superPixels算法

/*--- function cw = ic(emag,ephase,ci,cj,mask) Input: emag = matrix of image size, edge magnitudes ephase = phase map for edges, discrete values [ci,cj] = c index representation for entries in the pairwise affinity matrix mask = label matrix of image size, pixels of the same value have affinity of 1 regardless of emag and ephase Output: cw = real vector of the same size as ci, maximum emag of intervening contours Stella X. Yu, July 9 2003. --*/ # include "mex.h" # include "math.h" void mexFunction( int nargout, mxArray *out[], int nargin, const mxArray *in[] ) { /* declare variables */ int nr, nc, np, total, to_bias; int k, a, ai, aj, b, bi, bj, p, pi, pj, q, qi, qj, di, dj, s, step; double z, maxe, slope; unsigned int *ci, *cj; double *emag, *phase, *cw, *mask; /* check argument */ if (nargin<4) { mexErrMsgTxt("Four input arguments required"); } if (nargout>1) { mexErrMsgTxt("Too many output arguments"); } /* get pb and phase */ nr = mxGetM(in[0]); nc = mxGetN(in[0]); a = mxGetM(in[1]); b = mxGetN(in[1]); total = mxGetM(in[2]) * mxGetN(in[2]); np = mxGetM(in[3]) * mxGetN(in[3]) - 1; if ( nr != a || nc != b || nr*nc != np || np<=0) { mexErrMsgTxt("Dimension mismatches between the inputs"); } emag = mxGetData(in[0]); phase = mxGetData(in[1]); /* get the c-index pair */ if (!mxIsUint32(in[2]) || !mxIsUint32(in[3])) { mexErrMsgTxt("Index pair shall be of type UINT32"); } ci = mxGetData(in[2]); cj = mxGetData(in[3]); /* get the mask */ to_bias = 0; if (nargin>4) { a = mxGetM(in[4]); b = mxGetN(in[4]); if (a*b>0) { if (a==nr && b==nc && mxIsDouble(in[4])) { to_bias = 1; mask = mxGetData(in[4]); } else { mexErrMsgTxt("Incorrect size or type for mask"); } } } /* create output */ out[0] = mxCreateDoubleMatrix(total,1,mxREAL); if (out[0]==NULL) { mexErrMsgTxt("Not enough memory for the output matrix"); } cw = mxGetPr(out[0]); /* computation */ for (a=0; a<np; a++) { aj = a / nr; /* col */ ai = a % nr; /* row */ for (k=cj[a]; k<cj[a+1]; k++) { b = ci[k]; maxe = 0.0; if (!((a==b) || (to_bias && mask[a]==mask[b] && mask[a]>0 && to_bias))) { bj = b / nr; bi = b % nr; /* (p,q): adjacent pixels moving along the line connecting a and b */ p = a; pj = aj; pi = ai; /* scan */ dj = abs(aj - bj); di = abs(ai - bi); if (dj >= di) { /* step along j */ step = (bj>aj) ? 1 : -1; slope = (float)(bi-ai) / (float)(bj-aj); for (s=0; s<dj; s++) { qj = pj + step; qi = (int) (0.5 + slope * (qj-aj) + ai); q = qi + qj * nr; if (1) { z = emag[p]; if (z>maxe) { maxe = z; } } p = q; pj = qj; pi = qi; } } else { /* step along i */ step = (bi>ai) ? 1 : -1; slope = (float) (bj-aj) / (float)(bi-ai); for (s=0; s<di; s++) { qi = pi + step; qj = (int) (0.5 + slope * (qi-ai) + aj); q = qi + qj * nr; if (1) { z = emag[p]; if (z>maxe) { maxe = z; } } p = q; pj = qj; pi = qi; } } maxe = maxe * 0.5; } cw[k] = maxe; } /* b */ } /* a */ }