Published in IET Image Processing
Received on 4th October 2011
Revised on 12th January 2013
Accepted on 14th February 2013
doi: 10.1049/iet-ipr.2012.0554
ISSN 1751-9659
Effective two-step method for face hallucination based
on sparse compensation on over-complete patches
Mohamed Naleer Haju Mohamed
1,2
, Yao Lu
1
, Feng Lv
1
1
Beijing Laboratory of Intelligent Information Technology, School of Computer Science, Beijing Institute of Technology,
Beijing 100081, People’s Republic of China
2
Faculty of Applied Sciences, South Eastern University of Sri Lanka, Amparai 3220, Sri Lanka
E-mail: hmmnaleer@gmail.com
Abstract: Sparse representation has been successfully applied to image d using low- and high-resolution training face images
based on sparse representation. In this study, the sparse residual compensation is adopted to face hallucination. Firstly, a
global face image is constructed by optimal coefficients of the interpolated training images. Secondly, the high-resolution
residual image (local face image) is found by using an over-complete patch dictionary and the sparse representation. Finally,
a hallucinated face image is obtained by combining these two steps. In addition, the more details of the face image in high
frequency parts are recovered using a residual compensation strategy. In the authors’ experimental work, it is observed that
balance sparsity parameter (λ) has affected the residual compensation. Further, the proposed algorithm can acquire a high-
resolution image even though the number of training image pairs is comparatively smaller. The experiments show that the
authors’ method is more effective than the other existing two-step face hallucination methods.
1 Introduction
In the past few years, many researchers focused on sparse
representation and compressive sensing. Survey on the
theory and algorithms of compressed sensing and sparse
representation has been seen in [1–4]; Donoho and Tanner
[1] provide an elegant geometric interpretation of classical
compressed sensing theory and results, revealing a strong
connection to high-dimensional combinatorial geometry and
providing a precise characterisation of under-sampling
bounds. Cande’s and Plan [2] introduce a more recent trend
of extending the study from recovery of sparse signals to
the completion of low-rank matrices, in which the
sparsity-prompting l
1
-norm is replaced with the low-rank
promoting nuclear norm of a matrix. This work proves the
stability of matrix completion under noise.
Tropp and Wright [3] give a comprehensive review of many
algorithms that had been developed in the past few years for
sparse signal recovery. Cevher et al. [4] demonstrate how
the basic sparse signal model can be extended or generalised
to broader classes of low-dimensional models with similar
efficient and accurate signal reconstruction. These models
are applicable to wider range of applications. Some of the
conventional applications of compressive sensing in signal
processing, including images, are stated in [5, 6] in detail.
The surveys by Elad and Aharon [5] provide both
conceptual and empirical justifications why sparse and
redundant representations are crucial for image processing.
Sparsity-promoting techniques are very effective for many
classical tasks such as image denoising, inpainting,
super-resolution etc. Fadili et al.[6] apply sparse
representation to more specific image processing problem of
decomposing image into multiple unknown components.
Sparsity promoting and compressive sensing techniques
have tremendous effect on a broader range of engineering
fields, including but not limited to pattern recognition,
machine learning, communications, sensor networks and
image processing [7–10]; Wright et al.[7] survey some of
the early successful applications of sparse representations in
computer vision, especially in face recognition. It shows
that special settings of the practical problems lead to new
mathematical models and results that enrich the basic theory
of sparse representation. Rubinstein et al.[8] address the
important problem how to automatically learn a dictionary
from raw samples that are adaptive to the signals or data of
interest. Also, a comprehensive survey of some of the most
popular and effective algorithms for learning dictionary has
been stated by Bajwa et al.[9] shows how compressed
sensing can be used to estimate the parameters of the
communication channels. Yang et al.[10] demonstrate how
sparse representation can be used for event detection and
classification with sensor netw orks.
Recently, the super-resolution is a very active research area.
It aims to overcome some of the inherent resolution
boundaries of low-cost imaging sensor. Such resolution
enhancing skill may also be crucial in judgement or
investigation from low-quality images and the related
practical techniques can also be extremely complicated.
Inspection systems is yet another application that is being
paid more attention, it can provide very significant
information about the tracked objects such as criminals and
license plates.
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The Institution of Engineering and Technology 2013 doi: 10.1049/iet-ipr.2012.0554