Function erode

tests/validation/reference/Erode.cpp:41–79

{
template <typename T>
SimpleTensor<T> erode(const SimpleTensor<T> &src, BorderMode border_mode, T constant_border_value)
{
    /*
             -1   x  +1
         -1 [tl][tc][tr] -1
          y [ml][xy][mr]  y
         +1 [bl][bc][br] +1
             -1   x  +1
        erode:
        dst(x, y) = min[ src(x', y') for x-1<=x'<=x+1, y-1<=y'<=y+1 ] = min({tl, tc, tr, ml, xy, mr, bl, bc, br})
    */
    SimpleTensor<T> dst(src.shape(), src.data_type());

    const uint32_t num_elements = src.num_elements();
#if defined(_OPENMP)
#pragma omp parallel for
#endif /* _OPENMP */
    for (uint32_t i = 0; i < num_elements; ++i)
    {
        Coordinates coord = index2coord(src.shape(), i);
        const int   x     = coord.x();
        const int   y     = coord.y();

        std::array<T, 9> neighbours = {{0}};
        for (int row = y - 1, j = 0; row <= y + 1; ++row)
        {
            for (int col = x - 1; col <= x + 1; ++col, ++j)
            {
                coord.set(0, col);
                coord.set(1, row);
                neighbours[j] = tensor_elem_at(src, coord, border_mode, constant_border_value);
            }
        }

        dst[i] = *std::min_element(neighbours.cbegin(), neighbours.cend());
    }

    return dst;
}

template SimpleTensor<uint8_t>
erode(const SimpleTensor<uint8_t> &src, BorderMode border_mode, uint8_t constant_border_value);