Raw2DNG - Android RAW to DNG/JPEG Converter

An Android application that converts proprietary RAW camera files (CR2, ARW, NEF, ORF, RAF, RW2, PEF, SRW, etc.) to Adobe DNG format and/or JPEG. It uses LibRaw for RAW file processing and the Adobe DNG SDK for DNG file creation.

Features

Core Conversion

• ✅ Convert RAW files to Adobe DNG format
• ✅ Convert RAW files to high-quality JPEG
• ✅ Parallel conversion with configurable thread count (1 to N CPU cores)
• ✅ Visual conversion progress with thumbnail grid and status overlays
• ✅ Overwrite confirmation for already-converted files
• ✅ Complete EXIF/metadata preservation in both DNG and JPEG output

File Management

• ✅ Browse RAW files with thumbnail previews
• ✅ Filter chips: All / Not DNG / Not JPEG
• ✅ Hide or dim already-converted images
• ✅ Gallery view for converted files with DNG/JPEG/All filters
• ✅ Multi-select mode with batch operations
• ✅ Regenerate converted files from original RAW sources

Preview & Metadata

• ✅ Fullscreen image preview with swipe navigation
• ✅ Thumbnail strip (gutter) with conversion status badges
• ✅ EXIF/metadata overlay with detailed camera, lens, exposure, and GPS info
• ✅ Zoom controls and file size display
• ✅ Double-tap to open fullscreen preview

Integration

• ✅ Auto-open single DNG in Snapseed (optional)
• ✅ Share single JPEG via Android share sheet (optional)
• ✅ Auto-navigate to Gallery on conversion completion
• ✅ Open converted files in external apps

User Experience

• ✅ Material 3 theming with dynamic colors
• ✅ Three-tab interface: Convert, Gallery, Settings
• ✅ Configurable JPEG quality, chroma subsampling, and Huffman optimization
• ✅ Hierarchical RAW format selection by manufacturer
• ✅ Screen rotation handling with state preservation
• ✅ Docker-based build system (no Android Studio required!)

Quick Start with Docker 🐳

Don't have Android Studio? Use Docker to build the APK with zero setup!

# 1. Install Docker (if not already installed)
# See: https://docs.docker.com/get-docker/

# 2. Clone the repository with submodules
git clone --recursive <repo-url>
cd raw2dng2

# Or if already cloned, initialize submodules
git submodule update --init --recursive

# 3. (Optional) Add Adobe DNG SDK for real conversion
# Download from: https://helpx.adobe.com/camera-raw/digital-negative.html
# Then: cp /path/to/dng_sdk/source/*.{cpp,h} app/src/main/cpp/dng_sdk/

# 4. Build the APK (one command!)
sudo make build
# or: ./docker-build.sh

# 5. Your APK is ready!
ls output/app-debug.apk

# 6. Install on connected device
adb install output/app-debug.apk

That's it! No Android Studio, no SDK setup, just Docker and you're done.

For detailed Docker instructions, see DOCKER_BUILD.md.

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Prerequisites

Choose your build method:

• Option A: Docker Build (Recommended - No Android tools needed!)

  • Only requires: Docker and Docker Compose
  • See: DOCKER_BUILD.md

• Option B: Android Studio Build (For Android developers)

  • Requires: Android Studio, NDK, CMake
  • See instructions below

Option B: Development Environment (Android Studio)

1. Android Studio (Arctic Fox or newer)

   • Download from: https://developer.android.com/studio

2. Android NDK (r21 or newer)

   • Install via Android Studio SDK Manager
   • Go to: Tools → SDK Manager → SDK Tools → NDK (Side by side)

3. CMake (3.22.1 or newer)

   • Install via Android Studio SDK Manager
   • Go to: Tools → SDK Manager → SDK Tools → CMake

Adobe DNG SDK

IMPORTANT: You must download and install the Adobe DNG SDK before building this project.

Download Instructions:

1. Visit Adobe's DNG SDK page:

   • https://helpx.adobe.com/camera-raw/digital-negative.html
   • Or search for "Adobe DNG SDK download"

2. Download the latest version (1.6 or newer recommended)

3. Extract the downloaded ZIP file

4. Copy SDK files to the project:

   # Navigate to the extracted SDK directory
   cd /path/to/dng_sdk_x_x/
   
   # Copy all source files to the project
   cp dng_sdk/source/*.cpp /path/to/raw2dng2/app/src/main/cpp/dng_sdk/
   cp dng_sdk/source/*.h /path/to/raw2dng2/app/src/main/cpp/dng_sdk/

   Or use the provided helper script:

   # From the project root directory
   ./download_dng_sdk.sh
   # Follow the instructions, download the SDK, then:
   ./download_dng_sdk.sh --extract

5. Verify installation:

   ls app/src/main/cpp/dng_sdk/dng_*.cpp
   # Should show multiple DNG SDK source files

Building the Project

Option 1: Android Studio (Recommended)

1. Open Android Studio
2. Select "Open an Existing Project"
3. Navigate to the raw2dng2 directory
4. Wait for Gradle sync to complete
5. Ensure the Adobe DNG SDK is installed (see above)
6. Click "Build" → "Make Project" or press Ctrl+F9 (Windows/Linux) or Cmd+F9 (Mac)
7. Connect an Android device or start an emulator
8. Click "Run" → "Run 'app'" or press Shift+F10

Option 2: Command Line

# From project root directory
./gradlew assembleDebug

# Install on connected device
./gradlew installDebug

# Or build and install in one command
./gradlew build installDebug

Build Output

• Debug APK: app/build/outputs/apk/debug/app-debug.apk
• Release APK: app/build/outputs/apk/release/app-release.apk (after ./gradlew assembleRelease)

Installation

Install on Device

1. Enable "Developer Options" on your Android device:

   • Go to Settings → About Phone
   • Tap "Build Number" 7 times
   • Go back to Settings → Developer Options
   • Enable "USB Debugging"

2. Connect device via USB

3. Install the app:

   adb install app/build/outputs/apk/debug/app-debug.apk

   Or use Android Studio's "Run" button.

Usage

Application Overview

The app uses a three-tab interface:

1. Convert Tab - Browse and convert RAW files
2. Gallery Tab - View and manage converted images
3. Settings Tab - Configure app preferences

Converting RAW Files

1. Launch the App

   • Open "Raw2DNG" from your device's app drawer

2. Browse RAW Files

   • The Convert tab displays RAW files from your device with thumbnails
   • Use filter chips to show: All / Not DNG / Not JPEG
   • Already-converted files appear dimmed (or hidden, based on settings)

3. Select Files

   • Single-tap to toggle file selection
   • Double-tap to open fullscreen preview
   • Selected files show a checkmark overlay

4. Convert Files

   • Tap the DNG or JPEG button to start conversion
   • A progress overlay shows:
     • Thumbnail grid with per-file status (pending, in-progress, success, error)
     • Progress bar with X/Y count
     • Log view (toggle with Log button)
   • Previously converted files require tap to confirm overwrite
   • Conversion runs in parallel (configurable 1-N threads)

5. After Conversion

   • Auto-navigate to Gallery (optional, with countdown)
   • Or tap Done to dismiss the overlay
   • Single DNG can auto-open in Snapseed (if enabled)
   • Single JPEG can open share sheet (if enabled)

Gallery Tab

• View converted DNG and JPEG files with thumbnails
• Filter by: DNG Only / JPEG Only / All
• Single-tap opens file in external app
• Double-tap opens fullscreen preview
• Long-press enables multi-select mode:
  • Preview: Open selected images in fullscreen viewer
  • Regenerate: Re-convert from original RAW files
  • Open with: Send to external app
• Clear folder button (respects current filter)
• File size displayed on thumbnails

Fullscreen Preview

• Swipe left/right to navigate between images
• Thumbnail strip at bottom shows all images with:
  • D/J badges for conversion status (Convert tab)
  • Green checkmarks for selected items (Gallery)
• Tap info button to show EXIF/metadata overlay:
  • Camera, lens, exposure, shooting info
  • Dimensions, GPS, date/time
  • Advanced view shows raw JSON metadata
• Zoom controls available
• Toggle selection with checkbox button

Settings Tab

• Auto-Navigate Timeout: 0-30 seconds countdown after conversion
• Conversion Threads: 1 to N CPU cores for parallel processing
• Enabled RAW Types: Select formats by manufacturer (Canon, Nikon, Sony, etc.)
• Hide Already Converted: Hide vs dim converted images in Convert tab
• Open Single DNG in Snapseed: Auto-open after single DNG conversion
• Share Single JPEG: Open share sheet after single JPEG conversion
• JPEG Quality Settings: Quality (1-100), chroma subsampling, Huffman optimization
• View Open Source Licenses: Attribution for LibRaw, DNG SDK, cJSON, libjpeg

Output Directories

Converted files are saved to public storage:

/storage/emulated/0/Pictures/Raw2DNG/
├── *.dng                     # Converted DNG files
└── JPEG/
    └── *.jpg                 # Converted JPEG files

Access files via:

• Gallery app or any file manager
• ADB: adb pull /storage/emulated/0/Pictures/Raw2DNG/
• USB file transfer (MTP mode)

Supported RAW Formats

The app uses LibRaw for RAW file reading, supporting formats organized by manufacturer:

Manufacturer	Formats
Canon	CR2, CR3, CRW
Nikon	NEF, NRW
Sony	ARW, SRF, SR2
Fujifilm	RAF
Olympus/OM System	ORF
Panasonic/Lumix	RW2, RAW
Pentax	PEF
Samsung	SRW
Hasselblad	3FR, FFF
Phase One/Leaf	IIQ
Kodak	DCR, KDC
Epson	ERF
Mamiya	MEF

Note: You can enable/disable specific formats in Settings → Enabled RAW File Types.

Known Limitations

1. Scoped Storage: Files created by previous app installations cannot be overwritten directly. Delete from Gallery first, then re-convert.
2. DNG Thumbnail Orientation: Android's loadThumbnail() doesn't apply EXIF orientation for DNG files; app manually rotates.
3. Package Visibility: AndroidManifest must declare Snapseed package for integration to work on Android 11+.
4. Camera Color Matrices: Some newer cameras may need hardcoded color matrices for accurate colors.

Troubleshooting

Build Errors

"Adobe DNG SDK source files not found"

• Download and install the Adobe DNG SDK as described in Prerequisites

"NDK not configured"

• Install Android NDK via Android Studio SDK Manager

"CMake not found"

• Install CMake via Android Studio SDK Manager

Runtime Issues

Install fails with INSTALL_FAILED_UPDATE_INCOMPATIBLE

adb uninstall com.raw2dng && adb install output/app-debug.apk

Purple cast in dark images

• Check per-channel black level handling in libraw_to_dng.cpp

Wrong colors on specific camera

• May need camera-specific color matrix in libraw_to_dng.cpp

Corrupt output during parallel conversion

• Ensure LIBRAW_NOTHREADS is NOT defined in CMakeLists.txt

File gets "(1)" suffix on overwrite

• File was created by previous app installation; delete from Gallery first

RAW files not appearing

• Check Settings → Enabled RAW File Types

License

This project uses multiple open-source components with various licenses:

• LibRaw: LGPL 2.1 / CDDL 1.0 dual license
• Adobe DNG SDK: Adobe license (must download separately)
• cJSON: MIT license
• libjpeg: Independent JPEG Group license
• Android/Kotlin Libraries: Apache 2.0

View full license details in the app via Settings → View Open Source Licenses.

Important: The Adobe DNG SDK has its own license agreement. You must comply with Adobe's licensing terms when using the DNG SDK.

Resources

• Adobe DNG SDK
• Adobe DNG Specification
• LibRaw Documentation
• Android NDK Documentation
• JNI Guide

Support

For issues or questions:

1. Check the Troubleshooting section above
2. Review LibRaw and Adobe DNG SDK documentation
3. Check Android NDK documentation for native build issues

Acknowledgments

• [raw2dng2] (https://github.com/fwibisono87/raw2dng2) the skeleton for this project
• LibRaw for RAW file processing
• Adobe for the DNG SDK
• cJSON for JSON serialization
• Independent JPEG Group for libjpeg
• Android Open Source Project
• JetBrains for Kotlin