Function GetMagsAndOrients

jni/stasm/hat.cpp:225–259

}

void GetMagsAndOrients( // get mags and orients for patch at ix,iy
    vec_double&       mags,         // out
    vec_double&       orients,      // out
    const int         ix,           // in: x coord of center of patch (may be off image)
    const int         iy,           // in: y coord of center of patch (may be off image)
    const int         patchwidth,   // in: in pixels
    const MAT&        magmat,       // in
    const MAT&        orientmat,    // in
    const vec_double& pixelweights) // in
{
    CV_Assert(patchwidth % 2 == 1);  // patchwidth must be odd in this implementation
    const int npix = SQ(patchwidth); // number of pixels in image patch
    const int halfpatchwidth = (patchwidth-1) / 2;

    mags.resize(npix);
    orients.resize(npix);

    if (ix - halfpatchwidth < 0 || ix + halfpatchwidth >= magmat.cols ||
        iy - halfpatchwidth < 0 || iy + halfpatchwidth >= magmat.rows)
    {
        // Part or all of the patch is out the image area.

        GetMagsAndOrients_GeneralCase(mags, orients,
            ix, iy, patchwidth, magmat, orientmat, pixelweights);
    }
    else
    {
        // Patch is entirely in the image area.  The following function returns
        // results identical to GetMagsAndOrients_GeneralCase, but is faster
        // because it doesn't have to worry about the edges of the image.

        GetMagsAndOrients_AllInImg(mags, orients,
            ix, iy, patchwidth, magmat, orientmat, pixelweights);
    }
}

// Apportion the gradient magnitude of a pixel across 8 orientation bins.
// "Accumulate" is in the func name because we "+=" the interpolated values.