Repair photosites beyond 8 sigma of every neighbour before the network

The app's hot-pixel pass takes gross defects only; at ISO 6400-25600 a 6D
frame keeps 1000-2000 photosites more than 8 sigma beyond all their
same-colour and adjacent neighbours, which the network turned into specks.
The same two tests with the threshold in the photosite's own sigma, plus
the factor of two that keeps a bright point of light (where 8 sigma is a
sliver of the signal). The next model is trained behind exactly this; on
an ISO 25600 frame the Rust and training code both repair 935.

core/dr-denoise/src/lib.rs

@@ -19,6 +19,7 @@
 pub mod noise;
 #[cfg(feature = "onnx")]
 pub mod onnx;
+pub mod repair;
 pub mod tile;
 
 use dr_decode::RawImage;
@@ -67,12 +68,23 @@ pub fn denoise(
     }
     let active = noise::active(raw);
     let (h, w) = (active.h, active.w);
+    // The active area laid out once, then the noise-aware repair the model
+    // was trained behind (see `repair`).
+    let mut mosaic: Vec<f32> = (0..h * w).map(|i| active.at(i / w, i % w)).collect();
+    let pattern = raw.cfa_pattern;
+    let repaired = repair::repair(&mut mosaic, h, w, repair::REPAIR_K, &|y, x, v| {
+        noise.sigma(pattern.colour_at(x as u32, y as u32) as usize, v)
+    });
+    log::info!(
+        "learned denoise: {repaired} photosites beyond {}σ of every neighbour repaired",
+        repair::REPAIR_K
+    );
     tile::run_tiled(
         net,
         h,
         w,
         raw.cfa_pattern,
-        &|y, x| active.at(y, x),
+        &|y, x| mosaic[y * w + x],
         &|c, v| noise.sigma(c, v),
         progress,
     )