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lightcraft/crates/raw/src/dngwrite.rs
T
Brandon ThomasandClaude Opus 5.5 543fdde41e M13.1: lightcraft-merge crate — HDR merge, panorama stitching core
New L3 crate `crates/merge` (no UI deps), clean-room from published papers:
- features: Harris/MOPS-style oriented patch descriptors, ANMS, ratio-test matching
- ransac: normalised DLT homographies, similarity/translation, adaptive RANSAC
- hdr: brightness ordering, auto-align (model selection), robust exposure-ratio
  estimation chained to the reference, saturation-aware weighted radiance merge,
  deghost None/Low/Medium/High with feathered masks + overlay
- pano: pairwise matching, Brown–Lowe verification, focal from homographies,
  rotation+focal bundle adjustment (LM), straightening, spherical/cylindrical/
  perspective + auto, gain compensation, max-weight seams, multi-band blending
  in log space, boundary warp, auto crop, fill edges (push–pull)
- output: LinearRaw DNG carrying source colour tags; raw crate gains Deflate
  tiles (16/32-bit float with FP predictor, 16-bit int with predictor 2)

Tests: synthetic brackets (alignment < 0.3 px, EV < 0.02, radiance error
noise-limited, ghost removal) and synthetic panoramas (relative rotations
< 0.1°, focal < 1 %, error vs ground truth, seam test).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-01 10:06:00 -04:00

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Rust
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//! Writing DNG files from a [`RawImage`] (uncompressed or lossless-JPEG tiles), used for DNG export and for
//! bit-exact decoder round-trip tests. The raw image is stored in IFD0 (allowed by DNG 1.7 §"File Structure").
use crate::{RawData, RawError, RawImage, Result, ljpeg, opcodes};
use lightcraft_color::Mat3;
use lightcraft_tiff::tags::{self as t, compression, photometric};
use lightcraft_tiff::writer::{rational, srational};
use lightcraft_tiff::{ByteOrder, IfdBuilder, ImageData, TiffWriter, Value};
use rayon::prelude::*;
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum DngCompression {
Uncompressed,
/// Lossless JPEG tiles of `tile × tile` pixels (`tile` even). CFA tiles are encoded as two interleaved
/// components of half the tile width (the common DNG layout), linear data with one component per sample.
Lj92 {
tile: u32,
},
/// Deflate (zlib) tiles of `tile × tile` pixels. Floating-point data is stored as 16-bit (`half`) or
/// 32-bit IEEE floats with the floating-point predictor (TIFF predictor 3, Adobe TIFF Technical Note 3);
/// integer data with horizontal differencing (predictor 2). 16-bit float is what HDR merges usually use.
Deflate {
tile: u32,
half: bool,
},
}
/// IEEE 754 binary32 → binary16 (round to nearest even; overflow → ±inf, NaN kept).
pub fn f32_to_f16(v: f32) -> u16 {
let b = v.to_bits();
let sign = ((b >> 16) & 0x8000) as u16;
let exp = ((b >> 23) & 0xff) as i32;
let man = b & 0x7f_ffff;
if exp == 0xff {
return sign | 0x7c00 | if man != 0 { 0x200 } else { 0 };
}
let e = exp - 127 + 15;
if e >= 0x1f {
return sign | 0x7c00;
}
if e <= 0 {
if e < -10 {
return sign;
}
// subnormal half
let m = man | 0x80_0000;
let shift = (14 - e) as u32;
let half = m >> shift;
let rem = m & ((1 << shift) - 1);
let mid = 1 << (shift - 1);
let r = if rem > mid || (rem == mid && half & 1 == 1) { half + 1 } else { half };
return sign | r as u16;
}
let half = ((e as u32) << 10) | (man >> 13);
let rem = man & 0x1fff;
let r = if rem > 0x1000 || (rem == 0x1000 && half & 1 == 1) { half + 1 } else { half };
sign | r as u16
}
/// Apply the floating-point predictor (inverse of `unpack::undo_float_predictor`) to one row of
/// `n` big-endian samples of `bytes_per` bytes: split into byte planes (most significant first), then
/// byte-difference with `stride` samples.
fn float_predict(row: &[u8], n: usize, bytes_per: usize, stride: usize) -> Vec<u8> {
let mut planes = vec![0u8; row.len()];
for i in 0..n {
for b in 0..bytes_per {
planes[b * n + i] = row[i * bytes_per + b];
}
}
for i in (stride..planes.len()).rev() {
planes[i] = planes[i].wrapping_sub(planes[i - stride]);
}
planes
}
#[derive(Clone, Debug, PartialEq)]
pub struct DngWriteOptions {
pub compression: DngCompression,
pub order: ByteOrder,
/// XMP packet to embed (tag 700); defaults to one generated from the image metadata.
pub xmp: Option<String>,
}
impl Default for DngWriteOptions {
fn default() -> Self {
Self { compression: DngCompression::Lj92 { tile: 256 }, order: ByteOrder::Little, xmp: None }
}
}
fn srat_mat(m: &Mat3) -> Value {
Value::SRational(m.0.iter().flatten().map(|&v| srational(v)).collect())
}
fn rat_vec(v: &[f64]) -> Value {
Value::Rational(v.iter().map(|&x| rational(x)).collect())
}
/// Serialise `raw` as a DNG.
pub fn write_dng(raw: &RawImage, opts: &DngWriteOptions) -> Result<Vec<u8>> {
raw.validate()?;
let (w, h, cpp) = (raw.width, raw.height, raw.cpp);
let mut ifd = IfdBuilder::new();
ifd.set(t::NEW_SUBFILE_TYPE, Value::Long(vec![0]));
ifd.set(t::IMAGE_WIDTH, Value::Long(vec![w as u32]));
ifd.set(t::IMAGE_LENGTH, Value::Long(vec![h as u32]));
ifd.set(t::SAMPLES_PER_PIXEL, Value::Short(vec![cpp as u16]));
ifd.set(t::PLANAR_CONFIGURATION, Value::Short(vec![1]));
ifd.set(t::PHOTOMETRIC, Value::Short(vec![if raw.cfa.is_some() { photometric::CFA } else { photometric::LINEAR_RAW }]));
ifd.set(t::DNG_VERSION, Value::Byte(vec![1, 4, 0, 0]));
ifd.set(t::DNG_BACKWARD_VERSION, Value::Byte(vec![1, 3, 0, 0]));
let make = raw.metadata.make.clone().unwrap_or_default();
let model = raw.metadata.model.clone().unwrap_or_default();
if !make.is_empty() {
ifd.set(t::MAKE, Value::Ascii(make.clone()));
}
if !model.is_empty() {
ifd.set(t::MODEL, Value::Ascii(model.clone()));
}
let unique = format!("{make} {model}").trim().to_string();
ifd.set(t::UNIQUE_CAMERA_MODEL, Value::Ascii(if unique.is_empty() { "LightCraft".into() } else { unique }));
ifd.set(t::ORIENTATION, Value::Short(vec![raw.orientation.to_exif()]));
ifd.set(t::SOFTWARE, Value::Ascii("LightCraft".into()));
let xmp = opts.xmp.clone().unwrap_or_else(|| lightcraft_meta::write_xmp(&raw.metadata, None));
ifd.set(t::XMP, Value::Byte(xmp.into_bytes()));
if let Some(cfa) = &raw.cfa {
ifd.set(t::CFA_REPEAT_PATTERN_DIM, Value::Short(vec![cfa.height as u16, cfa.width as u16]));
ifd.set(t::CFA_PATTERN_EP, Value::Byte(cfa.pattern.clone()));
ifd.set(t::CFA_PLANE_COLOR, Value::Byte(vec![0, 1, 2]));
ifd.set(t::CFA_LAYOUT, Value::Short(vec![1]));
}
let b = &raw.black;
ifd.set(t::BLACK_LEVEL_REPEAT_DIM, Value::Short(vec![b.repeat_rows as u16, b.repeat_cols as u16]));
let mut bl: Vec<f64> = b.values.iter().map(|&v| v as f64).collect();
if bl.len() == 1 && cpp > 1 {
bl = vec![bl[0]; cpp];
}
ifd.set(t::BLACK_LEVEL, rat_vec(&bl));
if !b.delta_h.is_empty() {
ifd.set(t::BLACK_LEVEL_DELTA_H, Value::SRational(b.delta_h.iter().map(|&v| srational(v as f64)).collect()));
}
if !b.delta_v.is_empty() {
ifd.set(t::BLACK_LEVEL_DELTA_V, Value::SRational(b.delta_v.iter().map(|&v| srational(v as f64)).collect()));
}
let white: Vec<u32> = (0..cpp).map(|s| raw.white_at(s).round().clamp(0.0, u32::MAX as f32) as u32).collect();
if matches!(raw.data, RawData::F32(_)) {
ifd.set(t::WHITE_LEVEL, rat_vec(&(0..cpp).map(|s| raw.white_at(s) as f64).collect::<Vec<_>>()));
} else {
ifd.set(t::WHITE_LEVEL, Value::Long(white));
}
let a = raw.active_area;
ifd.set(t::ACTIVE_AREA, Value::Long(vec![a.y as u32, a.x as u32, (a.y + a.height) as u32, (a.x + a.width) as u32]));
ifd.set(t::DEFAULT_CROP_ORIGIN, Value::Long(vec![raw.crop.x as u32, raw.crop.y as u32]));
ifd.set(t::DEFAULT_CROP_SIZE, Value::Long(vec![raw.crop.width as u32, raw.crop.height as u32]));
let c = &raw.color;
for (i, tag) in [t::CALIBRATION_ILLUMINANT_1, t::CALIBRATION_ILLUMINANT_2].into_iter().enumerate() {
if c.color_matrix[i].is_some() {
ifd.set(tag, Value::Short(vec![c.illuminant[i]]));
}
}
for (pair, tags) in [
(&c.color_matrix, [t::COLOR_MATRIX_1, t::COLOR_MATRIX_2]),
(&c.forward_matrix, [t::FORWARD_MATRIX_1, t::FORWARD_MATRIX_2]),
(&c.camera_calibration, [t::CAMERA_CALIBRATION_1, t::CAMERA_CALIBRATION_2]),
] {
for i in 0..2 {
if let Some(m) = &pair[i] {
ifd.set(tags[i], srat_mat(m));
}
}
}
if let Some(v) = c.analog_balance {
ifd.set(t::ANALOG_BALANCE, rat_vec(&v));
}
if let Some(v) = c.as_shot_neutral {
ifd.set(t::AS_SHOT_NEUTRAL, rat_vec(&v));
} else if let Some(xy) = c.as_shot_white_xy {
ifd.set(t::AS_SHOT_WHITE_XY, rat_vec(&[xy.x, xy.y]));
}
ifd.set(t::BASELINE_EXPOSURE, Value::SRational(vec![srational(c.baseline_exposure)]));
for (list, tag) in [(&raw.opcodes.list1, t::OPCODE_LIST_1), (&raw.opcodes.list2, t::OPCODE_LIST_2), (&raw.opcodes.list3, t::OPCODE_LIST_3)] {
if !list.is_empty() {
ifd.set(tag, Value::Undefined(opcodes::write_list(list)));
}
}
match &raw.data {
RawData::F32(v) if matches!(opts.compression, DngCompression::Deflate { .. }) => {
let DngCompression::Deflate { tile, half } = opts.compression else { unreachable!() };
let tile = (tile.max(16) & !15) as usize;
let bp = if half { 2 } else { 4 };
ifd.set(t::BITS_PER_SAMPLE, Value::Short(vec![(bp * 8) as u16; cpp]));
ifd.set(t::SAMPLE_FORMAT, Value::Short(vec![3; cpp]));
ifd.set(t::COMPRESSION, Value::Short(vec![compression::ADOBE_DEFLATE]));
ifd.set(t::PREDICTOR, Value::Short(vec![3]));
let (ta, td) = (w.div_ceil(tile), h.div_ceil(tile));
let tiles: Vec<Vec<u8>> = (0..ta * td)
.into_par_iter()
.map(|i| {
let (tx, ty) = (i % ta * tile, i / ta * tile);
let mut buf = Vec::with_capacity(tile * tile * cpp * bp);
let mut row = Vec::with_capacity(tile * cpp * bp);
for y in 0..tile {
let sy = (ty + y).min(h - 1);
row.clear();
for x in 0..tile {
let sx = (tx + x).min(w - 1);
for s in 0..cpp {
let f = v[(sy * w + sx) * cpp + s];
if half {
row.extend_from_slice(&f32_to_f16(f).to_be_bytes());
} else {
row.extend_from_slice(&f.to_bits().to_be_bytes());
}
}
}
buf.extend_from_slice(&float_predict(&row, tile * cpp, bp, cpp));
}
miniz_oxide::deflate::compress_to_vec_zlib(&buf, 6)
})
.collect();
ifd.set_image(ImageData::Tiles { tile_width: tile as u32, tile_height: tile as u32, tiles });
}
RawData::F32(v) => {
ifd.set(t::BITS_PER_SAMPLE, Value::Short(vec![32; cpp]));
ifd.set(t::SAMPLE_FORMAT, Value::Short(vec![3; cpp]));
ifd.set(t::COMPRESSION, Value::Short(vec![compression::NONE]));
let mut bytes = Vec::with_capacity(v.len() * 4);
for &x in v {
let mut tmp = Vec::with_capacity(4);
opts.order.put_u32(&mut tmp, x.to_bits());
bytes.extend_from_slice(&tmp);
}
ifd.set_image(ImageData::Strips { rows_per_strip: h as u32, strips: vec![bytes] });
}
RawData::U16(v) => {
let maxv = v.iter().copied().max().unwrap_or(0);
let bits = (16 - maxv.leading_zeros()).max(raw.bits.min(16)).max(2) as u8;
ifd.set(
t::BITS_PER_SAMPLE,
Value::Short(vec![if matches!(opts.compression, DngCompression::Uncompressed) { 16 } else { bits as u16 }; cpp]),
);
match opts.compression {
DngCompression::Uncompressed => {
ifd.set(t::COMPRESSION, Value::Short(vec![compression::NONE]));
let rows = (65536 / (w * cpp * 2)).clamp(1, h);
let strips = v
.chunks(rows * w * cpp)
.map(|s| {
let mut b = Vec::with_capacity(s.len() * 2);
s.iter().for_each(|&x| opts.order.put_u16(&mut b, x));
b
})
.collect();
ifd.set_image(ImageData::Strips { rows_per_strip: rows as u32, strips });
}
DngCompression::Deflate { tile, .. } => {
let tile = (tile.max(16) & !15) as usize;
ifd.set(t::BITS_PER_SAMPLE, Value::Short(vec![16; cpp]));
ifd.set(t::COMPRESSION, Value::Short(vec![compression::ADOBE_DEFLATE]));
ifd.set(t::PREDICTOR, Value::Short(vec![2]));
let (ta, td) = (w.div_ceil(tile), h.div_ceil(tile));
let tiles: Vec<Vec<u8>> = (0..ta * td)
.into_par_iter()
.map(|i| {
let (tx, ty) = (i % ta * tile, i / ta * tile);
let mut buf = Vec::with_capacity(tile * tile * cpp * 2);
let mut row = vec![0u16; tile * cpp];
for y in 0..tile {
let sy = (ty + y).min(h - 1);
for x in 0..tile {
let sx = (tx + x).min(w - 1);
for s in 0..cpp {
row[x * cpp + s] = v[(sy * w + sx) * cpp + s];
}
}
for i in (cpp..row.len()).rev() {
row[i] = row[i].wrapping_sub(row[i - cpp]);
}
row.iter().for_each(|&x| opts.order.put_u16(&mut buf, x));
}
miniz_oxide::deflate::compress_to_vec_zlib(&buf, 6)
})
.collect();
ifd.set_image(ImageData::Tiles { tile_width: tile as u32, tile_height: tile as u32, tiles });
}
DngCompression::Lj92 { tile } => {
let tile = (tile.max(2) & !1) as usize;
if tile > 65534 {
return Err(RawError::Limit("tile too large"));
}
ifd.set(t::COMPRESSION, Value::Short(vec![compression::JPEG]));
let (ta, td) = (w.div_ceil(tile), h.div_ceil(tile));
let tiles: Vec<Vec<u8>> = (0..ta * td)
.into_par_iter()
.map(|i| {
let (tx, ty) = (i % ta * tile, i / ta * tile);
let mut buf = Vec::with_capacity(tile * tile * cpp);
for y in 0..tile {
let sy = (ty + y).min(h - 1);
for x in 0..tile {
let sx = (tx + x).min(w - 1);
for s in 0..cpp {
buf.push(v[(sy * w + sx) * cpp + s]);
}
}
}
if cpp == 1 {
ljpeg::encode(&buf, tile / 2, tile, 2, bits, 1, 0)
} else {
ljpeg::encode(&buf, tile, tile, cpp, bits, 1, 0)
}
})
.collect();
ifd.set_image(ImageData::Tiles { tile_width: tile as u32, tile_height: tile as u32, tiles });
}
}
}
}
Ok(TiffWriter::new(opts.order, false).write(&[ifd])?)
}