macOS trying to make median mask work :(

[OneDreamCloser]

hello all,

here is an implementation of the median mask along with some parameters:

/* necessary definitions */
#define	M 100
char array1[M] ;
char array2[M] ;

/* initialization */
for( i=0; i<M; i++ )	array1[i] = i ;

/* call median */
median(array1, array2, M, M) ;

/* median filter implementation */
void median(char* imageIn,    
			 char* imageOut,   
			 unsigned width,  
			 unsigned height) {
	const int matrix_size = 9;
	char  values [matrix_size];
	int i;
	
	memset(imageOut, 0, width);
	
	// scan the picture starting at second row
	for (i = width; i < width * (height - 1); i++) {
		// copy first pixels into matrix
		memcpy ((char*)&values,   &imageIn[i-width-1], 3);
		memcpy ((char*)&values+3, &imageIn[i-1],       3);
		memcpy ((char*)&values+6, &imageIn[i+width-1], 3);
		// insertion sort with the matrix
		{
			int x, min;
			char tmp;
			
			for (x=0; x<9; x++) {
				tmp = values[x];
				min = x;
				while ( (min>0) && (values[min-1]>tmp) ) {
					values[min] = values [min-1];
					min--;
				}
				values[min] = tmp;
			}
		}
		// end of insertion sort with the matrix
		// store median value in pixel considered
		imageOut[i] = values[4];
		memset(imageOut+i, 0, width);
	}
}

but i get a segmentation fault when the "memcpy" is called
( the implementation of median is for sure correct, the problem is in the way i use it ),
can someone please help me overcome this ?

thank you

 

[jpyc7]

memcpy ((char*)&values,   &imageIn[i-width-1], 3);

For the above statement, I think you have two choices:
1. Remove the ampersand in the memcpy destination (values).
2. Put in the array location reference, e.g. &(values[0])

I think the fact that you have a cast to char pointer in front meant that the compiler did not give you a warning. So you might want to remove the cast also.

 

[OneDreamCloser]

first of all, thank you jpyc7 for the interest

i tried both ways, but none of them worked,
basically i am worrying about the index of imageIn