1 Removal of Impulse Noise in Images by Means of the Use of Support Vector Machines H. Gómez-Moreno, S. Maldonado-Bascón, F. López-Ferreras, and P. Gil-Jiménez Departamento de Teoría de la Señal y Comunicaciones. Universidad de Alcalá. SPAIN IWANN 2003
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1 Removal of Impulse Noise in Images by Means of the Use of Support Vector Machines H. Gómez-Moreno, S. Maldonado-Bascón, F. López-Ferreras, and P. Gil-Jiménez.
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Removal of Impulse Noise in Images by Means of the Use of Support Vector Machines
H. Gómez-Moreno, S. Maldonado-Bascón, F. López-Ferreras, and P. Gil-Jiménez
Departamento de Teoría de la Señal y Comunicaciones.Universidad de Alcalá.
SPAIN
IWANN 2003
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Presentation of the problem
Due to a noisy transmission channel or to imperfections in the sensor that records the images , an impulse noise appears.
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There are several methods for the recuperation of this noisy images:
1) Median Filter.
State of the art
x-1,y-1 x-1,y x-1,y+1
x,y-1 x,y x,y+1
x+1,y-1 x+1,y x+1,y+1
Ordered values of the pixels included in a 3x3 window
Reconstruction Value
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State of the art
Application of the 3x3 median filter
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State of the art
2) SD-ROM.
x-1,y-1 x-1,y x-1,y+1
x,y-1 x,y x,y+1
x+1,y-1 x+1,y x+1,y+1
Ordered values of the pixels inside a 3x3 window.
If the questioned pixel is far away from the central pixel it is a noisy pixel. Then it is changed.
Ordered values of the pixels inside a 3x3 window excluding the central pixel.
The reconstruction value is the mean value of the central pixels.
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State of the art
Application of the SD-ROM method
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Support Vector Machines (SVMs)
We present an algorithm for impulse noise reduction based on the use of Support Vector Machines (SVMs).
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Application of SVMs to noise reduction
1) We use the SVMs for two tasks:a) Classify the pixels between noisy and not
noisy.
b) Obtain the reconstruction value by means of the SVMs regression.
In the training the values and the support vectors are obtained.
This training is made by minimizing the distance between the decision frontier and the data. In the non linear case it is made in the feature space (non linear transformation).