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BoxFilter.hpp
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BoxFilter.hpp
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#ifndef BOXFILTER_HPP_
#define BOXFILTER_HPP_
#include "math/Box.hpp"
#include "Pixmap.hpp"
namespace Tungsten {
template<typename Texel>
void boxFilterSlow(const Pixmap<Texel> &src, Pixmap<Texel> &result, int R, Box2i subImage = Box2i())
{
if (subImage.empty())
subImage = Box2i(Vec2i(0), Vec2i(src.w(), src.h()));
int x0 = subImage.min().x(), x1 = subImage.max().x();
int y0 = subImage.min().y(), y1 = subImage.max().y();
for (int y = y0; y < y1; ++y) {
for (int x = x0; x < x1; ++x) {
Texel sum(0.0f);
int pixelCount = 0;
for (int dy = -R; dy <= R; ++dy) {
for (int dx = -R; dx <= R; ++dx) {
int xp = x + dx;
int yp = y + dy;
if (xp >= x0 && xp < x1 && yp >= y0 && yp < y1) {
sum += src(xp, yp);
pixelCount++;
}
}
}
result(x, y) = sum/pixelCount;
}
}
}
template<typename Texel>
void boxFilter(const Pixmap<Texel> &src, Pixmap<Texel> &tmp, Pixmap<Texel> &result, int R, Box2i subImage = Box2i())
{
if (subImage.empty())
subImage = Box2i(Vec2i(0), Vec2i(src.w(), src.h()));
int x0 = subImage.min().x(), x1 = subImage.max().x();
int y0 = subImage.min().y(), y1 = subImage.max().y();
if (x1 - x0 < 2*R || y1 - y0 < 2*R) {
boxFilterSlow(src, result, R, subImage);
return;
}
float factor = 1.0f/(2*R + 1);
for (int y = y0; y < y1; ++y) {
Texel sumL(0.0f);
Texel sumR(0.0f);
for (int x = 0; x < 2*R; ++x) {
sumL += src(x0 + x, y);
sumR += src(x1 - 1 - x, y);
if (x >= R) {
tmp(x0 + x - R , y) = sumL/(x + 1);
tmp(x1 - 1 - (x - R), y) = sumR/(x + 1);
}
}
for (int x = x0 + R; x < x1 - R; ++x) {
sumL += src(x + R, y);
tmp(x, y) = sumL*factor;
sumL -= src(x - R, y);
}
}
for (int x = x0; x < x1; ++x) {
Texel sumL(0.0f);
Texel sumR(0.0f);
for (int y = 0; y < 2*R; ++y) {
sumL += tmp(x, y0 + y);
sumR += tmp(x, y1 - 1 - y);
if (y >= R) {
result(x, y0 + y - R) = sumL/(y + 1);
result(x, y1 - 1 - (y - R)) = sumR/(y + 1);
}
}
for (int y = y0 + R; y < y1 - R; ++y) {
sumL += tmp(x, y + R);
result(x, y) = sumL*factor;
sumL -= tmp(x, y - R);
}
}
}
}
#endif /* BOXFILTER_HPP_ */