[37] | 1 | /* |
---|
| 2 | max3.c implements ... |
---|
| 3 | |
---|
| 4 | goes through and tests to see if the pixel is a maximum in its 3x3 neighbourhood |
---|
| 5 | |
---|
| 6 | 2001 written by Phil Torr |
---|
| 7 | Microsoft Research Cambridge |
---|
| 8 | */ |
---|
| 9 | |
---|
| 10 | #include <math.h> |
---|
| 11 | #include <stdio.h> |
---|
| 12 | #include "mex.h" |
---|
| 13 | |
---|
| 14 | void mexFunction ( |
---|
| 15 | int nlhs, /* number of expected outputs */ |
---|
| 16 | mxArray **plhs, /* matrix pointer array returning outputs */ |
---|
| 17 | int nrhs, /* number of inputs */ |
---|
| 18 | const mxArray **prhs /* matrix pointer array for inputs */ |
---|
| 19 | ) { |
---|
| 20 | int width, height, i, j, l, k, border =1; |
---|
| 21 | double *out, *in, max; |
---|
| 22 | bool is_max; |
---|
| 23 | |
---|
| 24 | /* parameter checks */ |
---|
| 25 | if ((nrhs != 1) || (nlhs != 1)) { |
---|
| 26 | mexErrMsgTxt ("Usage: Y = max3 (im1)\n\n"); |
---|
| 27 | return; |
---|
| 28 | } |
---|
| 29 | |
---|
| 30 | /* reading the parameters */ |
---|
| 31 | height = mxGetM (prhs [0]); |
---|
| 32 | width = mxGetN (prhs [0]); |
---|
| 33 | in = (double *) mxGetPr (prhs [0]); |
---|
| 34 | |
---|
| 35 | /* require memory for return */ |
---|
| 36 | plhs [0] = mxCreateDoubleMatrix (height, width, mxREAL); |
---|
| 37 | out = (double *) mxGetPr (plhs [0]); |
---|
| 38 | |
---|
| 39 | |
---|
| 40 | //fill in border pixels with a negative... |
---|
| 41 | for (i = 0; i < height; i++) |
---|
| 42 | { |
---|
| 43 | j = 0; |
---|
| 44 | out [j * height + i] = -10001.0; |
---|
| 45 | j = width-1; |
---|
| 46 | out [j * height + i] = -10001.0; |
---|
| 47 | } |
---|
| 48 | |
---|
| 49 | |
---|
| 50 | //fill in border pixels with a negative... |
---|
| 51 | for (j = border; j < width-border; j++) |
---|
| 52 | { |
---|
| 53 | i = 0; |
---|
| 54 | out [j * height + i] = -10001.0; |
---|
| 55 | i = height-1; |
---|
| 56 | out [j * height + i] = -10001.0; |
---|
| 57 | } |
---|
| 58 | |
---|
| 59 | |
---|
| 60 | /* check for maximum */ |
---|
| 61 | for (i = border; i < height-border; i++) |
---|
| 62 | for (j = border; j < width-border; j++) { |
---|
| 63 | max = in [j * height + i]; |
---|
| 64 | is_max = true; |
---|
| 65 | if (max >0.0) |
---|
| 66 | { |
---|
| 67 | /* finding the maximum in the neighbourhood */ |
---|
| 68 | for (l = -border; l < border+1; l++) |
---|
| 69 | for (k = -border; k < border+1; k++) |
---|
| 70 | if (in [(j + l) * height + (i + k)] >= max) { |
---|
| 71 | if ((l!=0) || (k!=0)) |
---|
| 72 | //max = in [(j + l) * height + (i + k)]; |
---|
| 73 | is_max = false; |
---|
| 74 | } |
---|
| 75 | } |
---|
| 76 | else |
---|
| 77 | is_max = false; //if not over threshold, here zero |
---|
| 78 | if (is_max) |
---|
| 79 | out [j * height + i] = max; |
---|
| 80 | else |
---|
| 81 | out [j * height + i] = -10001.0; |
---|
| 82 | } |
---|
| 83 | |
---|
| 84 | return; |
---|
| 85 | } |
---|