没有合适的资源?快使用搜索试试~ 我知道了~
首页一篇图像分割的外文论文,可供大家学习
一篇图像分割的外文论文,可供大家学习

一篇图像分割的外文论文,对彩色图像分割方法的现状进行了深入的回顾; 此外,还介绍了一些使用图像分割方法的重要应用。 最后,展示了经常用于评估定量分割图像的一组度量。可供大家学习
资源详情
资源评论
资源推荐

Neurocomputing 292 (2018) 1–27
Contents lists available at ScienceDirect
Neurocomputing
journal homepage: www.elsevier.com/locate/neucom
Segmentation of images by color features: A survey
Farid Garcia-Lamont
a
,
∗
, Jair Cervantes
a
, Asdrúbal López
b
, Lisbeth Rodriguez
c
a
Universidad Autónoma del Estado de México, Centro Universitario UAEM Texcoco, Av. Jardín Zumpango s/n, Fraccionamiento El Tejocote, CP 56259,
Texcoco-Estado de México, México
b
Universidad Autónoma del Estado de México, Centro Universitario UAEM Zumpango, Camino viejo a Jilotzingo continuación Calle Rayón, CP 55600,
Zumpango-Estado de México, México
c
Instituto Tecnológico de Orizaba, División de Investigación y Estudios de Posgrado, Av. Oriente 9, 852. Col. Emiliano Zapata, CP 94320, Orizaba-Veracruz,
México
a r t i c l e i n f o
Article history:
Received 13 August 2017
Revised 30 October 2017
Accepted 8 January 2018
Available online 7 March 2018
Communicated by Chennai Guest Editor
Keywords:
Color spaces
Image segmentation
Quantitative evaluation
a b s t r a c t
Image segmentation is an important stage for object recognition. Many methods have been proposed in
the last few years for grayscale and color images. In this paper, we present a deep review of the state
of the art on color image segmentation methods; through this paper, we explain the techniques based
on edge detection, thresholding, histogram-thresholding, region, feature clustering and neural networks.
Because color spaces play a key role in the methods reviewed, we also explain in detail the most com-
monly color spaces to represent and process colors. In addition, we present some important applications
that use the methods of image segmentation reviewed. Finally, a set of metrics frequently used to evalu-
ate quantitatively the segmented images is shown.
©2018 Elsevier B.V. All rights reserved.
1.
Introduction
Image segmentation is one of the most important object recog-
nition stages for artificial vision systems. Image segmentation is
defined as the union of sets that contains the pixels coordinates
with an specific feature; in other words, let I
s
= ∪
n
i =1
R
i
be the seg-
mented image, such that ∩
n
i =1
R
i
= ∅ , where n is the number of
segments and R
k
=
(i, j) ∈ N
2
| I(i, j) = δ
k
, being I ( i, j ) the value
of the pixel located in ( i, j ) of the input image I and δ
k
is the kth
threshold value [25] . That is, the segmentation consists on group-
ing the pixels according to specific features of the object to recog-
nize; such as texture, shape, color, among others [173] . Segmen-
tation of images by color features has been addressed or stud-
ied recently. The algorithms for color image segmentation have
been developed because color features may provide relevant data
about the objects within the image. These algorithms have been
applied in different areas such as medicine [9,55,127,160,193] and
food analysis [47,108,111] , among others [7,14,33,74,137,169,174] .
Many of the techniques developed for image segmenta-
tion in gray scale have been extended for color images
[34,95,114,147,158,172,197] ; however, such techniques cannot be al-
ways successfully applied, because they are designed to process
∗
Corresponding author.
E-mail addresses: fgarcial@uaemex.mx (F. Garcia-Lamont),
jcervantesc@uaemex.mx (J. Cervantes), alchau@uaemex.mx (A. López),
lrodriguez@itorizaba.edu.mx (L. Rodriguez).
mainly the intensity of the colors without considering the chro-
maticity. Therefore, the algorithms for color image segmentation
must be developed taking into account the characteristics of color.
For color processing, it is important to select an adequate mathe-
matical representation of color, such that all the features of color
can be processed independently; basically, the most important fea-
tures of color are intensity and chromaticity [49] . There are differ-
ent color spaces to represent color; selecting a color space depends
on its characteristics, the way the color is contemplated to be pro-
cessed and the nature of the method employed for color process-
ing. For instance, the RGB color space is adequate for image dis-
playing, but not for color processing, because the intensity is not
decoupled from the chromaticity. Thus, in this paper we present
the color spaces more often used in related works, the character-
istics of these color spaces are described and we compare their
advantages and disadvantages. An important part of the segmen-
tation stage is the quantitative evaluation of the segmented image.
So far, there have not been defined standard metrics for quanti-
tative evaluation of color image segmentation. Therefore, in this
survey we present a set of metrics for quantitative evaluation of
color image segmentation; these metrics are often employed to
evaluate quantitatively the segmentation of color images The rest
of this paper is divided as follows: in Section 2 the most common
color spaces employed for image segmentation are presented; in
addition their characteristics, advantages and disadvantages are de-
scribed. In Section 3 the segmentation techniques for color images
of previous works are introduced and reviewed. In Section 4 a set
https://doi.org/10.1016/j.neucom.2018.01.091
0925-2312/© 2018 Elsevier B.V. All rights reserved.

2 F. Garcia-Lamont et al. / Neurocomputing 292 (2018) 1–27
of metrics widely used for quantitative evaluation of color image
segmentation are presented. Section 5 shows some applications of
color image segmentation. Finally, Section 6 closes the paper with
conclusions.
2. Color spaces
The goal of a color space is to ease the specification of colors
within a tridimensional coordinated system, or form a subspace of
the system where every color is represented by a unique point.
Most of the color spaces employed are oriented to hardware de-
vices, such as monitors, printers, or applications for color manip-
ulations, like creation of graphics for animation. The usual mod-
els oriented to hardware are RGB (red, green, blue) for monitors
and video cameras; CMY (cyan, magenta, yellow) for printers, and
YIQ (where Y is brightness and I and Q are chromatic components)
which is the standard for television [49] .
In the literature, the color spaces for color image processing are
the following: RGB, HSV (hue, saturation, value), HSI (hue, satura-
tion, intensity), L
∗
a
∗
b
∗
, L
∗
u
∗
v
∗
, YUV and YCbCr. Table 9 shows the
color spaces employed in different previous works to represent and
process colors.
The RGB space is adequate for color displaying, for instance, it
is widely employed for television systems and image acquisition;
although this is space is often employed for color recognition, the
RGB space is not suitable for segmentation or color processing, be-
cause of the high correlation between the components R, G and
B. There are other spaces that do not have this problem, but they
have their respective disadvantages. Next we present the features
of the RGB, HSV, HSI, L
∗
a
∗
b
∗
, L
∗
u
∗
v
∗
, YUV and YCbCr color spaces;
as well as, the equations to map colors between the RGB space and
the color spaces mentioned.
2.1. RGB space
In this space every color is represented with the spectral com-
ponents of red, green and blue. The origin of this model can be
found in television technology, and it can be considered as the
fundamental representation of color for computers, digital cameras
and scanners; but also, for image storage. Most of the software de-
veloped for image processing and graphics employ this model. In
the RGB model the combination of colors is based on the addition
of the individual components considering as base the black color.
The process can be considered as the combination of three rays
of color red, green and blue. The intensity of the different compo-
nents of color determines both the hue and the brightness of the
resulting color [49] . The shape of the RGB space is a cube, whose
coordinates correspond to the three basic colors: red (r), green (g)
and blue (b). The values of each component are in the range [0,
255] ⊂ , where every possible color corresponds to a point within
the cube; but, usually the range of values of each color compo-
nent are normalized to the range [0, 1]; hence, space color is rep-
resented as the unit cube shown in Fig. 1 .
The colors red, green and blue constitute the coordinate axis;
different colors are obtained by combining the values of the coor-
dinate axis. Table 2 shows the combination values of the axis for
usual colors.
The RGB space is a simple model, in several studies it is em-
ployed for color processing or when it is necessary to transform
colors to a different color space.
2.2. HSV space
In the HSV space, the color is represented with the components
hue (h), saturation (s) and value (v). Hue is the chromatic feature
that describes a pure color; for instance, yellow, orange, red, etc.
Fig. 1. RGB space represented as a unit cube.
Table 1
Color spaces employed for color image segmentation in different works.
Color space References
RGB [8,22,30,51,68,72,94,106,108,119,136,142,146,157,165,170]
HSV [30,67,69,100,105,118,137,150,189]
HSI [30,67,69,100,105,118,137,150,189]
L
∗
a
∗
b
∗
[22,30,66,81,94,139,185]
L
∗
u
∗
v
∗
[30,125,155,160,165,191,193]
YUV [23,26,27,80,181,186]
YCbCr [44,80,105,109,143,145]
Table 2
Usual colors and their corresponding red, green and blue values.
Color R G B
Black 0 0 0
Red 1 0 0
Yellow 1 1 0
Green 0 1 0
Cyan 0 1 1
Blue 0 0 1
Magenta 1 0 1
White 1 1 1
Gray
1
2
1
2
1
2
Table 3
Usual colors and their corresponding hue, saturation and value parameters.
Color H S V
Black Undefined 0 0
Red 0 1 255
Yellow
π
3
1 255
Green
2
3
π 1 255
Cyan
π 1 255
Blue
4
3
π 1 255
Magenta
5
3
π 1 255
White Undefined 0 255
Gray Undefined 0 127
Table 4
Usual colors and their corresponding hue, saturation and intensity parameters.
Color H S V
Black Undefined 0 0
Red 0 1 255
Yellow
π
3
1 255
Green
2
3
π 1 255
Cyan
π 1 255
Blue
4
3
π 1 255
Magenta
5
3
π 1 255
White Undefined 0 255
Gray Undefined 0 127

F. Garcia-Lamont et al. / Neurocomputing 292 (2018) 1–27 3
Table 5
Usual colors and their corresponding L
∗
, a
∗
and b
∗
parameters.
Color L
∗
a
∗
b
∗
Black 0 0 0
Red 100 128 128
Yellow 100 0 128
Green 100 −127 128
Cyan 100 −127 0
Blue 100 −127 −127
Magenta 100 128 0
White 100 0 0
Gray 50 0 0
Fig. 2. HSV color space.
Saturation is a measure of how the hue is diluted in white light;
value is the intensity or brightness of the color. The HSV space has
two important features [49,69] :
1. The intensity component, value, is decoupled from the hue
data;
2. The hue and saturation components emulate the human per-
ception of color. With these features the HSV space becomes
a useful tool to develop image processing algorithms based on
some properties of the human color perception.
The hue is in the range [0, 2 π ] ⊂ ; saturation is in the real
range [0, 1], while value is often in the range [0, 255] ⊂ . The HSV
space is cone shaped, as shown in Fig. 2 . Geometrically, the radius
and the height of the cone represent the saturation and value com-
ponents, respectively.
Note that for colors black, white and gray, the hue parameter
is undefined, due to these colors are considered as singularities
within this color space; because they do not have a specific chro-
maticity.
2.3. HSI space
The HSI space, represented with the components hue (h), sat-
uration (s) and intensity (i), is very similar to the HSV space. De-
spite the similarity, computing their components, hue, saturation
and the intensity, is different with respect to how same compo-
nents are obtained in the HSV space. The ranges of the components
are the same than the ranges of the components of the HSV space.
That is, the hue is in the range [0, 2 π] ⊂ ; saturation is in the
real range [0, 1], while intensity is in the range [0, 255] ⊂ . The
Fig. 3. HSI color space.
HSI space is double cone shaped, as shown in Fig. 3 . Geometrically,
the radius and the height of the cone represent the saturation and
intensity components, respectively [49] .
For both spaces HSV and HSI, the same hue and saturation pa-
rameters are employed to represent colors, except for brightness,
where in each space the parameters are different.
2.4. CIE XYZ space
The standard model XYZ, developed by the Comisin Interna-
tionale dclairage, is the base of most of the calibrated color models
employed nowadays. The calibrated color models are employed to
reproduce the colors independently of the display devices. Several
problems happen because there is a strong dependence between
the device and the reproduction of images. All the color spaces
described before are related to the physic measures of the output
devices employed to display images; for instance, the configurable
parameters of a laser printer. The color model is developed by sev-
eral measures performed under strict conditions. The model con-
sists of three basic colors X, Y and Z; they are selected such that,
through positive components all the colors and combinations can
be described. This space is perceived as no linear by humans. That
is, in some parts of the space, huge color changes are produced
before little position variations; while in other parts of the space
happens the opposite, little color changes are experimented for
large position changes [49] . Thus, variations of the CIE model have
been developed for different kinds of applications, or to repre-
sent the colors such that it mimics the human perception of color.
Examples of CIE variations are the spaces YUV, YCbCr, L
∗
u
∗
v
∗
and
L
∗
a
∗
b
∗
; in this study we address the spaces L
∗
u
∗
v
∗
, L
∗
a
∗
b
∗
, YUV
and YCbCr because they are often employed for color image pro-
cessing.
2.4.1. CIE L
∗
a
∗
b
∗
space
This color space is developed considering linearizing the tonal-
ity changes, where the colors are defined by three variables: L
∗
is
the intensity, a
∗
and b
∗
are the tonality components [49,66] . The
value of a
∗
defines the distance through red-green axis, while the
value of b
∗
defines the distance through the blue-yellow axis. Usu-
ally a
∗
and b
∗
are in the ranges [ −127 , 128] ⊂ and L
∗
in the range
[0, 100] ⊂ .
The shape of this space is similar to the RGB space, but the
location of colors is different, see Fig. 4 .
Note that in this space, similarly to the HSV and HSI spaces, the
intensity is decoupled from the chromaticity, mimicking the way

4 F. Garcia-Lamont et al. / Neurocomputing 292 (2018) 1–27
Fig. 4. L
∗
a
∗
b
∗
color space.
Table 6
Usual colors and their corresponding L
∗
, u
∗
and v
∗
parameters.
Color L
∗
u
∗
v
∗
Black 0 0 0
Red 53 175 37
Yellow 94 7 106
Green 84 −83 107
Cyan 88 −70 −15
Blue 29 −9 −130
Magenta 57 80 −108
White 100 0 0
Gray 50 0 0
Table 7
Usual colors and their corresponding Y, U and V parameters.
Color Y U V
Black 0 0 0
Red 0.299 −0.147 0.615
Yellow 0.886 −0.436 0.1
Green 0.587 −0.289 −0.515
Cyan 0.701 0.147 −0.615
Blue 0.114 0.436 −0.1
Magenta 0.413 0.289 0.515
White 1 0 0
Gray 0.5 0 0
the humans perceive the colors
[69] . But also, because of the tonal-
ity changes are linear, the chromaticity differences can be com-
puted using the Euclidean distance.
2.4.2. CIE L
∗
u
∗
v
∗
space
This space is similar to the CIE L
∗
a
∗
b
∗
space, where the colors
are represented by the intensity component L
∗
and the chromatic
components u
∗
and v
∗
[49] . Usually u
∗
and v
∗
are in the ranges
[ −175 , 175] ⊂ and L
∗
in the range [0, 100] ⊂ . Table 6 shows the
parameters for luminance, and chromaticity for usual colors.
2.4.3. YUV and YCbCr color spaces
The YUV and YCbCr color spaces are employed to standardize
the images for television. The YUV space is the base for color cod-
ing for NTSC system; while the YCbCr is the standard for digi-
tal television. In these models the components that define them
feature three planes: the luminance (Y) and the other two called
chrominance components, (UV and CbCr for spaces YUV and YCbCr,
respectively) [49] . Table 7 shows the luminance and chrominance
parameters for usual colors for the YUV space.
Due to humans are not able to distinguish sharpness with high
precision in colors, and also humans are more sensitive to bright-
ness, the bandwidth can be reduced considerably for the definition
of the color components. This feature is employed by the color
Table 8
Usual colors and their corresponding Y, Cb and Cr parameters.
Color Y Cb Cr
Black 0 0 0
Red 0.299 −0.169 0.5
Yellow 0.886 −0.5 0.081
Green 0.587 −0.331 −0.419
Cyan 0.701 −0.831 −0.5
Blue 0.114 −0.5 −0.081
Magenta 0.413 −0.669 0.419
White 1 −1 0
Gray 0.5 −0.5 0
compression algorithms; for instance, as a part of the compres-
sion algorithm for the JPEG format, the RGB colors are mapped
to the YCbCr space. However, the YCbCr space is widely employed
for image processing, mainly for compression applications, the YUV
model is less used. Table 8 shows the luminance and chrominance
paramaters for usual colors for the YCbCr space.
2.5. Transformations between color spaces
As mentioned before, the hardware devices employed for image
acquisition and display, employ the RGB space to represent colors.
Therefore, it is necessary to map the colors to the color spaces pre-
sented above, in order to process the colors under the features of
such color spaces; and then, to map the resulting colors to the RGB
space so as to display the result of processing. In this section, we
present the equations to map the RGB colors to the color spaces
mentioned before, as well as the inverse mapping [25,49] .
2.5.1. Mapping between RGB and HSV spaces
Mapping a RGB color to the HSV space involves the following
operations. Let ϕ = [ r, g, b] be the RGB color vector, and φ = [ h, s, v ]
the resulting vector by mapping ϕ to the HSV space. The hue, sat-
uration and value are computed with:
θ =
⎧
⎪
⎨
⎪
⎩
und ef ined , r = g = b
cos
−1
(
r − g
)
+
(
r − b
)
2
(
r − g
)
2
+
(
r − b
) (
g − b
)
, ot herwise
(1)
h =
θ
, b ≤ g
2 π − θ, b > g
(2)
s =
0 , max (r, g, b) = 0
1 −
min
(r, g, b)
max (r, g, b)
, ot her wise
(3)
v = max (r, g, b) (4)
The inverse operation, in other words, mapping HSV color vec-
tor φ = [ h, s, v ] to the RGB space involves the following operations.
If h = und ef ined then r = v , g = v and b = v ; otherwise:
r =
⎧
⎪
⎨
⎪
⎩
q, k = 1
p, 2 ≤ k ≤ 3
t, k = 4
v , ot her wise
(5)
g =
⎧
⎪
⎨
⎪
⎩
t, k = 0
v , 1 ≤ k ≤ 2
q, k = 3
p, ot herwise
(6)
b =
⎧
⎪
⎨
⎪
⎩
p, 0 ≤ k ≤ 1
t, k = 2
v , 3 ≤ k ≤ 4
q, ot herwise
(7)

F. Garcia-Lamont et al. / Neurocomputing 292 (2018) 1–27 5
where
k =
3
π
h
(8)
f =
3
π
h − k (9)
p = v × (1 − s ) (10)
q = v ×
(
1 − (s × f )
)
(11)
t = v ×
(
1 − (s × (1 − f ))
)
(12)
2.5.2. Mapping between RGB and HSI spaces
Mapping a RGB color to the HSI space involves the following
operations. Let ϕ = [ r, g, b] be the RGB color vector, and ψ = [ h, s, i ]
the resulting vector by mapping ϕ to the HSI space. The hue is
computed with Eqs. (1) and (2), while saturation and intensity are
computed with:
s = 1 −
min
(r, g, b)
i
(13)
i =
r + g + b
3
(14)
The inverse operation, in other words, mapping HSI color vector
ψ = [ h, s, i ] to the RGB space involves the following operations. If
h = und ef ined then r = i, g = i and b = i else: If 0 ≤ h <
2 π
3
then
b = i (1 − s ) (15)
r = i
⎡
⎣
1 +
s cos h
cos (
π
3
− h )
⎤
⎦
(16)
g = 3 i (1 − r − b) (17)
If
2 π
3
≤ h <
4 π
3
then
r = i (1 − s ) (18)
g = i
⎡
⎢
⎣
1 +
s cos
h −
2
3
π
cos (π − h )
⎤
⎥
⎦
(19)
b = 3 i
(
1 − r − g
)
(20)
If
4
3
π ≤ h < 2 π then
g = i (1 − s ) (21)
b = i
⎡
⎢
⎣
1 +
s cos
h −
4
3
π
cos
5
3
π − h
⎤
⎥
⎦
(22)
r = 3 i
(
1 − g − b
)
(23)
2.5.3. Mapping between RGB and L
∗
a
∗
b
∗
spaces
Mapping a RGB color to the L
∗
a
∗
b
∗
is performed with the fol-
lowing equations. Let ϕ = [ r, g, b] be a color represented in the RGB
space:
L
∗
= 116 f
Y
Y
re f
− 16 (24)
a
∗
= 500
f
X
X
re f
− f
Y
Y
re f
(25)
b
∗
= 200
f
Y
Y
re f
− f
Z
Z
re f
(26)
X
Y
Z
=
0 . 4124 0 . 3575 0 . 1804
0 . 2126 0 . 7151 0 . 0721
0 . 0193 0 . 1191 0 . 9502
r
g
b
(27)
where δ =
6
29
and
f (t) =
3
√
t , t > δ
3
t
3 δ
2
+
4
29
, t ≤ δ
3
(28)
The inverse operation is performed with the following opera-
tions:
X = X
re f
h
L
∗
+ 16
116
+
a
∗
500
(29)
Y = Y
re f
h
L
∗
+ 16
116
(30)
Z = Z
re f
h
L
∗
+ 16
116
−
b
∗
200
(31)
where
h (t) =
t
3
, t > δ
3 δ
2
t −
4
29
, t ≤ δ
(32)
r
g
b
=
0 . 4124 0 . 3575 0 . 1804
0 . 2126 0 . 7151 0 . 0721
0 . 0193 0 . 1191 0 . 9502
−1
X
Y
Z
(33)
The values X
ref
, Y
ref
and Z
ref
are obtained by substituting the
tristimulus values for the reference white.
2.5.4. Mapping between RGB and L
∗
u
∗
v spaces
Mapping a RGB color to the L
∗
u
∗
v
∗
is obtained with the follow-
ing equations. Let Ï,g,b] be a color represented in the RGB space:
L
∗
=
⎧
⎪
⎪
⎪
⎨
⎪
⎪
⎪
⎩
29
3
3
Y
Y
re f
,
Y
Y
re f
≤ δ
3
116
Y
Y
re f
1
3
− 16 ,
Y
Y
re f
> δ
3
(34)
u
∗
= 13 L
∗
u
− u
re f
(35)
v
∗
= 13 L
∗
v
− v
re f
(36)
u
=
4 X
X + 15 Y + 3 Z
(37)
v
=
9 Y
X + 15 Y + 3 Z
(38)
剩余26页未读,继续阅读















安全验证
文档复制为VIP权益,开通VIP直接复制

评论1