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/*=================================================================
* LBPPYR computes LBP features on scale-pyramid of input image.
*
* Synopsis:
* F = lbppyr_mat(I, P)
* where
* I [H x W (uint8)] is input image.
* P [1 x 1 (double)] is height of the scale-pyramid.
* F [N x 1 (uint8)] LBP features stucked to a column vector.
*
*=================================================================*/
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <mex.h>
#include <time.h>
#include <errno.h>
#define MIN(A,B) ((A) > (B) ? (B) : (A))
#define MAX(A,B) ((A) < (B) ? (B) : (A))
#define ABS(A) ((A) < 0 ? -(A) : (A))
#define INDEX(ROW,COL,NUM_ROWS) ((COL)*(NUM_ROWS)+(ROW))
/*======================================================================
Main code plus interface to Matlab.
========================================================================*/
void mexFunction( int nlhs, mxArray *plhs[],int nrhs, const mxArray *prhs[] )
{
uint8_t *I, K;
uint32_t *P;
uint32_t *J;
int w,h,x,y,i,j,N;
int ww,hh;
uint32_t center;
uint32_t offset;
uint8_t pattern;
if( nrhs != 2 )
mexErrMsgTxt("Two input arguments required.\n\n"
"LBPPYR computes LBP features on scale-pyramid of input image.\n"
"Synopsis:\n"
" F = lbppyr(I, P)\n"
"where\n"
" I [H x W (uint8)] is input image.\n"
" P [1 x 1 (double)] is height of the scale-pyramid.\n"
" F [N x 1 (uint8)] LBP features stucked to a column vector. \n");
I = (uint8_t*)mxGetPr(prhs[0]);
K = (uint8_t)mxGetScalar(prhs[1]);
h = mxGetM(prhs[0]);
w = mxGetN(prhs[0]);
/* printf("h: %d\n", h);
printf("w: %d\n", w);
printf("K: %d\n", K);
*/
/* count number of LBPs */
for(ww=w, hh=h, N=0, i=0; i < K && MIN(ww,hh) >= 3; i++)
{
N += (ww-2)*(hh-2);
if(ww % 2) ww--;
if(hh % 2) hh--;
ww = ww/2;
hh = hh/2;
}
K = i;
N = 256*N;
/* printf("N: %d (=256*%d)\n", N,N/256);*/
/* printf("K: %d\n",K);*/
/* printf("%d/%d = %d*%d + %d \n", b,a, a, b/a, b % a);*/
plhs[0] = mxCreateNumericMatrix(N, 1, mxUINT32_CLASS, mxREAL);
P = (uint32_t*)mxGetPr(plhs[0]);
J = mxCalloc(h*w, sizeof(uint32_t));
if(J ==NULL)
mexErrMsgTxt("Not enough memory.");
for(x=0; x < w; x++)
for(y=0; y < h; y++)
J[INDEX(y,x,h)] = I[INDEX(y,x,h)];
for(ww=w, hh=h, i=0, offset = 0; i < K; i++)
{
for(x=1; x < ww-1; x++)
{
for(y=1; y< hh-1; y++)
{
pattern = 0;
center = J[INDEX(y,x,h)];
if(J[INDEX(y-1,x-1,h)] < center) pattern = pattern | 0x01;
if(J[INDEX(y-1,x,h)] < center) pattern = pattern | 0x02;
if(J[INDEX(y-1,x+1,h)] < center) pattern = pattern | 0x04;
if(J[INDEX(y,x-1,h)] < center) pattern = pattern | 0x08;
if(J[INDEX(y,x+1,h)] < center) pattern = pattern | 0x10;
if(J[INDEX(y+1,x-1,h)] < center) pattern = pattern | 0x20;
if(J[INDEX(y+1,x,h)] < center) pattern = pattern | 0x40;
if(J[INDEX(y+1,x+1,h)] < center) pattern = pattern | 0x80;
/* P[cnt++] = pattern; */
P[offset+pattern] = 1;
offset += 256;
}
}
if( i < K-1 )
{
if(ww % 2 == 1) ww--;
if(hh % 2 == 1) hh--;
ww = ww/2;
for(x=0; x < ww; x++)
for(j=0; j < hh; j++)
J[INDEX(j,x,h)] = J[INDEX(j,2*x,h)] + J[INDEX(j,2*x+1,h)];
hh = hh/2;
for(y=0; y < hh; y++)
for(j=0; j < ww; j++)
J[INDEX(y,j,h)] = J[INDEX(2*y,j,h)] + J[INDEX(2*y+1,j,h)];
}
}
return;
}
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