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DarkRoom/core/dr-denoise/src/noise.rs
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dtourolle dd43f498fb Run the learned denoise in develop, and export with it
A Bayer photograph keeps its mosaic in the session and is offered the AI
Denoise switch. Asked for, the network runs on the decode executor from a
hot-pixel-repaired copy — the app's own pass — with the frame's noise from
its best source, and its progress in the activity bar; the classical
demosaic shows until the result lands, and the finished job says where the
noise figures came from. Keep grain is a GrainBlend of the two, made once
per value; the render draws it as its source and the adjust pass never
knows. demosaiced stays the classical result, so the raw histogram, the
white balance picker, masks and segmentation still read the sensor.

The develop view reconciles on a 250 ms poll rather than on each way an
edit can change (slider, undo, preset, version, a sidecar from another
device): two comparisons when nothing changed, and no path that can forget.
A failure is not retried until the switch is toggled. An export of a
photograph that asks for it waits for a running job or computes it.
2026-10-03 11:51:00 -04:00

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//! TRACES: FR-DEV-3g
//! How noisy each photosite is: the network is told, not left to guess
//! (denoise.md §3.3).
//!
//! The model is `σ² = S·x + O + row² + col²` per photosite, `x` the signal
//! normalised black-to-white the way the demosaic normalises it. Three
//! sources, best first:
//!
//! 1. **A measured table** for the body ([`Source::Table`]) — the Canon EOS 6D
//! today, from the library's own frames.
//! 2. **The DNG's `NoiseProfile`** ([`Source::DngProfile`]) — what Adobe's
//! converter measured for the body at that ISO.
//! 3. **The frame itself** ([`Source::Measured`]) — read, row and column
//! noise from its masked border, which is a dark frame taken in the same
//! instant, and only the shot gain estimated, from the quietest flat
//! patches. Checked against the 6D's table on 130 frames: within ±10 % at
//! ISO 1000 and above, scattered below; the network loses under 0.3 dB for
//! a σ off by 15–20 %, and over-estimating costs half what
//! under-estimating does, so the estimate leans high.
//!
//! Row and column noise come from the masked border whenever the frame has
//! one, whatever the source of the rest.
use dr_decode::{CfaPattern, RawImage};
use serde::Deserialize;
/// Where a frame's noise figures came from, for develop to say.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Source {
Table,
DngProfile,
Measured,
}
impl Source {
pub fn label(self) -> &'static str {
match self {
Source::Table => "measured for this camera",
Source::DngProfile => "from the DNG's noise profile",
Source::Measured => "estimated from this photograph",
}
}
}
/// Per-photosite noise in the frame's own normalisation (black 0, white 1).
#[derive(Clone, Debug, PartialEq)]
pub struct NoiseModel {
/// Shot gain per colour, R G B.
pub s: [f32; 3],
/// Read variance per colour, R G B.
pub o: [f32; 3],
/// Standard deviation shared by a whole row, and by a whole column.
pub row: f32,
pub col: f32,
pub source: Source,
}
impl NoiseModel {
/// σ for a photosite of colour `c` (0 R, 1 G, 2 B) reading `x`.
#[inline]
pub fn sigma(&self, c: usize, x: f32) -> f32 {
(self.s[c] * x.max(0.0) + self.o[c] + self.row * self.row + self.col * self.col).sqrt()
}
/// The same figures scaled for the Amount the spec describes (§3.3):
/// above 1 tells the network there is more noise than there is.
pub fn scaled(&self, amount: f32) -> NoiseModel {
let a2 = amount * amount;
NoiseModel {
s: self.s.map(|v| v * a2),
o: self.o.map(|v| v * a2),
row: self.row * amount,
col: self.col * amount,
source: self.source,
}
}
}
/// The frame's noise, from the best source it has.
///
/// `bytes` is the file (for a DNG's `NoiseProfile`), `iso` its EXIF ISO.
/// `None` only for a frame with no masked border, no profile and no table
/// that is also too dark or too busy to measure.
pub fn for_frame(raw: &RawImage, bytes: &[u8], iso: Option<u32>) -> Option<NoiseModel> {
for_frame_with(raw, dr_decode::noise_profile(bytes).as_deref(), iso)
}
/// [`for_frame`], given the file's `NoiseProfile` already read
/// ([`dr_decode::noise_profile`]) rather than the file, for a caller that
/// keeps the header's answer and not the bytes.
pub fn for_frame_with(
raw: &RawImage,
profile: Option<&[(f32, f32)]>,
iso: Option<u32>,
) -> Option<NoiseModel> {
let dark = dark_border(raw);
let mut model = iso
.and_then(|iso| from_table(raw, iso))
.or_else(|| profile.and_then(|p| from_dng_profile(raw, p)))
.or_else(|| measured(raw, dark.as_ref()))?;
if let Some(d) = dark {
// The border saw this exposure's row and column noise directly.
if model.source != Source::Table {
model.row = d.row;
model.col = d.col;
}
}
Some(model)
}
#[derive(Deserialize)]
struct Table {
make: String,
model: String,
rows: Vec<TableRow>,
}
#[derive(Deserialize)]
struct TableRow {
iso: u32,
s_dn: [f32; 4],
o_dn: [f32; 4],
row_dn: f32,
col_dn: f32,
}
const TABLES: &[&str] = &[include_str!("../tables/canon-eos-6d.yaml")];
/// The body's measured table at the nearest ISO it holds, converted from DN
/// to this frame's normalisation.
pub fn from_table(raw: &RawImage, iso: u32) -> Option<NoiseModel> {
let table = TABLES.iter().find_map(|t| {
let t: Table = serde_norway::from_str(t).ok()?;
(t.make.eq_ignore_ascii_case(&raw.make) && t.model.eq_ignore_ascii_case(&raw.model))
.then_some(t)
})?;
let row = table.rows.iter().min_by(|a, b| {
let d = |r: &TableRow| ((r.iso as f32).ln() - (iso as f32).ln()).abs();
d(a).total_cmp(&d(b))
})?;
let span = span(raw);
// RGGB positions → colours: the greens share.
let s = [row.s_dn[0], 0.5 * (row.s_dn[1] + row.s_dn[2]), row.s_dn[3]].map(|v| v / span);
let o =
[row.o_dn[0], 0.5 * (row.o_dn[1] + row.o_dn[2]), row.o_dn[3]].map(|v| v / (span * span));
Some(NoiseModel {
s,
o,
row: row.row_dn / span,
col: row.col_dn / span,
source: Source::Table,
})
}
/// A DNG's `NoiseProfile`: one pair for every plane, or one per colour plane
/// (R, G, B for a Bayer DNG), already in the file's black-to-white units —
/// which are the units `dr-decode` normalises by.
pub fn from_dng_profile(raw: &RawImage, pairs: &[(f32, f32)]) -> Option<NoiseModel> {
if raw.cfa_pattern.is_xtrans() || raw.samples_per_pixel != 1 {
return None;
}
let (s, o) = match pairs {
[(s, o)] => ([*s; 3], [*o; 3]),
[r, g, b, ..] => ([r.0, g.0, b.0], [r.1, g.1, b.1]),
_ => return None,
};
Some(NoiseModel {
s,
o,
row: 0.0,
col: 0.0,
source: Source::DngProfile,
})
}
/// Read, row and column noise measured on the masked border, normalised.
#[derive(Clone, Copy, Debug)]
pub struct Dark {
pub read: f32,
pub row: f32,
pub col: f32,
}
/// The optically black photosites beside and above the active area.
///
/// Keeps well clear of the active area: on the 6D the dozen columns nearest
/// it see light. Photosites over 8σ are the strip's own hot photosites — the
/// same ones in every frame — and are left out, as the app's hot-pixel pass
/// removes their kin before the network sees them.
pub fn dark_border(raw: &RawImage) -> Option<Dark> {
let (x0, y0, w, h) = (
raw.crop.x as usize,
raw.crop.y as usize,
raw.crop.width as usize,
raw.crop.height as usize,
);
let stride = raw.width as usize;
let span = span(raw);
if x0 < 40 || raw.samples_per_pixel != 1 {
return None;
}
let cols = 4..x0 - 16;
let nc = cols.len() as f32;
// Residual after removing each row's mean and each column's mean.
let mut row_means = Vec::with_capacity(h);
let mut col_sum = vec![0.0f64; cols.len()];
for y in y0..y0 + h {
let line = &raw.data[y * stride..y * stride + x0];
let m = cols.clone().map(|x| line[x] as f32).sum::<f32>() / nc;
row_means.push(m);
for (k, x) in cols.clone().enumerate() {
col_sum[k] += (line[x] as f32 - m) as f64;
}
}
let col_mean: Vec<f32> = col_sum.iter().map(|s| (*s / h as f64) as f32).collect();
let resid = |y: usize, k: usize, x: usize| {
raw.data[y * stride + x] as f32 - row_means[y - y0] - col_mean[k]
};
let (mut s1, mut n) = (0.0f64, 0usize);
for y in y0..y0 + h {
for (k, x) in cols.clone().enumerate() {
s1 += (resid(y, k, x) as f64).powi(2);
n += 1;
}
}
let rough = (s1 / n as f64).sqrt() as f32;
let (mut s2, mut n2) = (0.0f64, 0usize);
for y in y0..y0 + h {
for (k, x) in cols.clone().enumerate() {
let r = resid(y, k, x);
if r.abs() < 8.0 * rough {
s2 += (r as f64).powi(2);
n2 += 1;
}
}
}
let read = (s2 / n2.max(1) as f64).sqrt() as f32;
let rm = row_means.iter().sum::<f32>() / h as f32;
let row_var = row_means.iter().map(|m| (m - rm).powi(2)).sum::<f32>() / h as f32;
let row = (row_var - read * read / nc).max(0.0).sqrt();
// Columns: the masked rows above the image span every column.
let col = if y0 >= 24 {
let rows = 4..y0 - 12;
let nr = rows.len() as f32;
let means: Vec<f32> = (x0..x0 + w)
.map(|x| {
rows.clone()
.map(|y| raw.data[y * stride + x] as f32)
.sum::<f32>()
/ nr
})
.collect();
let mm = means.iter().sum::<f32>() / means.len() as f32;
let var = means.iter().map(|m| (m - mm).powi(2)).sum::<f32>() / means.len() as f32;
(var - read * read / nr).max(0.0).sqrt()
} else {
0.0
};
Some(Dark {
read: read / span,
row: row / span,
col: col / span,
})
}
/// The quietest-third bias of the patch variance, and the residual bias the
/// estimate showed against the 6D's table (0.91 at the median), in one: the
/// estimate is divided by this.
const QUIET_FACTOR: f32 = 0.85 * 0.91;
/// The frame's own noise: read noise from the border (or, lacking one, the
/// floor of the quietest patches), shot gain from flat patches of one green
/// plane, the same for every colour, as a sensor's gain is.
pub fn measured(raw: &RawImage, dark: Option<&Dark>) -> Option<NoiseModel> {
if raw.cfa_pattern.is_xtrans() || raw.samples_per_pixel != 1 {
return None;
}
let m = active(raw);
let (h, w) = (m.h, m.w);
// One green plane at a two-photosite pitch.
let (gy, gx) = green_offset(raw.cfa_pattern)?;
let ph = (h - gy) / 2;
let pw = (w - gx) / 2;
let g = |y: usize, x: usize| m.at(gy + 2 * y, gx + 2 * x);
const B: usize = 8;
let mut patches: Vec<(f32, f32)> = Vec::new(); // (level, variance)
for by in 0..ph / B {
for bx in 0..(pw - 2) / B {
let (mut s, mut s2, mut lv) = (0.0f32, 0.0f32, 0.0f32);
for y in by * B..by * B + B {
for x in bx * B..bx * B + B {
// Second difference: cancels any gradient; var = 6σ².
let d = g(y, x + 2) - 2.0 * g(y, x + 1) + g(y, x);
s += d;
s2 += d * d;
lv += g(y, x + 1);
}
}
let n = (B * B) as f32;
let var = (s2 / n - (s / n).powi(2)) / 6.0;
patches.push((lv / n, var));
}
}
let floor = dark.map(|d| d.read);
let lo = 4.0 * floor.unwrap_or(0.002);
patches.retain(|(l, _)| *l > lo && *l < 0.7);
if patches.len() < 500 {
return None;
}
patches.sort_by(|a, b| a.0.total_cmp(&b.0));
let bins = 12;
let per = patches.len() / bins;
let mut ests = Vec::new();
let mut floors = Vec::new();
for b in 0..bins {
let mut bin: Vec<(f32, f32)> = patches[b * per..(b + 1) * per].to_vec();
if bin.len() < 60 {
continue;
}
bin.sort_by(|a, b| a.1.total_cmp(&b.1));
let quiet = &bin[..bin.len() / 3];
let read2 = floor.map(|r| r * r);
let mut e: Vec<f32> = quiet
.iter()
.map(|(l, v)| (v / QUIET_FACTOR - read2.unwrap_or(0.0)) / l)
.collect();
e.sort_by(f32::total_cmp);
ests.push(e[e.len() / 2]);
floors.push(quiet[quiet.len() / 2]);
}
ests.sort_by(f32::total_cmp);
let s = *ests.get(ests.len() / 2)?;
if !(s.is_finite() && s > 0.0) {
return None;
}
// No border: the read variance is what the darkest bin leaves unexplained.
let read2 = match floor {
Some(r) => r * r,
None => {
let (l, v) = floors.first().copied()?;
(v / QUIET_FACTOR - s * l).max(1e-9)
}
};
Some(NoiseModel {
s: [s; 3],
o: [read2; 3],
row: dark.map_or(0.0, |d| d.row),
col: dark.map_or(0.0, |d| d.col),
source: Source::Measured,
})
}
/// Black-to-white range of the frame, as the demosaic normalises it.
pub(crate) fn span(raw: &RawImage) -> f32 {
let black = raw.black_level.iter().map(|&b| b as f32).sum::<f32>() / 4.0;
(raw.white_level as f32 - black).max(1.0)
}
/// Where a green photosite sits in the pattern's 2×2 cell, (dy, dx).
fn green_offset(p: CfaPattern) -> Option<(usize, usize)> {
match p {
CfaPattern::Rggb | CfaPattern::Bggr => Some((0, 1)),
CfaPattern::Grbg | CfaPattern::Gbrg => Some((0, 0)),
_ => None,
}
}
/// The active area, normalised, read lazily.
pub(crate) struct Active<'a> {
raw: &'a RawImage,
black: [f32; 4],
inv: [f32; 4],
pub h: usize,
pub w: usize,
}
impl Active<'_> {
/// Photosite (y, x) of the active area, black 0, white 1.
#[inline]
pub fn at(&self, y: usize, x: usize) -> f32 {
let c = (y & 1) * 2 + (x & 1);
let v = self.raw.data[(self.raw.crop.y as usize + y) * self.raw.width as usize
+ self.raw.crop.x as usize
+ x];
(v as f32 - self.black[c]) * self.inv[c]
}
}
/// Black levels per position of the crop's 2×2 cell, as the demosaic reads
/// them: one reported level is broadcast.
pub(crate) fn active(raw: &RawImage) -> Active<'_> {
let b = raw.black_level;
let black = if b[1] == 0 && b[2] == 0 && b[3] == 0 {
[b[0] as f32; 4]
} else {
b.map(|v| v as f32)
};
let inv = black.map(|bl| 1.0 / (raw.white_level as f32 - bl).max(1.0));
Active {
raw,
black,
inv,
h: raw.crop.height as usize,
w: raw.crop.width as usize,
}
}