ml_dual_iso_rs

A pure-Rust rewrite of the Magic Lantern cr2hdr dual-ISO post-processing tool.

Converts dual-ISO RAW files (CR2 / DNG) captured by Magic Lantern-equipped Canon cameras into a single high-dynamic-range DNG, recovering roughly 3 extra stops of dynamic range compared to a single-ISO exposure.

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Features

• Pure Rust – no dcraw, no exiftool, no external C tools required
• rawler integration for native CR2 / Canon DNG decoding
• AMaZE-inspired edge-aware interpolation (mean2/3 or edge mode)
• Chroma smoothing (2×2 / 3×3 / 5×5 median), dithering, bad-pixel correction, stripe-fix
• White balance modes: Auto (graymax / graymed), EXIF, Kelvin temperature, Custom multipliers
• Parallel processing of multiple files via rayon
• CLI (cr2hdr) – drop-in replacement for the original tool
• GUI (dual-iso-gui) – egui/eframe native desktop application with drag-and-drop
• xtask task runner for development workflow

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Quick Start

# Clone
git clone https://github.com/Tinnci/ml_dual_iso_rs.git
cd ml_dual_iso_rs

# Run the GUI
cargo xtask run-gui

# Convert a single file via CLI
cargo xtask run-cli -- my_shot.CR2

# Convert with options
cargo xtask run-cli -- --iso-100 100 --iso-1600 1600 --amaze --cs3x3 my_shot.CR2

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Workspace Layout

ml_dual_iso_rs/
├── Cargo.toml               # workspace root (resolver v3, edition 2024)
├── xtask/                   # task runner  (cargo xtask <task>)
├── crates/
│   ├── dual-iso-core/       # core library – pipeline algorithms
│   └── dual-iso-gui/        # egui/eframe desktop GUI
├── bins/
│   └── cr2hdr/              # CLI binary (clap)
└── original_src/            # original C source for reference

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xtask Tasks

Command	Description
cargo xtask check	fmt --check + clippy -D warnings
cargo xtask fmt	Auto-format all crates
cargo xtask test	Run all unit tests
cargo xtask dist	Release build → dist/ folder
cargo xtask run-cli [-- ARGS]	Build & run cr2hdr CLI, pass extra args after --
cargo xtask run-gui	Build & run the GUI application

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CLI Usage

cr2hdr [OPTIONS] <FILES>...

Options:
  --iso-100 <N>       Low-ISO value (default: auto-detect)
  --iso-1600 <N>      High-ISO value (default: auto-detect)
  --amaze             Use AMaZE edge-aware interpolation (slower, better quality)
  --cs2x2             Chroma smooth 2×2
  --cs3x3             Chroma smooth 3×3 (default)
  --cs5x5             Chroma smooth 5×5
  --no-dither         Disable output dithering
  --no-fixbp          Skip bad-pixel correction
  --wb-kelvin <K>     Set white balance by colour temperature in Kelvin
  --compress          Apply lossless DNG compression
  -o <DIR>            Output directory (default: same as input)

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Pipeline Overview

CR2/DNG input
    │
    ▼
rawler decode  →  RawImage (u16 Bayer mosaic)
    │
    ├─► detect ISO lines   (row-variance analysis)
    ├─► deinterlace        (split bright / dark planes)
    ├─► interpolate        (mean2/3 or AMaZE edge)
    ├─► blend              (EV-space sigmoid blend)
    ├─► chroma smooth      (median filter on R-G, B-G)
    ├─► bad pixels         (neighbourhood median)
    ├─► stripe fix         (per-row offset correction)
    ├─► white balance      (scale R/B channels)
    └─► dither             (Gaussian noise σ=0.5)
         │
         ▼
      DNG output  (hand-crafted TIFF/DNG writer)

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Requirements

• Rust 1.80+ (edition 2024)
• macOS / Linux / Windows (cross-platform)

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Credits

Original C implementation by a1ex and contributors: Magic Lantern dual_iso module.
AMaZE algorithm from RawTherapee.
Kelvin→RGB conversion from CIE daylight locus formulae.

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License

Licensed under the GNU General Public License v2.0 – see LICENSE.