byte
D. nibble
Correct option is A
UnitII
 Huffman codes
are codes and are optimum for a given model (set of probabilities).
 Parity
 Prefix
 Convolutional code
 Block code
Correct option is B
 The Huffman procedure
is based on observations regarding optimum prefix codes, which is/are

In an optimum code, symbols that occur more frequently (have a higher
probability of occurrence) will have shorter codewords than symbols that
occur less
 In an optimum
code,thetwo symbolsthat occurleast frequently will havethe samelength
 Both (A) and (B)
 None of these
Correct option is C
 The best algorithms
for solving Huffman codes
 Brute force algorithm
 Divide and conquer
algorithm
 Greedy algorithm
 Exhaustive
search
Correct option is C
 How many printable
characters does the ASCII character set consists of?
 128
 100
 98
 90
Correct option is B
 The difference
between the entropy and the average length of the Huffman code is called
 Rate
 Redundancy
 Power
 None of these
Correct option is B
 Unit of redundancy is
 bits/second
 symbol/bits
 bits/symbol
 none of these
Correct option is C
 The redundancy is
zero when
 The probabilities are
positive powers of two
 The probabilities are
negative powers of two
 Both
 None of the
above
Correct option is B
 Which bit is reserved
as a parity bit in an ASCII set?
 Sixth
 Seventh
 Eighth
 Ninth
Correct option is C
 Bits are needed for
standard encoding if the size of the character set is X
 X+1
 log(X)
 X^{2}
 2X
Correct option is B
10. In Huffman coding, data in a
tree always occur in
 Leaves
 Roots
 Left sub trees
 None of these
Correct option is A
11. An optimal code
will always be present in a full tree?
 True
 False
Correct option is A
 Running time of the
Huffman encoding algorithm is
 O(Nlog(C))
 O(Clog(C))
 O(C)
 O(log(C)) Answer
Correct option is B
 Running time of the
Huffman algorithm, if its implementation of the priority queue is done
using linked lists
 O(log(C))
 O(Clog(C))
 O(C^{2})
 O(C)
Correct option is C
 The unary code for a
positive integer n is simply n
followed by a .
 zero, ones
 ones, zero
 None of these
Correct option is B
 The unary code for 4
is .
 11100
 11110
 00001
 00011
Correct option is B
 In the Tunstall code,
all codewords are of However, each codeword represents a
number of letters.
 different, equal
 equal, different
 none of these
Correct option is B
 Tunstall coding is a
form of entropy coding used for
 Lossless data
compression
 Lossy data
compression
 Both
 None of these
Correct option is A
 The main advantage of
a Tunstall code is that
 Errors in codewords
do not propagate
 Errors in codewords
propagate
 The disparity between
frequencies
 None of these
Correct option is A
 Applications of
Huffman Coding
 Text compression
 Audio compression
 Lossless image
compression
 All of the above
Correct option is D
 An alphabet consist
of the letters A, B, C and D. The probability of occurrence is P(A) = 0.4,
P(B)= 0.1, P(C) = 0.2 and P(D) = 0.3. The Huffman code is
 A = 0 B = 111 C = 110
D = 10
 A = 0 B = 11 C = 10 D
= 111
 A = 0 B = 111 C = 11
D = 101
 A = 01 B = 111 C =
110 D = 10
Correct option is A
 The basic idea behind
Huffman coding is to
A. compress data by using fewer bits to encode fewer
frequently occuring characters
B. compress data by using fewer bits to encode more
frequently occuring characters
C. compress data by using more bits to encode more
frequently occuring characters
D. expand data by using fewer bits to encode more frequently
occuring characters
Correct option is B
 Huffman coding is an
encoding algorithm used for
A. lossless data compression
B. broadband systems
C. files greater than 1 Mbit
D. lossy data compression
Correct option is A
 A Huffman encoder
takes a set of characters with fixed length and produces a set of
characters of
A. random length
B. fixed length
C. variable length
D. constant length
Correct option is C
A Huffman code: A = 1, B = 000, C
= 001, D = 01 , P(A) = 0.4, P(B) = 0.1, P(C) = 0.2, P(D) = 0.3 The average
number of bits per letter is
 0 bit
 1 bit
 0 bit
 9 bit
Correct option is C
 Which of the
following is not a part of the channel coding?
A. rectangular code
B. Checksum checking
C. Hamming code
D. Huffman code
Correct option is D
 Which of the
following is the first phase of JPEG?
A. DCT Transformation
B. Quantization
C. Data Compression
D. None of the above
Correct option is D
 Which type of method
is used is used to compress data made up of combination of symbols?
A. Run length encoding
B. Huffman encoding
C. Lempel Ziv encoding
D. JPEG encoding
Correct option is A
 How many passes does
lossy compression makes frequently?
A. One pass
B. Two pass
C. Three pass
D. Four pass
Correct option is B
 Information is the
A. data
B. meaningful data
C. raw data
D. Both A and B
Correct option is B
UnitIII
 In dictionary
techniques for data compaction, which approach of building dictionary is
used for the prior knowledge of probability of the frequently occurring
patterns?
 Adaptive dictionary
 Static dictionary
 Both
 None of the
above
Correct option is B
 If the probability of
encountering a pattern from the dictionary is p, then the average number
of bits per pattern R is given by
 R=2112p
 R=9p
 R=21p
 R=12p
Correct option is A
 Static dictionary –
 permanent
 sometimes allowing
the addition of strings but no deletions
 allowing for
additions and deletions of strings as new input symbols are being read
 Both (A) and (B)
 Both (A) and (C)
Correct option is D
 Adaptive dictionary –
 holding strings
previously found in the input stream
 sometimes allowing
the addition of strings but no deletions
 allowing for additions
and deletions of strings as new input symbols are being read
 Both (A) and (B)
 Both (A) and
(C)
Correct option is E
 LZ77 and LZ78 are the
two algorithms published in papers by Abraham Lempel and Jacob Ziv in
1977 and 1978
 Lossy data
compression
 Lossless data
compression
 Both
 None of the above
Correct option is B
 Deflate =………….
 LZ78 + Huffman
 LZ77 + Huffman
 LZW + Huffman
 None of these
Correct option is B
 Full form of GIF
 Graphics Interchange
Form
 Graphics Inter Format
 Graphics Interchange
Format
 Graphics Interact
Format
Correct option is C
 LZ78
has compression but very decompression than
 fast, slow
 slow, fast
 None of these
Correct option is B
 Compression packages
which use an LZ77based algorithm followed by a variablelength coder.
 PKZip
 Zip
 PNG
 All of the above
Correct option is D
 Application of LZW
 GIF
 Zip
 PNG
 All of the above
Correct option is A
 Algorithm used for
solving temporal probabilistic reasoning
 Depthfirst search
 Hidden markov model
 Hidden markov model
 Breadthfirst
search
Correct option is C
 Where does the Hidden
Markov Model is used?
 Understanding of real
world
 Speech recognition
 Both
 None of the above
Correct option is B
 A coding scheme that
takes advantage of long runs of identical symbols is called as
 Movetofront coding
 Binary coding
 Huffman coding
 Movetoback coding
Correct option is A
 The idea with
wavelets is to represent a complicated function by
A. simple basic functions
B. sinus functions
C. lines
D. square functions
Correct option is A
 In a typical picture,
most pixels will be
A. equal
B. very different to their neighbors
C. bright
D. very similar to their neighbors
Correct option is C
 Without losing
quality, JPEG2000 can achieve compression ratios of
 2:1
 200:1
 2000:1
 20:1
Correct option is B
 The best visual
compression quality is achieved using
A. Fourier transform
B. Wavelets
C. DCT
D. Dolby
Correct option is B
 Which is the image
processing technique used to improve the quality of image for human
viewing?
A. compression
B. enhancement
C. restoration
D. analysis
Correct option is B
 To remove archival
compression and restore the data to column store compression
A. Use ALTER TABLE
B. Use ALTER COLUMN
C. Use ALTER DATABASE
D. All of the mentioned
Correct option is A
 Point out the wrong
A. You can enable or disable ROW or PAGE compression in
online state only
B. When you are compressing indexes, leaflevel pages can be
compressed with both row and page compression
C. Non–leaflevel pages do not receive page compression
D. None of the mentioned
Correct option is A
 What is image?
A. Picture
B. Matrix of pixel
C. Collection of pixel
D. All of these
Correct option is D
 An image transmitted
using wireless network:
A. corrupted as a result of lighting or other atmospheric
B. noncorrupted as a result of lighting or other
atmospheric
C. corrupted as a result of pixel
D. none of above
Correct option is A
UnitIV
 Which of the
following characterizes a quantizer
 Quantization results
in a nonreversible loss of information
 A quantizer always
produces uncorrelated output samples
 The output of a
quantizer has the same entropy rate as the input
 None of the
above
Correct option is A
 What is the
signaltonoise ratio (SNR)?
 The ratio of the
average squared value of the source output and the squared error of the
source output
 The ratio of the
average squared value of the source output and the mean squared error of
the source output
 The ratio of the
average squared value of the source output and the absolute difference
measure of the source output
 None of the
above
Correct option is B
 The output signal of
a scalar quantizer has property
 The output is a
discrete signal with a finite symbol alphabet
 The output is a
discrete signal with a countable symbol alphabet (but not necessarily a
finite symbol alphabet)
 The output signal may
be discrete or continuous
 None of the
above
Correct option is B
 What is a Lloyd
quantizer?
 For a given source,
the Lloyd quantizer is the best possible scalar quantizer in
ratedistortion That means, there does not exist any other scalar quantizer
that yields a smaller distortion at the same rate.
 The output of a Lloyd
quantizer is a discrete signal with a uniform pmf
 Both (A) and (B)
 A Lloyd quantizer is
the scalar quantizer that yields the minimum distortion for a given source
and a given number of quantization
Correct option is D
 Which of the
following statement is correct for comparing scalar quantization and vector
quantization?
 Vector quantization
improves the performance only for sources with memory. For iid sources,
the best scalar quantizer has the same efficiency as the best vector
quantizer
 Vector quantization
does not improve the ratedistortion performance relative to scalar
quantization, but it has a lower complexity
 By vector
quantization we can always improve the ratedistortion performance
relative to the best scalar quantizer
 All of the
above
Correct option is C
 If {x}_{n} is the source
output and {y}_{n} is the
reconstructed sequence, then the squared error measure is given by
 d(x, y) = (y – x)^{2}
 d(x, y) = (x – y)^{2}
 d(x, y) = (y + x)^{2}
 d(x, y) = (x – y)^{4}
Correct option is B
 If {x}_{n} is the source
output and {y}_{n} is the
reconstructed sequence, then the absolute difference measure is given by
 d(x, y) = y – x
 d(x, y) = x – y
 d(x, y) = y + x
 d(x, y) = x – y^{2}
Correct option is B
 The process of
representing a possibly infinite
set of values with a much
set is called quantization
 Large, smaller
 Smaller, large
 None of these
Correct option is A
 The set of inputs and
outputs of a quantizer can be
 Only scalars
 Only vectors
 Scalars or vectors
 None of these
Correct option is C
 Which of the folowing
is/are correct for uniform quantizer
 The simplest type of
quantizer is the uniform quantizer
 All intervals are the
same size in the uniform quantizer, except possibly for the two outer
intervals
 The decision
boundaries are spaced evenly
 All of the
above
Correct option is D
 If a Zero is assigned
a decision level, then what is the type of quantizer?
 A midtread quantizer
 A midrise quantizer
 A midtreat quantizer
 None of the
above
Correct option is B
 If a Zero is assigned
a quantization level, then what is the type of quantizer?
 A midtread quantizer
 A midrise quantizer
 A midtreat quantizer
 None of the above
Correct option is A
 The main approaches
to adapting the quantizer parameters:
 An offline or
forward adaptive approach
 An online or
backward adaptive approach
 Both
 None of the
above
Correct option is C
 Uniform quantizer is
also called as
 Low rise quantizer
 High rise quantizer
 Mid rise quantizer
 None of the
above
Correct option is C
 Non uniform quantizer
 Decrease
 Increase
 Doesn’t change
 None of the
above
Correct option is A
 The spectral density
of white noise is .
 Poisson
 Exponential
 Uniform
 Gaussian
Correct option is C
 Which audio/video
refers to ondemand requests for compressed audio/video files?
A. Streaming live
B. Streaming stored
C. Interactive
D. None of the above
Correct option is B
 According to Nyquist
theorem, how many times the highest frequency we need to sample an analog
signal?
A. Three
B. Two
C. Four
D. None of the above
Correct option is B
 Which encoding is
based on the science of psychoacoustics, which is the study of how people
perceive sound?
 Predictive
 Perceptual
 Both of the above
 None of the above
Correct option is B
 SDH uses to measure
block errors.
A. CRC
B. Rectangular code
C. bitinterleaved parity (BIP )
D. Simple parity check
 The minimum sampling
rate is called?
A. Data rate
B. symbol rate
C. Nyquist rate
D. None of the above
Correct option is C
 Spread spectrum is
used for
A. Encrypting signal
B. Hiding signal
C. Encrypting & Hiding signal
D. None of the mentioned
Correct option is C
 Which is a
quantization process?
A. Rounding
B. Truncation
C. Rounding & Truncation
D. None of the mentioned
Correct option is C
 . Quantization is
a……………..process.
A. Non linear
B. Reversible
C. Non linear & Reversible
D. None of the mentioned
Correct option is C
 The mutual
information between a pair of events is
A. Positive
B. Negative
C. Zero
D. All of the mentioned
Correct option is D
 The SNR value can be
increased by the number of levels.
 Increasing
 Decreasing
 Does not depend on
 None of the
mentioned
Correct option is A
 1 bit quantizer is a
A. Hard limiter
B. Two level comparator
C. Hard limiter & Two level comparator
D. None of the mentioned
Correct option is C
 The low pass filter
at the output end of delta modulator depends on
A. Step size
B. Quantization noise
C. Bandwidth
D. None of the mentioned
Correct option is C
 Quantization Matrix
in JPEG compression was introduced because
A. It is computationally more efficient to work with matrix
than with scalar quantization;
B. It allows better entropy encoding due to DC and AC
coefficient distribution in the 8×8 block matrix;
C. It allows better differentiation of DC and AC
coefficients in the 8×8 block matrix than a scalar quantization;
Correct option is C
 What property has the
output signal of a scalar quantizer
·
The output is a discrete signal
with a countable symbol alphabet (but not necessarily a finite symbol
alphabet).
·
The output is a discrete signal
with a finite symbol
·
The output signal may be discrete
or continuous
Correct option is A
UnitV
 Characteristic of a
vector quantizer
 Multiple quantization
indexes are represented by one codeword
 Each input symbol is
represented by a fixedlength codeword
 Multiple input
symbols are represented by one quantization index
 All of the
above
Correct option is C
 Vector quantization
is rarely used in practical applications, why?
 The coding efficiency
is the same as for scalar quantization
 The computational
complexity, in particular for the encoding, is much higher than in scalar
quantization and a large codebook needs to be stored
 It requires block
Huffman coding of quantization indexes, which is very complex
 All of the
above
Correct option is B
 Let N represent the
dimension of a vector quantizer. What statement about the performance of
the best vector quantizer with dimension N is correct?
 For N approaching
infinity, the quantizer performance asymptotically approaches the rate
distortion function (theoretical limit)
 By doubling the
dimension N, the bit rate for the same distortion is halved
 The vector quantizer
performance is independent of N
 All of the
above
Correct option is A
 Which of the
following is/are correct for the advantage of vector quantization over
scalar quantization.
 Vector Quantization
can lower the average distortion with the number of reconstruction levels
held constant
 Vector Quantization
can reduce the number of reconstruction levels when distortion is held
constant
 Vector Quantization
is also more effective than Scalar Quantization When the source output
values are not correlated
 All of the above
Correct option is D
 Vector quantization
is used for
 Lossy data
compression
 Lossy data correction
 Pattern recognition
 All of the
above
Correct option is D
 The Linde–Buzo–Gray
algorithm is a
quantization algorithm to derive a good codebook.
 Scalar
 Vector
 Both
 None of the
above
Correct option is B
 Vector quantization
is used in
 Video coding
 Audio coding
 Speech coding
 All of the above
Correct option is C
 What are processes
(Techniques) used in video coding?
 Partition of frames
into macroblocks
 Form of Vector
Quantization
 Both (A) & (B)
 None of these
Correct option is C
 The process of
converting the analog sample into discrete form is called
 Modulation
 Multiplexing
 Quantization
 Sampling
Correct option is C
10 . The sequence of operations in
which PCM is done is
 Sampling, quantizing,
encoding
 Quantizing, encoding,
sampling
 Quantizing, sampling,
encoding
 None of the above
Correct option is A
 To convert a
continuous sensed data into Digital form, which of the following is
required?
A. Sampling
B. Quantization
C. Both Sampling and Quantization
D. Neither Sampling nor Quantization
Correct option is C
 For a continuous
image f(x, y), Quantization is defined as
A. Digitizing the coordinate values
B. Digitizing the amplitude values
C. All of the mentioned
D. None of the mentioned
Correct option is B
 The resulting image
of sampling and quantization is considered a matrix of real numbers. By
what name(s) the element of this matrix array is called
 Image element or
Picture element
 Pixel or Pel
 All of the mentioned
 None of the mentioned
Correct option is C
 Which conveys more
information?
A. High probability event
B. Low probability event
C. High & Low probability event
D. None of the mentioned
Correct option is B
 The probability
density function of the envelope of narrow band noise is
A. Uniform
B. Gaussian
C. Rayleigh
D. Rician
Correct option is B
 Which model is known
as ignorance model?
A. Physical model
B. Markov model
C. Probability model
D. Composite Source Model
Correct option is C
 Shannons theorem is
also called
A. noiseless coding theorem
B. noisy coding theorem
C. coding theorem
D. noiseless theorem Answer
Correct option is A
 Transform coding,
vector quantization are examples for
A. Pixel
B. compression
C. Transmission
D. Lossy compression Answer
Correct option is D
19. Entropy Coding is
an
 Lossless
 Lossy
 0
 None
Correct option is A
20. is
normally used for the data generated by scanning the documents, fax machine,
typewriters etc.
 Huffman Coding
 Transformation Coding
 Vector Quantization
 Runlength Encoding
Correct option is D
21. Compression Technique used in Image
Video is
 Huffman Coding
 Transformation Coding
 Entropy Coding
 Differential Encoding
Correct option is B
22. Compression Technique used in Audio
is
 Differential Encoding
 Transformation
Encoding
 Entropy Coding
 Differential &
Transformation Encoding
correct option is D
23. Expansion of LZ Coding is
 Lossy
 Lossless
 Lempelzivwelsh
 Lempelziv
Correct option is D
24. Expansion of LZW Coding is
 Lossy
 Lossles
 Lempelziv
 Lempelzivwelsh
Correct option is D
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