INNER CODE UNIT · C
a
chunquedong/mgp · core/3rd/edtaa3func.c:141
a = img[closest]; // Grayscale value at the edge pixel
gx = gximg[closest]; // X gradient component at the edge pixel
gy = gyimg[closest]; // Y gradient component at the edge pixel
if(a > 1.0) a = 1.0;
if(a < 0.0) a = 0.0; // Clip grayscale values outside the range [0,1]
if(a == 0.0) return 1000000.0; // Not an object pixel, return "very far" ("don't know yet")
dx = (double)xi;
dy = (double)yi;
di = sqrt(dx*dx + dy*dy); // Length of integer vector, like a traditional EDT
if(di==0) { // Use local gradient only at edges
// Estimate based on local gradient only
df = edgedf(gx, gy, a);
} else {
// Estimate gradient based on direction to edge (accurate for large di)
df = edgedf(dx, dy, a);
}