Image Registration (2D) using Mutual Information (Optimization toolbox needed)

[2D Mutual Information Matching using Optimization toolbox]

This is an updated automatic image registration using mutual information for users of IP toolbox coded by Kateryna Artyushkova from The University of New Mexico.

The object function 'image_registr_MI.m' was originally coded by the person and modified by me.

I added a scale factor for complete image registration using Optimization toolbox. Therefore, the Optimization toolbox is required to run this program.

The zip file contains three files.

- opti_MI_scaling.m % Main code
- image_registr_MI.m % Object function
- image.mat % Image matrics

In 'image.mat', IM1 and IM2 were included only for example purpose.

- IM1: 230 X 230 MRI 8-bit image
- IM2: 512 X 512 CT 8-bit image

To run this code, enter the commands as follows:

>> x0=[50; 50; -15; 0.5];
>> [x, fval]=fminsearch(@image_registr_MI,x0)

OR

Run 'opti_MI_scaling' without any options to see an example.

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Your selection of initial point, x0, is critical for this matching.

-x0(1): First index of row for cropping the rotated IM2 with x0(3) angle
-x0(2): First index of column for cropping the rotated IM2 with x0(3) angle
-x0(3): Angle
-x0(4): Scale factor

Select them as close to the final matching points as possible; otherwise the matching will fail.

The 'fminsearch' function in the Optimization Toolbox is used. The objection function for this optimization technique is 'image_registr_MI.m'

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Data types
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The pixel size of IM1 is bigger than IM2 and the image size of IM1 is smaller than that of IM2. Every image should be 8-bit gray scale image. If not, you must change it.