contra based fusion

8/3/2019 Contra Based Fusion

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MEDICAL IMAGE FUSION


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Introduction to Image Processing

image processing is any form of signal processing forwhich the input is an image, such as photographs or

frames of video.

The output of image processing can be either an

image or a set of characteristics or parameters

related to the image.

Image-2D Matrix

To process the Image we are taking MATLAB


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Image Processing Applications

Computer vision Face detection

Feature detection

Medical image processing Microscope image processing

Morphological image processing

Remote sensing Transmission in Broadcast


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Medical Image Applications

Image Segmentation

Micro calcification Detection

Image Fusion

Image Compression


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Objective

To improve the edge information in Image.

Fuse the edge information with the help of comparing the

contrast values.

To get the high information Image.


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Image Fusion

Image Fusion is the process of combining relevantinformation from two or more images into a single image.

The fused image should have more complete information

which is more useful for human or machine perception. The resulting image will be more informative than any of

the input images.

Medical fusion image is to combine functional image (CT)

and anatomical image (MRI) together into one image . This image can provide abundance information to doctor to

diagnose clinical disease.


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Need of Image Fusion

Several situations in image processing require high spatialand high spectral resolution in a single image.

Most of the available equipment is not capable of

providing such data convincingly. The image fusion techniques allow the integration of

different information sources.

The fused image can have complementary spatial and

spectral resolution characteristics.


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Basic Diagram of Fusion


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MRI & CT Images

Magnetic resonance imaging (MRI) is primarily a medicalimaging technique most commonly used in radiology tovisualize the structure and function of the body.

MRI provides much greater contrast between the different

soft tissues of the body than computed tomography (CT)does, making it especially useful in neurological (brain).

Unlike CT, it uses no ionizing radiation, but uses apowerful magnetic field to align the nuclear magnetizationof (usually) hydrogen atoms in water in the body.

Radiofrequency fields are used to systematically alter thealignment of this magnetization, causing the hydrogennuclei to produce a rotating magnetic field detectable bythe scanner.


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Continuous..

This signal can be manipulated by additional magneticfields to build up enough information to construct animage of the body.

The body is mainly composed of water molecules whicheach contain two hydrogen nuclei or protons.

When a person goes inside the powerful magnetic field ofthe scanner these protons align with the direction of the

field.

A second radiofrequency electromagnetic field is then

briefly turned on causing the protons to absorb some of itsenergy.

When this field is turned off the protons release this energyat a radiofrequency which can be detected by the scanner.


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Continuous..

Computed tomography (CT) is a medical imaging methodemploying tomography.

Tomography is imaging by sections or sectioning. Digital geometry processing is used to generate a three-

dimensional image of the inside of an object from a large

series of two-dimensional X-ray images taken around a

single axis of rotation.

CT is a sensitive method for diagnosis of abdominal

diseases. It is used frequently to determine stage of cancer.


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Block Diagram

Image 1

Image 2

DWT

DWT

LaplacianbasedFusion

IDWT

Fused Image


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DCT

DCT- Discrete Cosine Transform

Here It separates the Image to number of blocks.

In these blocks first block has the low frequency

information.

We can see clear information in

low frequency sub band.

DC

horizontale

dges

vertical edges


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Drawbacks of DCT

Only spatial correlation of the pixels inside the single 2-D

block is considered and the correlation from the pixels of

the neighboring blocks is neglected

Impossible to completely decorrelate the blocks at theirboundaries using DCT

Undesirable blocking artifacts affect the reconstructed

images or video frames.


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DWT Sub band Structure

L

H

2

L

H

L

H

LL

LH

HL

HH

2

2

2

2

2


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INPUT IMAGE


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1st Level DWT


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1st Level DWT Output


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2nd Level DWT


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2nd Level DWT Output


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Discrete Wavelet Transform

Wavelet Transform is a type of signal representation thatcan give the frequency content of the signal at a particularinstant of time or spatial location.

Wavelet analysis has advantages over traditional Fouriermethods in analyzing physical situations where the signalcontains discontinuities.

Discrete wavelet transform has more efficiency compare

with DCT.


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Advantages of DWT over DCT

No need to divide the input coding into non-overlapping 2-

D blocks, it has higher compression ratios avoid blocking

artifacts.

Allows good localization both in time and spatialfrequency domain.

Better identification of which data is relevant to human

perception.


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Laplacianbased Fusion Rule

Wavelet multi-resolution expression maps the

image to different level of pyramid structure of

wavelet coefficient based on scale and direction.

To implement wavelet transform image fusion

scheme, first, to construct the wavelet coefficient

pyramid of the two input images.

Second, to combine the coefficient information ofcorresponding level. Finally, to implement inverse

wavelet transform using the fused coefficient.


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Advantages..

The Contrast' method and the proposed fusion

method presents lightly better visual effect than the

others.

Especially, the proposed method has less disturbing

details and has smooth edges such as the outlines of

skulls and brain tumor.


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Applications

Image Classification

Aerial and Satellite imaging

Medical imaging

Battle field Monitoring

Concealed weapon detection

Digital Camera Applications

contra based fusion

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