/* Warps image of size w x h, using affine transformation matrix (2x2 part)
and offset (center of warping) ofsx, ofsy. Result is the region of size
defined with roi. */
void warp_image_roi(unsigned char *image, int w, int h, double *H,
double xmin, double xmax, double ymin, double ymax,
double fill, double *result)
{
double curx, cury, curz, wx, wy, wz, ox, oy, oz;
int x, y;
unsigned char *tmp;
double *output=result, i, j, xx, yy;
/* precalulate necessary constant with respect to i,j offset
translation, H is column oriented (transposed) */
ox = M(0,2);
oy = M(1,2);
oz = M(2,2);
yy = ymin;
for (j=0; j<(int)(ymax-ymin+1); j++)
{
/* calculate x, y for current row */
curx = M(0,1)*yy + ox;
cury = M(1,1)*yy + oy;
curz = M(2,1)*yy + oz;
xx = xmin;
yy = yy + 1;
for (i=0; i<(int)(xmax-xmin+1); i++)
{
/* calculate x, y in current column */
wx = M(0,0)*xx + curx;
wy = M(1,0)*xx + cury;
wz = M(2,0)*xx + curz;
// printf("%g %g, %g %g %g\n", xx, yy, wx, wy, wz);
wx /= wz; wy /= wz;
xx = xx + 1;
x = (int)floor(wx);
y = (int)floor(wy);
if (x>=0 && y>=0)
{
wx -= x; wy -= y;
if (x+1==w && wx==1)
x--;
if (y+1==h && wy==1)
y--;
if ((x+1)<w && (y+1)<h)
{
tmp = &image[coord(x,y,w,h)];
/* image[x,y]*(1-wx)*(1-wy) + image[x+1,y]*wx*(1-wy) +
image[x,y+1]*(1-wx)*wy + image[x+1,y+1]*wx*wy */
*output++ =
(*(tmp) * (1-wx) + *nextcol(tmp, w, h) * wx) * (1-wy) +
(*nextrow(tmp,w,h) * (1-wx) + *nextr_c(tmp,w,h) * wx) * wy;
} else
*output++ = fill;
} else
*output++ = fill;
}
}
}
/* main code for each thread -- it computes rows of the product a*b
*/
static void * thread_mult()
{
int n,p;
int m;
double sum;
while ((m=nextrow())!=-1) { /* m=row to do */
for (p=0; p<p_dim; p++) { /* p=col to do, do each col */
for (sum=0.0,n=0; n<n_dim; n++) {
sum += mat_a[m][n]*mat_b[n][p];
}
mat_c[m][p]=sum;
// printf("row %d is,%8.4f/n", m,sum);
}
}
return 0;
}
