- all tests passing

src/register.rs

@@ -64,6 +64,7 @@ impl RegistrationStep {
     /// **NOT downsampled**. See: `itkMultiResolutionGaussianSmoothingPyramidImageFilter.hxx`
     ///
     /// Schedule [8, 4, 2, 1] means σ = [4.0, 2.0, 1.0, 0.5] (spacing=1).
+    /// MaximumNumberOfIterations: 256 (matching SimpleElastix default affine).
     pub fn default_steps(ndim: usize, n: usize) -> Vec<Self> {
         let sigma_schedule: Vec<f64> = vec![4.0, 2.0, 1.0, 0.5];
         let nlevels = sigma_schedule.len();
@@ -81,7 +82,7 @@ impl RegistrationStep {
                 32,
                 1e-6,
                 0.05,
-                512,
+                256,
                 1.0,
             ));
         }
@@ -309,7 +310,7 @@ impl<D: Dimension> Registration<D> {
                 continue;
             }
             let bf = BSpline::<0, _>::new(f.view());
-            let bm = BSpline::<3, _>::new(m.view());
+            let bm = BSpline::<1, _>::new(m.view());
             let metric = MattesMetric::new(bf, bm, samples, n_bins, edge)?
                 .with_fixed_mu(self.fixed_mu.clone());
 
@@ -409,7 +410,7 @@ impl<D: Dimension> Registration<D> {
             }
 
             let bf = BSpline::<0, _>::new(f.view());
-            let bm = BSpline::<3, _>::new(m.view());
+            let bm = BSpline::<1, _>::new(m.view());
             let n_samples = match &samples {
                 SamplingArg::Fixed(n) => *n,
                 SamplingArg::Random(n) => *n,