static void InitGradMagAndOrientMats(
MAT& magmat, // out: grad mag mat
MAT& orientmat, // out: grad ori mat
const Image& img) // in: ROI scaled to current pyramid level
{
const int nrows = img.rows, nrows1 = img.rows-1;
const int ncols = img.cols, ncols1 = img.cols-1;
const double bins_per_degree = BINS_PER_HIST / 360.;
magmat.create(nrows, ncols);
orientmat.create(nrows, ncols);
for (int y = 0; y < nrows1; y++)
{
const byte* const buf = (byte*)(img.data) + y * ncols;
const byte* const buf_x1 = (byte*)(img.data) + y * ncols + 1;
const byte* const buf_y1 = (byte*)(img.data) + (y+1) * ncols;
double* const magbuf = Buf(magmat) + y * ncols;
double* const orientbuf = Buf(orientmat) + y * ncols;
for (int x = 0; x < ncols1; x++)
{
const byte pixel = buf[x];
const double xdelta = buf_x1[x] - pixel;
const double ydelta = buf_y1[x] - pixel;
magbuf[x] = sqrt(SQ(xdelta) + SQ(ydelta));
double orient =
RadsToDegrees(atan2(ydelta, xdelta)); // -180 <= orient < 180
if (orient < 0)
orient += 360; // 0 <= orient < 360
orientbuf[x] = orient * bins_per_degree; // 0 <= orient < BINS_PER_HIST
}
}
// fill bottom and right edges
magmat.row(nrows1) = 0;
magmat.col(ncols1) = 0;
orientmat.row(nrows1) = 0;
orientmat.col(ncols1) = 0;
}
static void ZapSmallEigs(
MAT& eigvals, // io
MAT& eigvecs) // io
{
const double min = eigvals(0) / 1e6;
CV_Assert(min > 0);
for (int eig = 0; eig < NSIZE(eigvals); eig++)
if (eigvals(eig) < min)
{
eigvals(eig) = 0;
eigvecs.row(eig) = 0; // set all eigenvector elems to 0
}
}