} else {
float sum = 0.0f;
for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
- float z = i / radius;
-
// Gaussian blur is a common, but maybe not the prettiest choice;
// it can feel a bit too blurry in the fine detail and too little
// long-tail. This is a simple logistic distribution, which has
// a narrower peak but longer tails.
+ //
+ // We interpret the radius as sigma, similar to Gaussian blur.
+ // Wikipedia says that sigma² = pi² s² / 3, which yields:
+ const float s = (sqrt(3.0) / M_PI) * radius;
+ float z = i / (2.0 * s);
+
weight[i] = 1.0f / (cosh(z) * cosh(z));
if (i == 0) {
float w2 = weight[base_pos + 1];
float offset, total_weight;
- if (w1 + w2 < 1e-6) {
- offset = 0.5f;
- total_weight = 0.0f;
- } else {
- offset = w2 / (w1 + w2);
- total_weight = w1 + w2;
- }
+ combine_two_samples(w1, w2, &offset, &total_weight);
+
float x = 0.0f, y = 0.0f;
if (direction == HORIZONTAL) {