Foreground Object Sensing for Saliency Detection
Hengliang Zhu
1
, Bin Sheng
1
, Xiao Lin
2
, Yangyang Hao
1
, Lizhuang Ma
1
1
Dept. of Computer Science and Engineering, Shanghai Jiao Tong University, China
2
School of Optical-electr ical and Computer Engineering, University of Shanghai for science and technology, China
{hengliang_zhu, haoyangyang2014}@sjtu.edu.cn, lin6008@126.com, {shengbin,
ma-lz}@cs.sjtu.edu.cn
ABSTRACT
Many state-of-the-art saliency detection algorithms rely on the bound-
ary prior, but these algorithms simply suppose the boundaries around
an image as background regions. Here we propose a fast and effec-
tive algorithm for salient object detection. First, a novel method is
proposed to approximately locate the foreground object by using
the convex hull from Harris corner. On this basis, we divide the
saliency values of different regions into two parts and generate the
corresponding cue maps (foreground and background), which are
combined into a convex hull prior map. Then a new prior based
on distance to the convex hull center is proposed to replace the
center prior. Finally, the convex hull prior map and the convex hul-
l center-biased map are combined to be the saliency map, which
is then optimized to get the final result. Compared with eighteen
existing algorithms and tested on several datasets, the present algo-
rithm performs well in terms of precision and recall.
CCS Concepts
•Computing methodologies → Interest point and salient region
detections;
Keywords
Foreground object; Harris corner; Convex hull; Saliency map
1. INTRODUCTION
Following the study on the information processing mechanism
of the biological (human) vision system, the task of visual saliency
detection has rapidly progressed in recent years and is successfully
used in numerous computer vision applications, such as object seg-
mentation [34], image compression [13, 23], image resizing [29],
image retrieval [8,35], and image quality assessment [46]. The aim
of “visual saliency” is to find the abundant information regions of
an image, where the salient regions are perceptually distinguishable
from non-salient regions.
From the psychophysical perspective [22], saliency detection can
be classified into bottom-up (data-driven) methods [7,12,15,32,39,
45,48] and top-down (goal-driven) methods [20,27,47]. In contrast
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DOI: http://dx.doi.org/10.1145/2911996.2912008
to the latter taking advantage of high-level prior knowledge of an
image, the former makes use of low-level features of the image (e.g.
color, location, and texture) to detect saliency regions. With these
primitive features, in the previous works [1, 18, 28, 37, 48], prior
assumptions, such as the center prior, contrast prior, and boundary
prior, were raised to improve the accuracy of salient object detec-
tion. In this paper, we mainly focus on the bottom-up saliency
detection.
In recent years, the image boundary prior is adopted for saliency
detection, assuming that a narrow border of the image is the non-
salient regions. In other words, the image boundary tends to be
background. There are many state-of-the-art algorithms rely on the
boundary prior [19,41,45,48], which achieves better performance.
However, one limitation of these works is that the salient object
may slightly touch the image edge. In other words, the detected
salient object is incomplete at the image boundary regions.
To address this problem, we propose a simple and effective algo-
rithm for saliency region detection (see the workflow inFigure 1).
First, based on the corner detection algorithm (Harris corner [40]),
a new foreground object location algorithm is proposed, which us-
es two convex hull intersections to approximately locate the fore-
ground object. The intersecting region excludes more scattered
background and concentrates on the surrounding of a salient ob-
ject. Second, by incorporating global contrast cues, we introduce a
new region (image patch) saliency computation step (elaborated in
Section 3). We divide the saliency value of a region into two parts:
one part inside of convex hull (salient regions, which may contain
some background) and the other part outside of convex hull (back-
ground regions). They are used to generate two cue maps (fore-
ground and background) that are combined into a convex hull prior
map. Finally, the saliency map is optimized.
The remainder of the article is organized as follows. Section 2
reviews the related work. The details of the proposed saliency com-
putation method is presented in Section 3 and Section 4. Section 5
presents the experimental results and discussions. The conclusions
are given in Section 6.
2. RELATED WORKS
A detailed summary of saliency detection is provided in [4, 5].
The fixation prediction models [3, 11, 14, 16], which track the eye
movements, are based on the exploitation of physical devices. In-
stead, this work is based on the study of image processing. In this
section, we briefly review the major salient detection algorithms
and their differences.
The pioneering research about saliency detection was conducted
by Itti et al. [17], who defined the saliency value of a pixel as the
local center-surround difference. The detection is based on a multi-
scale of image features, including color, intensity, and orientation.