FloatImageView* med_filter(const T &src, size_t region_size)
{
if ((region_size < 1) || (region_size > std::min(src.nrows(), src.ncols())))
throw std::out_of_range("median_filter: region_size out of range");
size_t half_region_size = region_size / 2;
typename ImageFactory<T>::view_type* copy = ImageFactory<T>::new_view(src);
FloatImageData* data = new FloatImageData(src.size(), src.origin());
FloatImageView* view = new FloatImageView(*data);
for (coord_t y = 0; y < src.nrows(); ++y) {
for (coord_t x = 0; x < src.ncols(); ++x) {
// Define the region.
Point ul((coord_t)std::max(0, (int)x - (int)half_region_size),
(coord_t)std::max(0, (int)y - (int)half_region_size));
Point lr((coord_t)std::min(x + half_region_size, src.ncols() - 1),
(coord_t)std::min(y + half_region_size, src.nrows() - 1));
copy->rect_set(ul, lr);
view->set(Point(x, y), image_med(*copy));
}
}
delete copy;
return view;
}
FloatImageView* variance_filter(const T &src,
const FloatImageView &means,
size_t region_size)
{
if ((region_size < 1) || (region_size > std::min(src.nrows(), src.ncols())))
throw std::out_of_range("variance_filter: region_size out of range");
if (src.size() != means.size())
throw std::invalid_argument("variance_filter: sizes must match");
size_t half_region_size = region_size / 2;
// Compute squares of each element. This step avoid repeating the squaring
// operation for overlapping regions.
FloatImageData* squaredData = new FloatImageData(src.size(), src.origin());
FloatImageView* squares = new FloatImageView(*squaredData);
transform(src.vec_begin(),
src.vec_end(),
squares->vec_begin(),
double_squared<typename T::value_type>());
FloatImageData* data = new FloatImageData(src.size(), src.origin());
FloatImageView* view = new FloatImageView(*data);
for (coord_t y = 0; y < src.nrows(); ++y) {
for (coord_t x = 0; x < src.ncols(); ++x) {
// Define the region.
Point ul((coord_t)std::max(0, (int)x - (int)half_region_size),
(coord_t)std::max(0, (int)y - (int)half_region_size));
Point lr((coord_t)std::min(x + half_region_size, src.ncols() - 1),
(coord_t)std::min(y + half_region_size, src.nrows() - 1));
squares->rect_set(ul, lr);
// Compute the variance.
FloatPixel sum
= std::accumulate(squares->vec_begin(),
squares->vec_end(),
(FloatPixel)0);
size_t area = squares->nrows() * squares->ncols();
FloatPixel mean = means.get(Point(x,y));
view->set(Point(x, y), sum / area - mean * mean);
}
}
delete squaredData;
delete squares;
return view;
}
