bbe77354e0
* Camera Raw: Whites, Blacks, Shadows and Highlights closer to Photoshop's Measured as a black box on Photoshop 25.4's Camera Raw Filter. Whites and Blacks are global curves of the grey level: the measured rows per slider value, Whites first, after Shadows and Highlights. The clipping directions adapt to the image's black and white points (Whites up to 2.7 times stronger on a dark image, Blacks at least 1.2). On ten public-domain photos the mean error against Photoshop drops from 4.2-36.8 to 0.9-8.9 levels of 255. Shadows and Highlights are a local Laplacian filter (Paris et al. 2011, fast form of Aubry et al. 2014) on the log luminance, the method Adobe credits for process version 2012. Shadows raises pixels darker than their surroundings by an amount set by their own and their surroundings' tone, so big edges keep no halo, and keeps the 99th percentile; Highlights pulls pixels brighter than their surroundings toward them and keeps the 1st. The strengths are fitted to the photos (mean error 2.8-9.4 levels, was 3.7-14.3); Photoshop's exact operator was not recovered. The tone stages decode light with the document's curve: filter.cameraRaw stores encodingGamma (1.8 for ProPhoto, where raws open). Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * Camera Raw Shadows/Highlights: no contour lines on smooth gradients Twelve reference values over a raw's whole range left more than a stop between them, and the remapping changes within half a stop: coefficients interpolated across that gap drew contour lines in out-of-focus areas (Shadows +100 on a Nikon D4 raw). References are now an eighth of a stop apart over the image's tones (the deepest 0.1 % share the lowest), on a copy at most 1600 px across whose change comes back to full size by a guided upsampling, so a 16-megapixel image takes about 2 s per slider and the preview matches the result. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * Camera Raw on raw opens: Shadows/Highlights in linear light, D4 look and black point as Photoshop Measured black-box on 29 Nikon D4 NEFs opened through Camera Raw in Photoshop 25.4 (sliders at +-100 and +50, exposure +-1) against our own linear development of the same files. - Shadows and Highlights of the open-time dialog now act while developing, in linear light before the tone curve, as Camera Raw does for raw files (exposure -1 gives the same gains). The log2 gain is slider/100 * C(B - anchor): B is a guided-filter base of the log2 luminance on a copy 1232 px on its long side, the anchor is image-adaptive (Shadows: log2 power mean p=1.5 of the linear luminance; Highlights: mean log2 luminance). New module photocraft_raw::tone; the preview undoes the camera curve to show the same (photocraft_raw::retone). - The D4 profile copies Camera Raw's default rendering: look matrix folded into the ForwardMatrix, per-channel curve, and an adaptive black point (0.33 x the 0.1th percentile of the luminance, Sensor::black_point). Against Photoshop on the 29 frames (1/4 size, log2 Y): default rendering median difference 0.29 -> 0.04 stop; correlation of the slider's effect Shadows +100 0.96, -100 0.91, Highlights -100 0.87, +100 0.85 (the previous filter model: 0.68 and 0.55 on DSG_3464). Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * docs: the open-time Camera Raw re-develop covers Shadows and Highlights Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * Camera Raw raw-stage Shadows: keep shadow contrast as Photoshop does The user saw Photoshop's shadows sink deeper with more contrast. Measured on the 29 D4 NEFs: with Shadows +100 our shadow detail had 0.79 of Photoshop's local contrast and shadows sat 0.38 stop lighter. Two causes: - The black point now comes before the Shadows / Highlights gain, as in Camera Raw (lifting first let the lift wash out the black point's deep-shadow contrast). - The guided upsampling's epsilon goes from 0.01 to 1 stop^2: the change follows strong edges but stays smooth inside texture (with 0.01 it followed every detail and flattened it). Near strong edges the effect still matches Photoshop as well as elsewhere. Shadows +100: shadow detail 0.79 -> 0.91, shadow bias +0.38 -> +0.16 stop; effect correlation Shadows -100 0.906 -> 0.946, Highlights -100 0.870 -> 0.886, others unchanged. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * Camera Raw on raw opens: Clarity, Texture and Dehaze in linear light, as Photoshop Measured black-box from Photoshop 25.4 opening 29 Nikon D4 NEFs through Camera Raw (descriptor keys Cl12, CrTx, Dhze; each at ±100 and +50, and +100 at exposure −1, 348 opens). All three act before the tone curve: the change at exposure −1 equals the one at 0 (correlation 0.98–0.99). - Clarity: log2 luminance split into bands between guided-filter bases (radii 2, 8, 32, 128 on the 1232 px work copy), each band scaled by a measured gain that follows its base's tone, plus a tone term; carried to full size with the Shadows / Highlights change. - Texture: Gaussian bands σ 0.5…16 on a half-size copy, each through its measured response (small detail raised more than strong edges, flat areas unchanged), guided-upsampled. - Dehaze: He, Sun and Tang's dark channel prior on linear ProPhoto (dark channel in Display P3, airlight from the brightest 0.1 % of it, guided-smoothed transmission), w 0.8 at +100; −100 a uniform veil. The black point stays the default rendering's. Against Photoshop, PhotoCraft's develop vs Photoshop's open on all 29 frames (median effect correlation, log2 luminance at 1/4 size, Texture at 1/2): Clarity +100 0.81, −100 0.85; Texture +100 0.85, −100 0.88; Dehaze +100 0.61 (0.78 in gamma 2.2: the crushed shadows differ), −100 0.96. Shadows / Highlights unchanged (0.964 / 0.886). The open-time Camera Raw dialog re-develops for them and its preview shows them (retone). Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Co-authored-by: Brandon Thomas <echelon@gmail.com>
12 KiB
photocraft-raw
A clean-room, pure-Rust camera raw decoder and developer. The crate is standalone (no workspace
dependencies; its decoding dependencies are flate2 for Deflate DNG and jxl-oxide, a pure-Rust
JPEG XL decoder, for DNG 1.7, native builds only), has no unsafe, does no I/O (&[u8] in), builds for wasm32-unknown-unknown
(sequential there, rayon-parallel on native) and never panics on hostile input: every offset is
bounds-checked and sizes are checked against Limits before allocating.
use photocraft_raw::{develop, DevelopOptions, Demosaic};
let dev = develop(&bytes, &DevelopOptions { demosaic: Demosaic::Ahd, ..Default::default() })?;
// dev.rgb: interleaved 16-bit RGB in ProPhoto RGB (ROMM primaries, D50, gamma 1.8)
// dev.warnings: anything approximated or not applied
photocraft-io uses it so opening a raw file yields a normal 16-bit RGB document tagged with the
built-in ProPhoto-compatible profile.
Sources (clean-room)
Implemented only from public specifications, papers and observation of files:
- TIFF 6.0, TIFF/EP (ISO 12234-2) and the Adobe DNG Specification 1.7.
- ITU-T T.81 (ISO 10918-1) Annex H: lossless JPEG, process 14 ("LJ92").
- The published description of Canon's CR2 container (header, raw IFD, slice tag 0xC640).
- Publicly documented maker-note / private tags (ExifTool's tag tables): Canon ModelID (0x0010), SensorInfo (0x00E0) and ColorData (0x4001), Nikon WB_RBLevels (0x000C) and BlackLevel (0x003D), Sony BlackLevel (0x7310), WB_RGGBLevels (0x7313), SonyRawFileType (0x7000) and SonyToneCurve (0x7010), the PanasonicRaw IFD0 tags, Olympus ImageProcessing (0x2040) and CameraSettings (0x2020) preview tags, the Fujifilm RAF header and metadata records (RawImageCropTopLeft / RawImageCroppedSize, FujiLayout, XTransLayout, WB_GRGBLevels, RawExposureBias) and FujiIFD (RawImageFullWidth / Height, BitsPerSample, StripOffsets / ByteCounts, BlackLevel, WB_GRBLevels).
- Nikon compressed NEF: Laurent Clévy's NEF structure notes and Bill Claff's "NEF Compression"
(prose: the
0x0096table layout, a lossy curve followed by a fixed-table Huffman stage), ExifTool's Nikon tag-name documentation and ITU-T T.81 Annex F / H. The Huffman tables are not stored in the files; they were recovered by black-box analysis of CC0 raw.pixls.us samples (the same scenes shot compressed and uncompressed) for LightCraft (storytold/lightcraft#86) and verified there on ~45 files from ~35 bodies. - Sony cRAW (ARW 2): H. Dietz, "Sony ARW2 Compression: Artifacts And Credible Repair" (Electronic Imaging 2016) and the RawDigger / diglloyd write-ups of the 11 + 7-bit scheme; the exact bit layout and tone-curve scale were established by observation of sample files.
- Panasonic RW2 RawFormat 5, uncompressed Olympus ORF and uncompressed Fujifilm RAF: established by observation of sample files (bit packing, page layout, sample justification; for RAF the three sample storages and the reversed order of the X-Trans / Bayer layout records, each verified by developing with every candidate phase against the camera's preview).
- Demosaicing: Malvar, He & Cutler (ICASSP 2004); Hirakawa & Parks, "Adaptive homogeneity-directed demosaicing" (IEEE TIP 2005); for X-Trans and other non-Bayer CFAs, gradient-weighted green interpolation (Lu & Tan, "Color filter array demosaicking: new method and performance measures", IEEE TIP 2003) with edge-aware colour differences.
- McCamy's CCT approximation (1992); the Bradford chromatic adaptation transform.
- Per-file colour from the camera's embedded JPEG (
fit_look,src/look.rs): the method follows the prose description in LightCraft'sdocs/camera-preview-colour.md(storytold/lightcraft#165, Apache-2.0, same organisation); no LightCraft code was used. Pool-adjacent-violators isotonic regression (Ayer et al., 1955), Tukey's biweight (Beaton & Tukey, 1974), ridge regression (Hoerl & Kennard, 1970) and the CIE 1976 L*a*b* colour difference.
No code from dcraw, LibRaw, rawspeed, rawler, rawloader or darktable was read or used, and no camera colour tables were copied.
Support matrix
| Format | Status |
|---|---|
| DNG | Uncompressed (8–16 bit, packed or not), Deflate (compression 8, predictors 1 and 2), lossless JPEG and JPEG XL (DNG 1.7, e.g. Samsung Expert RAW; decoded by jxl-oxide; not in wasm32 builds, where it is Unsupported); strips and tiles; CFA (Bayer) and LinearRaw (three-sample colour, or one-sample monochrome such as Leica Monochrom and film-scanner DNGs, developed as neutral grey with no white balance or colour matrix); LinearizationTable, BlackLevel (+ repeat, DeltaH/V), WhiteLevel, ActiveArea, DefaultCrop, ColorMatrix1/2, CameraCalibration, ForwardMatrix, AnalogBalance, AsShotNeutral / AsShotWhiteXY, BaselineExposure, Orientation, OpcodeList2 GainMap (lens shading) |
| DNG (lossy JPEG, floating point; opcodes other than GainMap; ProfileGainTableMap) | Unsupported / not applied (reported) |
| CR2 | Lossless JPEG with slices, borders and as-shot white balance from the maker note, black measured on the masked border. CR2 has no CFA tag and the row phase varies by model, so it is measured from the data (the green diagonal), with a Canon model-ID table as the fallback (see src/cr2.rs) |
| CR2 sRAW / mRAW | Unsupported |
| NEF / NRW, ARW, PEF and other TIFF/EP raws | Uncompressed and lossless-JPEG (incl. Sony lossless ARW) CFA data |
| Nikon compressed NEF (compression 34713): lossless and lossy type 1 / 2, 12 and 14 bit | Decoded: fixed Huffman tables + maker-note 0x0096 seeds and curve (see src/nefc.rs). BlackLevel 0x003d is read in 14-bit units. "Lossy after split" files are unsupported (preview fallback) |
| Sony compressed ARW ("cRAW", SonyRawFileType 2) | Decoded: 11-bit min/max + 7-bit delta blocks, SonyToneCurve to 14 bits, the curve's 512 black level when no BlackLevel tag is written (the first-generation bodies, e.g. the ILCE-7) |
| Panasonic / Leica RW2, RawFormat 5 (12- and 14-bit packed) | Decoded, with PanasonicRaw black / white / WB / sensor borders |
| Olympus ORF, uncompressed 16-bit (E-1, E-400…) | Decoded, with ImageProcessing black / WB / ValidBits / crop |
| Nikon "lossy after split" NEF, Sony "Compressed RAW 2", Pentax compressed PEF, RW2 RawFormat 4 and older, Olympus compressed ORF | Unsupported: no public description of these codes was found apart from GPL decoder source, which this crate may not use (clean-room). photocraft-io opens the embedded JPEG preview instead |
| Fujifilm RAF, uncompressed (X-Trans I–V, GFX and Bayer bodies since about 2010) | Decoded: 16-bit containers (either byte order), 12-bit LSB-first packing, 14-bit packing in 32-bit words; X-Trans 6×6 or Bayer 2×2 layout, black, as-shot WB, crop, RawExposureBias, orientation from the preview's EXIF |
| Fujifilm compressed RAF, early FinePix / SuperCCD RAF (no CFA TIFF) | Unsupported (no public description of the compression); preview fallback |
| CR3 | Recognised, unsupported (preview fallback where a preview is found) |
| X-Trans and other periodic non-Bayer CFAs (up to 16×16) | Demosaiced by one pattern-agnostic edge-directed method, whatever Demosaic is chosen |
Development pipeline
- Linearization table, per-position black level, scale to the white level.
- White balance (as shot; or grey-world when the file has none; or explicit multipliers), normalized so the smallest multiplier is 1, then clip to 1 so blown highlights stay white.
- Demosaic:
Bilinear,Mhc(Malvar–He–Cutler) orAhd(default) for Bayer; non-Bayer CFAs (X-Trans) always use the edge-directed generic method (demosaic_cfa). - Camera → XYZ (D50) per the DNG specification (ColorMatrix interpolated by the white's correlated colour temperature, or ForwardMatrix), or a camera look fitted to the embedded JPEG, → linear ProPhoto; exposure (BaselineExposure + user EV); the look's tone curve; gamma 1.8; 16 bits.
- Orientation.
Files without colour calibration (CR2, NEF, ARW, RW2, ORF, RAF…) have no camera matrix. Every one of
them carries a JPEG the camera rendered from the same sensor data, so fit_look estimates the
camera's rendering per file: both the sensor data (white-balanced as develop does) and the
decoded JPEG are reduced to a common grid of at most 256 cells on the long edge, and a 3×3
camera → ProPhoto matrix plus one monotone tone curve (applied per channel after exposure) are fitted
so that the developed raw matches the JPEG, by alternating isotonic regression for the curve and
weighted, ridge-regularised least squares for the matrix (residuals scaled to approximate L*,
Tukey biweights against misaligned edges and local tone mapping; clipped and near-black cells left
out). One cell in three is held out: the look is used only when it shows the same picture in colour,
the matrix is plausible and the held-out mean CIE76 ΔE drops to at most 85 % of the fallback's.
Pass it as DevelopOptions::camera_look; develop then notes "colour fitted to the camera's
embedded JPEG (mean ΔE …)". The crate cannot decode JPEG itself: photocraft-io decodes the
smallest preview at least 512 pixels long, fits and develops in one go.
Camera Raw's tuned import fits at the default exposure and as-shot white balance first,
then applies the user's Exposure, Temperature and Tint to that same rendering.
The D5100's measured image area is 4928 × 3264 at (8, 8) in a 4992 × 3280
sensor plane; it removes the border without changing levels, WB or calibration.
Measured image areas preserve an explicit file crop.
Without a usable fit (no preview, an unrelated, monochrome or differently shaped one, or a fit that
does not clearly help) the documented neutral fallback stays: the white-balanced camera channels are
treated as linear sRGB primaries, with no tone curve (plausible but flat, greyish colours; converting
to DNG gives calibrated colour), and develop says so.
Measured on 8 Nikon D3200 NEFs (12-bit lossy compressed, indoor scenes) against each file's embedded JPEG (mean CIE76 ΔE, 300-pixel grid, full develop output in sRGB): fallback 11.6–26.0, fitted 1.0–7.5; all 8 fits were accepted. The highest remaining errors are shots where the camera brightened shadows locally (Active D-Lighting), which one global curve cannot follow. The fit (preview decode included) takes about 50–70 ms on a 24 MP file. It is an estimate of the camera's look, not a measured calibration: picture styles and hue-dependent rendering are approximated.
Cameras with a profile measured against Photoshop's Camera Raw (src/cameras.rs: the Nikon D4) carry
a calibration, so no look is fitted for them. On 6 D4 NEFs against Photoshop 25.4's default Camera
Raw rendering (quarter size, medians over the frames) the measured profile is 0.048 stop from its
luminance with a mean CIE76 ΔE of 1.8; the look fitted to the embedded JPEG would be 0.30 stop and
ΔE 6.4, as it follows the camera's picture style instead. The open-time re-develop
(photocraft-io's import_raw_tuned) and the tone curve its previews use (tone_curve) take the
same look as the default open, so changing a slider does not change the colour rendering.
Tools
cargo run --release -p photocraft-raw --example rawinfo -- [--dump] [--demosaic ahd] [--png DIR] FILE...
prints what was decoded, times decode and develop, and can write sRGB PNG previews and the
embedded JPEG previews.
cargo run --release -p photocraft-io --example rawlook -- [--png DIR] FILE... times the
camera-JPEG colour fit, reports ΔE against the embedded JPEG with the neutral fallback and with the
fit, and can write 1200-pixel sRGB PNGs of both and of the JPEG; --synthetic times it on a
generated 24 MP file.