Matlab C

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Versione del 19 dic 2019 alle 13:16 di Profbevilacqua (Discussione | contributi)

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Irio De Feudis irio.defeudis@poliba.it

Vitoantonio Bevilacqua vitoantonio.bevilacqua@poliba.it

MATLAB C/C++ interface in Visual Studio

Input Image

Code

```
#include "engine.h"
```
```
#include <iostream>
```
```
using namespace std;
```
```
 
```

unsigned char** getRawGrayScaleImage(mxArray *);

void putRawGrayScaleImageInMatlab(unsigned char ** mat, int n);

void countAboveBelowThreshold(unsigned char ** mat, int n, int th);

void invertImage(unsigned char ** mat, int n);

```
 
```
```
//declare pointer to engine
```
```
Engine *eng;
```
```
 
```
```
int main() {
```
```
 
```
```
 
```

	//initialize it with the handle to a new session of MATLAB engine

```
	eng = engOpen(NULL);
```
```
	engSetVisible(eng, 0);
```
```
	//check status 
```
```
	if (!(eng)) {
```
```
		exit(-1);
```
```
	}
```
```
 
```
```
 
```

	//open image in MATLAB engine (using image path)

	engEvalString(eng, "I = imread('C:\\Users\\Irio\\Desktop\\\Esercizio_05122019\\MATLAB&VISUAL STUDIO\\codes\\Heatmap.jpg');");

```
 
```
```
	//show image I
```
```
	engEvalString(eng, "imshow(I)");
```
```
 
```
```
	//wait engine
```
```
	system("PAUSE");
```
```
 
```

	//....manage your matrix in MATLAB (crop and convert)

```
	// MATLAB functions:
```

	// imcrop - creates a crop of the image

	engEvalString(eng, "I = imcrop(I,[276,279,844,844]);");

```
	engEvalString(eng, "imshow(I)");
```
```
 
```
```
	system("PAUSE");
```
```
 
```

	// rgb2gray - convert RGB image or colormap to grayscale.

	engEvalString(eng, "I = rgb2gray(I);");

```
	engEvalString(eng, "imshow(I)");
```
```
 
```
```
	system("PAUSE");
```
```
 
```
```
	//get mxArray of the image (C++ style)
```

	mxArray *imageML = engGetVariable(eng, "I");

	unsigned char **rawimage = getRawGrayScaleImage(imageML);

```
 
```
```
	//....manage your matrix in C++ 
```
```
 
```

	// count and print elements above and below a threshold value

	countAboveBelowThreshold(rawimage, 845, 127);

```
	system("pause");
```
```
 
```
```
	// invert image
```
```
	invertImage(rawimage, 845);
```
```
	system("pause");
```
```
 
```
```
	//put image back in MATLAB
```

	putRawGrayScaleImageInMatlab(rawimage, 845);

```
	//show image
```
```
	engEvalString(eng, "imshow(I)");
```
```
	system("pause");
```
```
 
```
```
	//close the session
```
```
	engClose(eng);
```
```
 
```
```
	return 0;
```
```
}
```
```
 
```
```
//extract image from mxArray pointer
```

unsigned char** getRawGrayScaleImage(mxArray *imagePtr) {

```
 
```
```
	int n = (int)mxGetN(imagePtr);
```
```
 
```

	unsigned char **mat = new unsigned char*[n];

```
	for (int i = 0; i < n; i++)
```
```
		mat[i] = new unsigned char[n];
```
```
 
```
```
	for (int i = 0; i < n; i++)
```
```
		for (int j = 0; j < n; j++) {
```

			mat[i][j] = *((unsigned char*)mxGetData(imagePtr) + i + j*n);

```
		}
```
```
 
```
```
	return mat;
```
```
}
```
```
 
```
```
//create mxArray from image
```

void putRawGrayScaleImageInMatlab(unsigned char ** mat, int n) {

	mxArray *matrix = mxCreateNumericMatrix(n, n, mxUINT8_CLASS, mxREAL);

```
 
```
```
	for (int i = 0; i < n; i++)
```
```
		for (int j = 0; j < n; j++) {
```

			unsigned char *data = (unsigned char*)mxGetData(matrix) + i + j*n;

```
			*data = mat[i][j];
```
```
		}
```
```
 
```
```
	engPutVariable(eng, "I", matrix);
```
```
}
```
```
 
```

// count elements over and under threshold

void countAboveBelowThreshold(unsigned char ** mat, int n, int th) {

```
	int above = 0;
```
```
	int below = 0;
```
```
 
```
```
	for (int i = 0; i < n; i++)
```
```
		for (int j = 0; j < n; j++) {
```
```
			if (mat[i][j] <= th)
```
```
				below++;
```
```
			else
```
```
				above++;
```
```
		}
```
```
 
```
```
	cout << "Threshold: " << th << endl;
```

	cout << "Elements above the threshold: " <<  above << endl;

	cout << "Elements below the threshold: "<< below << endl;

```
}
```
```
 
```
```
// invert image
```

void invertImage(unsigned char ** mat, int n) {

```
 
```
```
	for (int i = 0; i < n; i++)
```
```
		for (int j = 0; j < n; j++) {
```
```
			mat[i][j] = 255 - mat[i][j];
```
```
		}
```
```
}
```

Estratto da "http://www.vitoantoniobevilacqua.it/wiki/index.php?title=Matlab_C&oldid=1187"