Information Technology Reference
In-Depth Information
11.2.1.3 Color Layout Descriptor (CLD)
This descriptor specifies a spatial distribution of colors in
YC
b
C
r
color space.
It is extracted from the 8 × 8 array of local representative colors, which are
defined by the
DCT
coefficients of color components in one of the 64 parti-
tioned blocks of images or video frames.
The CLD captures the spatial distribution of colors.
The similarity matching for the CLD can be measured by the following
distance function.
Max Number o
{
ffY
Coef
−
1
}
∑
D
=
λ (
Y
Coef
fi Yf
[ ]
−
Coef
[ ])
i
2
Yi
1
2
i
=
0
Max Number of Y
{
Coef
−
1
}
∑
+
λ
(
C
Coef
f
[ ]
i
−
C
Coef
fi
[ ])
(11.9)
2
Ci
b
1
b
2
b
i
=
0
Max Number of Y
{
Coef
−
1
}
∑
+
λ
(
C
Coef
f
[ ]
i
−
C
Coef
fi
[]),
2
Ci
r
1
r
2
r
i
=
0
where the λ's are weights for each coefficient.
11.2.1.4 Color Structure Descriptor (CSD)
This descriptor specifies both color and the structure of color in hue, max,
min, diff (HMMD) color space. It characterizes the relative frequency of
8 × 8 structuring elements that contain image pixels with a particular color
scanning the image, instead of characterizing the relative frequency of indi-
vidual image pixels with a particular color, which is what color descriptors
such as SCD does. This descriptor is capable of distinguishing between
two images of identical amounts of a given color where the structure of the
groups of pixels having that color is different. The CSD containing 256 bins
is extracted directly from the image based on a 256-cell quantization of the
HMMD color space. Those containing 128, 64, and 32 bins are extracted
based on unification of the bins of the 256-bin descriptor. The descriptor
elements are organized in an M element array of 8-bit integer values. The
bins of an M-bin descriptor are associated bijectively to the M quantized
colors of the M-cell color space. For the M = 256 case, the bin value repre-
sents the number of structuring elements in the image that contain one or
more pixels with a color.
The CSD captures the local structure of color.
The similarity matching for CSD can be measured by
L
1
norm.
