Design of Two Template Cellular Neural Networksfor Color Image Processing
Yasuteru Hosokawa

Yoko Uwate and Yoshifumi Nishio

Dept. of Media and Information Systems,
Shikoku University
Furukawa, Ohjin, Tokushima, Japan
hosokawa@keiei.shikoku-u.ac.jp

Dept. Electrical and Electronic Engineering,
Tokushima University
2-1 Minami-Josanjima, Tokushima, Japan{uwate, nishio}@ee.tokushima-u.ac.jp

Abstract— In this study, TTCNNs for color image processing
were designed. In this design, Bayer arrangement is applied toTTCNNs. Some simulation results were shown for a possibility ofone-layer color image processing using TTCNNs.
Keywords; Cellular Neural Networks; Color Image Processing;Bayer FilterI.
INTRODUCTION
One of important advantages of Cellular Neural Networks(CNNs) [1][2] is a simple and uniform structure. The simpleand uniform structure makes an IC implementation of CNNs
easily. However, almost all modified CNNs proposed by many
researchers became complicated systems by the modify.

Figure 1. System Model of TTCNN.

Two Template CNNs (TTCNN) [3], which are one kind of
Modified CNNs, keeps the simple and uniform structure of aconventional CNN. The difference from a conventional CNN
is the number of signal lines for cloning template values only.
The structure of one Cell is the same. Therefore, the simple
and uniform structure is kept.

State equation of Cell beta:
dxij
=dt

Output function:yij = 0.5(|xij + 1|

In this study, TTCNNs for color image processing aredesigned. In order to process a color image, Bayerarrangement, which is a well-known arrangement of a color
filter array of an image sensor, is applied to TTCNNs. By thisdesign, TTCNNs can process color image by one layer. Thus,
this design has a possibility of hardware coupling an image
sensor and TTTCNN.

XA↵ (i, j; k, l)ykl +XB↵ (i, j; k, l)ukl|xijXB (i, j; k, l)ukl(2)

c(k,l)

1|).

(3)

A. Bayer Arrangement
Bayer arrangement patented by Bryce E. Bayer in 1975 is akind of color image filter. Photo diodes used in an image
sensor can obtain strength of light only. Therefore, in order toprocessing a color image, processing three primary colors isneeded. Bayer arrangement can process three primary colors
on one photo diodes array. This arrangement is used in almost
all one-layer color image sensors because it is very simple andit can be realized with low costs.

State equation of Cell alpha:c(k,l)

A (i, j; k, l)ykl +III. COLOR IMAGE PROCESSING BY TTCNNIn this section, Bayer arrangement and its application toTTCNN are described. Bayer arrangement is very simple as
one-layer color image processing. This arrangement is used inalmost all image sensors of one-layer. By applying thisarrangement to TTCNN, one-layer color image processing ofTTCNN can be realized.

TWO TEMPLATE CELLULAR NEURAL NETWORKS
Figure 1 shows a system model of Two Template CNN(TTCNN). Different cloning template values can be set
between Cell alpha and Cell beta. Arrangement of two kinds ofcells is a checkered pattern. In case of applied same cloning
template values, this system becomes same as a conventional
CNN. The difference from a conventional CNN is only thispoint. Therefore, TTCNN has an almost same structure as aconventional CNN. This feature means that the simple anduniform structure of a conventional CNN is kept. Stateequations are described as follows.

xij + I↵ +X

c(k,l)

Only some subscripts of state equations are different froma conventional CNN. Thus, the characteristic and structure ofcells is same as a conventional CNN. Some template sets forthis system were proposed in [6].

II.

dxij=dt

xij + I +(1)c(k,l)

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(a) Input image(b) Simulation result of (4)Figure 2. Bayer arrangement.

Processing of Bayer filter is as follows. First, an input
image is filtered by Bayer arrangement as shown in Fig. 2.
Next, each color pixel data is generated using four filteredpixels data which are a red, a blue, and two green. This process
is known as demosaicing. The number of obtained color image
data is equal to the number of photo diodes minus boundary
pixels because filtered pixels data excepted boundary pixels isused four times. We can obtain color image data from twosteps processing only.

(c) Simulation result of (5) (d) Simulation result of (6)Figure 3. Simulation results of applying CIE 1931 xy color space diagram [5].

B. Applying Bayer arrangement to TTCNN
Bayer arrangement is similar to cell arrangement ofTTCNN. Cell alpha of TTCNN is corresponding to Red orBlue of Bayer arrangement. Cell beta is corresponding toGreen. Hence, Bayer arrangement is applied to TTCNN forcolor image processing. Some of simulation results are shownin Figs. 3 and 4.
Figures 3 show some simulation result of applying CIE
1931 xy color space diagram [5] as an input image. Fig. 3 (a) is
the input image. Figure 3 (b)-(d) are simulation results in caseof applying following cloning template values, respectively.
01A↵ = @11111I↵ = 0,00 12A↵ = @10 1

111A ,
1I↵ =2,1.6
A↵ = @1.4
1.6

1.4
0.8
1.40I↵ = 0.6,01
A =@ 1
1101A ,
0

1
11 A,
1

10.5
1

I = 1012 1 2
A = @1 1 1 A ,
2 1 2

11.6
1.4A ,
1.6

I =101A = @1.8
101B↵ = @ 01111.8A ,
1

1.8
0.4
1.8

I = 0.100B↵ = @0001004000B↵ = @0.60100A ,001
B = @01010110A ,1110 A,101
B = @01010110A ,
10.6
20.6

100.6A ,001
B =@ 1
111.6
1(a) Input image

Figure 4. Simulation results of a picture of a sky, a forest, and a river.

IV. CONCLUSION
In this study, TTCNNs for color image processing aredesigned. In order to process a color image, Bayerarrangement, is applied to TTCNNs. By this design, it wasconfirmed that TTCNNs can process color image by one layer.
This result shows a possibility of hardware coupling an image
sensor and TTTCNN.

(4)ACKNOWLEDGMENT(5)

This work was partly supported by JSPS Grant-in-Aid for
Scientific Research 16K06357.

1
11A ,
1REFERENCES(6)[1]In Fig. 3 (b), purple is extracted. In Fig. 3 (c), cyan andyellow are extracted. In Fig. 3 (d), white is extracted as purple.
Another case is shown in Figs. 4. Figure 4 (a) shows aninput image which shows a sky, a forest, and a river. Figure 4(b) is a simulation result in case of applying following cloning
template values.
03A↵ = @ 3
2154I↵ = 3,

123A ,
503
A = @33I =242
1

123A ,
002B↵ = @33

144

1
13 A,
502
B =@ 3
534
4

[2]
[3]

[4]

122A ,
3[5](7)[6]

The forest part is recognized clearly as orange color. Thus,
processing some simple color image can be confirmed.

978-1-5386-7960-9/18/$31.00 ©2018 IEEE(b) Simulation result of (7)163

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