A Novel and Fast Adaptive Compressive Sampling Matching
Pursuit Algorithm
Jian Zhao
1*
, Tingting Lu
1
, Jian Jia
2
, Chao Zhang
1
, Weiwen Su
1
, Rui Wang
1
, Shunli Zhang
1
1
School of Information Science and Technology, Northwest University, Xian, PR China,710127
2
Deparment of Mathematics, Northwest University, Xi’an, PR China,710127
zjctec@nwu.edu.cn
Keywords: Compressive Sensing; Adaptive; Compressive Sampling Matching Pursuit.
Abstract: A weakness of compressive sampling is that it needs the information of sparsity to approximate the
compressible signal. In this paper, an fast iterative reconstruction algorithm called Adaptive Compressive
Sampling Matching Pursuit is presented to solve the problem mentioned above, which delivers the same
guarantees as the best optimization-based approaches and get rid of the dependence on the information of
sparsity. Experimental results also demonstrate that the image reconstructed performance of the proposed
algorithm is improved in terms of PSNR, SNR and reconstructed time, compared to Orthogonal Matching
Pursuit (OMP) and Compressive Sampling Matching Pursuit (CoSaMP).
1 INTRODUCTION
Compressive sensing (CS) (Donoho, 2006) (Candes
and Wakin, 2008) (Baraniuk, 2007) is a relatively
novel theory in signal sampling, which is based on
sparse or compressible signal. Reconstruction
algorithm (Candes et al, 2006) is one of the most
active and challenging part of compressive sensing,
which is of great significance to accurately
reconstruct the signal and verify the sampling
accuracy.
However, current reconstruction algorithms
based on compressive sensing also have drawbacks.
Matching Pursuit (MP) algorithm (Mallet and Zhang,
1993) needs to go through multiple iterations to
obtain convergence, since the results of each iteration
may be sub-optimal due to non-orthogonal projection
of the signal on the selected atom sets (measurement
matrix column vector). To overcome the drawback of
MP, TroPP J et al. proposed Orthogonal Matching
Pursuit (OMP) (TroPP and Gilbert, 2007). But
OMP’s theoretical guarantee which ensures accurate
reconstruction is weaker than the minimum
1
l -norm
approach, so not all signals can be reconstructed
accurately. On the basis of OMP, Needell et al.
(Needell and Vershynin, 2009) and Donoho et
al.( Donoho et al, 2009) proposed Regularized
Orthogonal Matching Pursuit (ROMP) and Stagewise
Orthogonal Matching Pursuit (StOMP), respectively.
Their computing speeds are faster and their
reconstruction complexities are lower, compared to
OMP; yet their properties are poor. As a result, M
must be large enough to obtain better reconstructed
performance of the signal. Needen et al. proposed
Compressive Sampling Matching Pursuit (CoSaMP)
(Needell and TroPPJ, 2009). The algorithm offers
rigorous bounds on computational cost and storage. It
is likely to be extremely efficient algorithm for
practical problems because it requires only matrix
vector-multiplies with the sampling matrix. These
algorithms are built on the basis of known sparsity
K
, yet the sparsity
K
is often unknown in a practical
application.
In this paper, we propose a improved
reconstruction algorithm named Adaptive-CoSaMP
based on CoSaMP, according to the prior information
that reconstruction algorithm needs sparsity of
sampling signal (Davenport,M.A. and Wakin,M.B.,
2010). Property measures, such as PSNR and
reconstruct time, are used to evaluate the performance
of the proposed algorithm. Simulation results of
Adaptive-CoSaMP are compared with that of
CoSaMP and OMP.
Be advised that papers in a technically
unsuitable form will be returned for retyping. After
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modified.
312
312
Jia J., Zhao J., Zhang C., Lu T., Su W., Wang R. and Zhang S.
A Novel and Fast Adaptive Compressive Sampling Matching Pursuit Algorithm.
DOI: 10.5220/0006449603120317
In ISME 2016 - Information Science and Management Engineering IV (ISME 2016), pages 312-317
ISBN: 978-989-758-208-0
Copyright
c
2016 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
2 COMPRESSIVE SAMPLING
To enhance intuition, we focus on sparse and
compressible signals. For vectors x in
, the
0
l
“quasi-norm” (Candes and Romberg, 2007) is defined
by
0
sup ( ) { : 0}
j
xpxjx== (2.1)
A signal x is called s-sparse if
sx
0
. Compressible
signals are well approximated by sparse signals. In
compressive sampling theory, a sample is a linear
functional applied to a signal. The process of
collecting multiple samples is best viewed as the
action of a sampling matrix
Φ on the target signal. If
we take
m
samples or measurements of a signal in
, then dimension of the sampling matrix Φ is
mN×
.
The minimum number of measurements satisfies
2ms
on account of the following simple
argument. The sampling matrix must not map two
different s-sparse signals to the same set of samples.
Therefore, each collection of
2s
columns from the
sampling matrix must be nonsingular. As a result,
some sparse signals are mapped to very similar sets
of samples, and it is unstable to invert the sampling
process numerically. Instead, Candes and Tao
proposed the stronger condition that the geometry of
sparse signals should be preserved under the action of
the measurement matrix (Needell and TroPPJ, 2009).
To quantify this idea, they defined the
r th restricted
isometry constant of a matrix
Φ
as the least number
r
δ
for which
22 2
22 2
(1 ) +
rr
x
xx
δδ
−≤Φ 1
whenever
0
x
r
(2.2)
We have written
2
for the
2
l vector norm.
When
1
r
δ
< , these inequalities imply that each
collection of
r columns from Φ is nonsingular,
which is the minimum requirement for acquiring
(r/2)-sparse signals. When
≪1 , the sampling
operator very nearly maintains the
2
l distance
between each pair of (r/2)-sparse signals. In
consequence, it is possible to invert the sampling
process stably.
3 AN ADAPTIVE COMPRESSIVE
SAMPLING MATCHING
PURSUIT ALGORITHM
Compressive Sampling Matching Pursuit (CoSaMP)
is proposed by Candes and Donoho (Needell and
Vershynin, 2009). The CoSaMP algorithm selects the
reserved atom based on the known sparsity of the
approximation to be produced and removes a fixed
number of atoms combining backward thought, so
computing speed of each iteration of the CoSaMP
algorithm is slow to some extent. In this section, an
Adaptive-Compressive Sampling Matching Pursuit is
proposed based on CoSaMP. The algorithm gets rid
of the dependence on sparsity, reconstructs the
original signal through adaptively adjusting the step
size in iteration, and has less reconstruct time.
The algorithm is initialized with a trivial signal
approximation, which means that the initial residual
equals the unknown target signal. During each
iteration, Adaptive-CoSaMP performs five major
steps:
(1) Identification. The algorithm forms a proxy of the
residual from the current samples and locates the
3t
largest components of the proxy.
(2) Support Merger. The set of newly identified
components is united with the set of
3t
largest
components that appear in the current
approximation.
(3) Estimation. The algorithm solves a least-squares
problem to approximate the target signal on the
merged set of components.
(4) Pruning. The algorithm produces a new
approximation by retaining only the
t largest
entries in this least-squares signal approximation.
(5) Sample Update. Finally, the samples are updated
so that they reflect the residual, the part of the
signal that has not been approximated.
The main source code of the proposed algorithm
is summarized in Table 1.
4 EXPERIMENTAL RESULTS
AND DISCUSSION
In this section, the peak signal-to-noise ratio (PSNR)
and SNR (signal-to-noise ratio) are used to evaluate
the visual quality of the reconstructed image
F
ˆ
.
PSNR is defined as
A Novel and Fast Adaptive Compressive Sampling Matching Pursuit Algorithm
313
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313
dB
MSE
PSNR )
255
(log20
10
= , (4.1)
and SNR is defined as
dB
MSE
jiF
SNR )
),(
ˆ
(log20
10
= , (4.2)
where MSE is the mean square error between the
original image F and the reconstructed image
F
. It
is given by
∑∑
=
=
=
1
0
1
0
2
)],(
ˆ
),([
1
M
i
N
j
jiFjiF
MN
MSE
. (4.3)
To further evaluate the effectiveness of the
proposed algorithm, the proposed algorithm is
compared with existing algorithm proposed in
reference (TroPP and Gilbert, 2007) and in reference
(Needell et al, 2009). Figure 2, Figure 3, Figure 3,
Figure 4 and Table 2 show the comparative results of
two test images
Lena (
256256 × ) and Barbara( 256256 × ).
Table 1 The main source code of the Adaptive-CoSaMP algorithm
Adaptive-CoSaMP algorithm
Input: Measurement matrix Φ , Sampling vector
y
, halting criterion
ε
, iteration
k
Output: An sparse approximation
ˆ
x
of the target signal
Residual
0
ry=
Initial step
1t =
Index set of values A=
,
S =∅
stage=0
0k =
repeat
1kk←+
() * ( 1)kk
gr
←Φ {Form signal proxy}
()
3
sup ( )
k
t
Spg {Identify large components}
A
AS←∪
{Merge supports}
*1*
|
|(( ) )
AA
b
y
←ΦΦ Φ
{Signal estimation by least-squares}
|0
C
A
b
ˆ
kt
b {Prune to obtain next approximation}
(1)
ˆ
kk
k
rr x
=−Φ {Update current samples}
1
s
tage stage=+
*t stage t=
until halting criterion true
Table 2 SNR, PSNR and reconstructed time comparison between our proposed method and method in (TroPP and Gilbert,
2007)and(Needell et al, 2009) for host images in the case of compression ratio respectively 0.4 and 0.5
Compression ratio (0.5) Compression ratio (0.4)
Reference
(TroPP and
Gilbert ,
2007)
Reference
(Needell
et al,
2009)
Proposed
algorithm
Referenc
e (TroPP
and
Gilbert ,
2007)
Referenc
e(Needell
et al,
2009)
Proposed
algorithm
Lena
PSNR 31.59 30.85 33.84 25.18 26.45 29.09
SNR 16.00 17.39 18.99 8.31 9.22 9.5
Time 69.35 70.72 55.19 18.64 8.67 7.08
Barbara
PSNR 29.79 31.06 31.66 21.24 20.48 21.22
SNR 14.46 16.56 18.11 6.54 6.54 8.79
Time 79.24 75.12 57.64 21.94 9.15 7.64
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(a) (b)
Figure 1.Original images:(a) Lena image; (b) Barbara image
(a) OMP (b) CoSaMP (c)Adaptive-CoSaMP
Figure 2.Reconstructed images of Lena image in the case of compression ratio 0.5
(a) OMP (b) CoSaMP (c)Adaptive-CoSaMP
Figure 3.Reconstructed images of Barbara image in the case of compression ratio 0.5
(a) OMP (b) CoSaMP (c)Adaptive-CoSaMP
Figure 4.Reconstructed images of Lena image in the case of compression ratio 0.4
From the Table 2, we can observe that our
algorithm has higher SNR values and PSNR values
for all the compression ratio of reconstruction,
compared to algorithms in (TroPP and
Gilbert , 2007)
and. (Davenport,M.A. and Wakin,M.B., 2010) And
the reconstructive time of the scheme is less than that
of reference (TroPP and Gilbert , 2007) and
reference(Needell et al, 2009). From Figure 2, Figure
3, Figure 4 and Figure 5, it is not hard to observe that
A Novel and Fast Adaptive Compressive Sampling Matching Pursuit Algorithm
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315
(a) OMP (b) CoSaMP (c)Adaptive-CoSaMP
Figure 5.Reconstructed images of Lena image in the case of compression ratio 0.4
proposed algorithm has better visual qualities of the
reconstructed images, compared to algorithms in
reference (TroPP and Gilbert, 2007) and
reference(Needell et al, 2009). Hence we can
conclude that the proposed algorithm-Aaptive-
CoSaOMP algorithm is superior to other algorithms
for reconstructing signal .
5 CONCLUSION
In this paper, we discuss compressive sampling theory
which is one of the most active and challenging
subject in signal processing in recent years. Taking
advantage of the greedy iterative algorithm often-
used in compressive sensing, an improved matching
pursuit algorithm—Adaptive-CoSaMP algorithm,
which is based on compressive sampling matching
pursuit algorithm, is proposed. The proposed
algorithm not only allows a accurate reconstruction of
signal in the case of unknown sparsity K, but also can
gradually update to approximate the original signal by
setting the step value. Simulation results also shows
that the improved algorithm has significantly
improvement in reconstruction effect of the image
whether from the visual effects of the reconstructed
image or from the PSNR value of the reconstructed
image.
ACKNOWLEDGEMENTS
This work was supported by National Natural Science
Foundation of China (No. 6137901061572400) and
Natural Science Basic Research Plan in Shaanxi
Province of China (No.2015JM6293).
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