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extern crate distance_transform;
use distance_transform::dt2d;
use std::f64;
pub use distance_transform::{FloatGrid, BoolGrid};
#[cfg(feature = "image-utils")]
pub mod utils;
#[cfg(feature = "image-utils")]
mod viridis;
pub fn chanvese(img: &FloatGrid,
init_mask: &BoolGrid,
max_its: u32,
alpha: f64,
thresh: u32) -> (BoolGrid, FloatGrid, u32) {
let mut phi = mask2phi(init_mask);
let mut its = 0u32;
let mut stop = false;
let mut prev_mask = init_mask.clone();
let mut c = 0u32;
while its < max_its && !stop {
let idx = {
let mut result = Vec::new();
for (x, y, &val) in phi.iter() {
if val >= -1.2 && val <= 1.2 {
result.push((x, y));
}
}
result
};
if idx.len() > 0 {
if its % 50 == 0 {
println!("iteration: {}", its);
}
let (upts, vpts) = {
let mut res1 = Vec::new();
let mut res2 = Vec::new();
for (x, y, value) in phi.iter() {
if *value <= 0. {
res1.push((x, y));
}
else {
res2.push((x, y));
}
}
(res1, res2)
};
let u = upts.iter().fold(0f64, |acc, &(x, y)| {
acc + *img.get(x, y).unwrap()
}) / (upts.len() as f64 + f64::EPSILON);
let v = vpts.iter().fold(0f64, |acc, &(x, y)| {
acc + *img.get(x, y).unwrap()
}) / (vpts.len() as f64 + f64::EPSILON);
let f: Vec<f64> = idx.iter().map(|&(x, y)| {
(*img.get(x, y).unwrap() - u)*(*img.get(x, y).unwrap() - u)
-(*img.get(x, y).unwrap() - v)*(*img.get(x, y).unwrap() - v)
}).collect();
let curvature = get_curvature(&phi, &idx);
let dphidt: Vec<f64> = {
let maxabs = f.iter().fold(0.0f64, |acc, &x| {
acc.max(x.abs())
});
f.iter().zip(curvature.iter()).map(|(f, c)| {
f/maxabs + alpha*c
}).collect()
};
let dt = 0.45/(dphidt.iter().fold(0.0f64, |acc, &x| acc.max(x.abs())) + f64::EPSILON);
for i in 0..idx.len() {
let (x, y) = idx[i];
let val = *phi.get(x, y).unwrap();
phi.set(x, y, val + dt*dphidt[i]);
}
phi = sussman(&phi, &0.5);
let new_mask = {
let mut result = BoolGrid::new(phi.width(), phi.height());
for (x, y, value) in phi.iter() {
result.set(x, y, *value <= 0.);
}
result
};
c = convergence(&prev_mask, &new_mask, thresh, c);
if c <= 5 {
its += 1;
prev_mask = new_mask.clone();
}
else {
stop = true;
}
}
else {
break;
}
}
let seg = {
let mut res = BoolGrid::new(phi.width(), phi.height());
for (x, y, &value) in phi.iter() {
res.set(x, y, value <= 0.);
}
res
};
(seg, phi, its)
}
fn bwdist(a: &BoolGrid) -> FloatGrid {
let mut res = dt2d(&a);
for (_, _, value) in res.iter_mut() {
let newval = value.sqrt();
*value = newval;
}
res
}
fn mask2phi(init_a: &BoolGrid) -> FloatGrid {
let inv_init_a = {
let mut result = init_a.clone();
for (_, _, value) in result.iter_mut() {
*value = !*value;
}
result
};
let phi = {
let dist_a = bwdist(&init_a);
let dist_inv_a = bwdist(&inv_init_a);
let mut result = FloatGrid::new(init_a.width(), init_a.height());
for (x, y, value) in result.iter_mut() {
*value = dist_a.get(x, y).unwrap()
- dist_inv_a.get(x, y).unwrap()
+ if *init_a.get(x, y).unwrap() {1.} else {0.}
- 0.5;
}
result
};
phi
}
fn get_curvature(phi: &FloatGrid, idx: &Vec<(usize,usize)>) -> Vec<f64> {
let (phi_x, phi_y, phi_xx, phi_yy, phi_xy) = {
let (mut res_x, mut res_y, mut res_xx, mut res_yy, mut res_xy)
: (Vec<f64>, Vec<f64>, Vec<f64>, Vec<f64>, Vec<f64>) = (
Vec::with_capacity(idx.len()),
Vec::with_capacity(idx.len()),
Vec::with_capacity(idx.len()),
Vec::with_capacity(idx.len()),
Vec::with_capacity(idx.len()));
for &(x, y) in idx.iter() {
let left = if x > 0 { x - 1 } else { 0 };
let right = if x < phi.width() - 1 { x + 1 } else { phi.width() - 1 };
let up = if y > 0 { y - 1 } else { 0 };
let down = if y < phi.height() - 1 { y + 1 } else { phi.height() - 1 };
res_x.push(-*phi.get(left, y).unwrap() + *phi.get(right, y).unwrap());
res_y.push(-*phi.get(x, down).unwrap() + *phi.get(x, up).unwrap());
res_xx.push(
*phi.get(left, y).unwrap()
- 2.0 * *phi.get(x, y).unwrap()
+ *phi.get(right, y).unwrap());
res_yy.push(
*phi.get(x, up).unwrap()
- 2.0 * *phi.get(x, y).unwrap()
+ *phi.get(x, down).unwrap());
res_xy.push(0.25*(
-*phi.get(left, down).unwrap() - *phi.get(right, up).unwrap()
+*phi.get(right, down).unwrap() + *phi.get(left, up).unwrap()
));
}
(res_x, res_y, res_xx, res_yy, res_xy)
};
let phi_x2: Vec<f64> = phi_x.iter().map(|x| x*x).collect();
let phi_y2: Vec<f64> = phi_y.iter().map(|x| x*x).collect();
let curvature: Vec<f64> = (0..idx.len()).map(|i| {
((phi_x2[i]*phi_yy[i] + phi_y2[i]*phi_xx[i] - 2.*phi_x[i]*phi_y[i]*phi_xy[i])/
(phi_x2[i] + phi_y2[i] + f64::EPSILON).powf(1.5))*(phi_x2[i] + phi_y2[i]).powf(0.5)
}).collect();
curvature
}
fn sussman(grid: &FloatGrid, dt: &f64) -> FloatGrid {
let (a, b, c, d) = {
let mut a_res = FloatGrid::new(grid.width(), grid.height());
let mut b_res = FloatGrid::new(grid.width(), grid.height());
let mut c_res = FloatGrid::new(grid.width(), grid.height());
let mut d_res = FloatGrid::new(grid.width(), grid.height());
for y in 0..grid.height() {
for x in 0..grid.width() {
a_res.set(x, y,
grid.get(x, y).unwrap()
- grid.get((x + grid.width() - 1) % grid.width(), y).unwrap());
b_res.set(x, y,
grid.get((x + 1) % grid.width(), y).unwrap()
- grid.get(x, y).unwrap());
c_res.set(x, y,
grid.get(x, y).unwrap()
- grid.get(x, (y + 1) % grid.height()).unwrap());
d_res.set(x, y,
grid.get(x, (y + grid.height() - 1) % grid.height()).unwrap()
- grid.get(x, y).unwrap());
}
}
(a_res, b_res, c_res, d_res)
};
let (a_p, a_n, b_p, b_n, c_p, c_n, d_p, d_n) = {
let mut a_p_res = FloatGrid::new(grid.width(), grid.height());
let mut a_n_res = FloatGrid::new(grid.width(), grid.height());
let mut b_p_res = FloatGrid::new(grid.width(), grid.height());
let mut b_n_res = FloatGrid::new(grid.width(), grid.height());
let mut c_p_res = FloatGrid::new(grid.width(), grid.height());
let mut c_n_res = FloatGrid::new(grid.width(), grid.height());
let mut d_p_res = FloatGrid::new(grid.width(), grid.height());
let mut d_n_res = FloatGrid::new(grid.width(), grid.height());
for y in 0..grid.height() {
for x in 0..grid.width() {
let a_p_dval = *a.get(x, y).unwrap();
let a_n_dval = *a.get(x, y).unwrap();
let b_p_dval = *b.get(x, y).unwrap();
let b_n_dval = *b.get(x, y).unwrap();
let c_p_dval = *c.get(x, y).unwrap();
let c_n_dval = *c.get(x, y).unwrap();
let d_p_dval = *d.get(x, y).unwrap();
let d_n_dval = *d.get(x, y).unwrap();
a_p_res.set(x, y, if a_p_dval >= 0.0 { a_p_dval } else { 0.0 });
a_n_res.set(x, y, if a_n_dval <= 0.0 { a_n_dval } else { 0.0 });
b_p_res.set(x, y, if b_p_dval >= 0.0 { b_p_dval } else { 0.0 });
b_n_res.set(x, y, if b_n_dval <= 0.0 { b_n_dval } else { 0.0 });
c_p_res.set(x, y, if c_p_dval >= 0.0 { c_p_dval } else { 0.0 });
c_n_res.set(x, y, if c_n_dval <= 0.0 { c_n_dval } else { 0.0 });
d_p_res.set(x, y, if d_p_dval >= 0.0 { d_p_dval } else { 0.0 });
d_n_res.set(x, y, if d_n_dval <= 0.0 { d_n_dval } else { 0.0 });
}
}
(a_p_res, a_n_res, b_p_res, b_n_res, c_p_res, c_n_res, d_p_res, d_n_res)
};
let mut d_d = FloatGrid::new(grid.width(), grid.height());
let (d_neg_ind, d_pos_ind) = {
let mut res = (Vec::new(), Vec::new());
for (x, y, &value) in grid.iter() {
if value < 0.0 {
res.0.push((x, y));
}
else if value > 0.0 {
res.1.push((x,y));
}
}
res
};
for index in d_pos_ind {
let mut ap = *a_p.get(index.0, index.1).unwrap();
let mut bn = *b_n.get(index.0, index.1).unwrap();
let mut cp = *c_p.get(index.0, index.1).unwrap();
let mut dn = *d_n.get(index.0, index.1).unwrap();
ap *= ap;
bn *= bn;
cp *= cp;
dn *= dn;
d_d.set(index.0, index.1, (ap.max(bn) + cp.max(dn)).sqrt() - 1.);
}
for index in d_neg_ind {
let mut an = *a_n.get(index.0, index.1).unwrap();
let mut bp = *b_p.get(index.0, index.1).unwrap();
let mut cn = *c_n.get(index.0, index.1).unwrap();
let mut dp = *d_p.get(index.0, index.1).unwrap();
an *= an;
bp *= bp;
cn *= cn;
dp *= dp;
d_d.set(index.0, index.1, (an.max(bp) + cn.max(dp)).sqrt() - 1.);
}
let ss_d = sussman_sign(&grid);
let mut res = FloatGrid::new(grid.width(), grid.height());
for (x, y, value) in res.iter_mut() {
let dval = grid.get(x, y).unwrap();
let ss_dval = ss_d.get(x, y).unwrap();
let d_dval = d_d.get(x, y).unwrap();
*value = dval - dt*ss_dval*d_dval;
}
res
}
fn sussman_sign(d: &FloatGrid) -> FloatGrid {
let mut res = FloatGrid::new(d.width(), d.height());
for (x, y, value) in res.iter_mut() {
let v = d.get(x, y).unwrap();
*value = v/(v*v + 1.).sqrt();
}
res
}
fn convergence(p_mask: &BoolGrid,
n_mask: &BoolGrid,
thresh: u32,
c: u32) -> u32 {
let n_diff = p_mask.iter().zip(n_mask.iter()).fold(0u32, |acc, ((_,_,p),(_,_,n))| {
acc + if *p == *n { 1 } else { 0 }
});
if n_diff < thresh {
c + 1
}
else {
0
}
}