// Apply a Gaussian filter of size filtersz - separable implementation
private MultiDimFloatTexture applyGaussianFilter_Separable(int filtersz)
{
// . compute Gauss kernel
MultiDimFloatTexture kernel = new MultiDimFloatTexture(filtersz, 1, 1);
float sum = 0;
for (int i = 0; i < filtersz; i++)
{
float di = (float)(i - filtersz / 2);
float u2 = (di * di) / ((float)filtersz * filtersz);
float sigma = 1.0f / 3.0f; // > 3 std dev => assume 0
kernel.set((float)Math.Exp(-u2 / (2.0f * sigma * sigma)), i, 0, 0);
sum += kernel.get(i, 0, 0);
}
// . normalize
for (int i = 0; i < filtersz; i++)
{
kernel.set(kernel.get(i, 0, 0) / sum, i, 0, 0);
}
// . alloc result and tmp buffer (initialized to 0)
MultiDimFloatTexture tmp = new MultiDimFloatTexture(m_iW, m_iH, m_iNumComp);
MultiDimFloatTexture res = new MultiDimFloatTexture(m_iW, m_iH, m_iNumComp);
// . convolve - pass 1 (treat texture as toroidal)
for (int v = 0; v < m_iH; v++)
{
for (int u = 0; u < m_iW; u++)
{
for (int i = 0; i < filtersz; i++)
{
int x = u + i - filtersz / 2;
int y = v;
for (int c = 0; c < numComp(); c++)
{
float val = tmp.get(u, v, c);
tmp.set(val + ((float)getmod(x, y, c)) * kernel.get(i, 0, 0), u, v, c);
}
}
}
}
// . convolve - pass 2 (treat texture as toroidal)
for (int v = 0; v < m_iH; v++)
{
for (int u = 0; u < m_iW; u++)
{
for (int j = 0; j < filtersz; j++)
{
int x = u;
int y = v + j - filtersz / 2;
for (int c = 0; c < m_iNumComp; c++)
{
float val = res.get(u, v, c);
res.set(val + ((float)tmp.getmod(x, y, c)) * kernel.get(j, 0, 0), u, v, c);
}
}
}
}
kernel = null;
tmp = null;
return(res);
}
