Raw2DNG - Android RAW to DNG Converter

A proof-of-concept Android application that converts proprietary RAW files (CR2, ARW, NEF, etc.) to Adobe DNG format using the Adobe DNG SDK.

Features

• ✅ Select multiple RAW files from device storage
• ✅ Queue-based conversion processing
• ✅ Progress tracking with detailed logs
• ✅ Support for various RAW formats (CR2, ARW, NEF, RAF, ORF, etc.)
• ✅ Native C++ implementation using Adobe DNG SDK
• ✅ Simple, functional UI for proof-of-concept testing
• ✅ 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
git clone <repo-url>
cd raw2dng2

# 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!)
make build
# or: ./docker-build.sh

# 5. Your APK is ready!
ls 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

Testing the Conversion

1. Launch the App

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

2. Check SDK Status

   • The log at the bottom will show SDK availability status
   • If SDK is available: "SDK Status: Adobe DNG SDK (version info)"
   • If SDK is missing: Warning messages will appear

3. Select RAW Files

   • Tap "SELECT RAW FILES" button
   • Grant storage permissions if prompted
   • Navigate to your RAW files (CR2, ARW, NEF, etc.)
   • Select one or multiple files
   • The app will show "X file(s) selected"

4. Convert Files

   • Tap "CONVERT TO DNG" button
   • Monitor progress in the progress bar and log
   • Converted files are saved to: /storage/emulated/0/Android/data/com.raw2dng/files/Documents/Raw2DNG/

5. Check Results

   • Success: ✓ filename.CR2 -> filename.dng
   • Failure: ✗ filename.CR2: [error message]
   • Final summary shows successful and failed conversions

Accessing Converted Files

Converted DNG files are saved to the app's external files directory:

/storage/emulated/0/Android/data/com.raw2dng/files/Documents/Raw2DNG/

You can access these files using:

• Android File Manager app
• ADB: adb pull /storage/emulated/0/Android/data/com.raw2dng/files/Documents/Raw2DNG/
• USB file transfer (MTP mode)

Supported RAW Formats

The Adobe DNG SDK supports reading many proprietary RAW formats, including:

• Canon: CR2, CR3, CRW
• Nikon: NEF, NRW
• Sony: ARW, SRF, SR2
• Fujifilm: RAF
• Olympus: ORF
• Panasonic: RW2, RAW
• Pentax: PEF, DNG
• Adobe: DNG
• And many more...

Note: Format support depends on the Adobe DNG SDK version. Some newer proprietary formats may require the latest SDK version.

Troubleshooting

Build Errors

"Adobe DNG SDK source files not found"

• Solution: Download and install the Adobe DNG SDK as described above
• The app will still compile but create placeholder files instead of real conversions

"NDK not configured"

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

"CMake not found"

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

Runtime Errors

"Storage permission denied"

• Solution: Grant storage permissions when prompted
• Or manually: Settings → Apps → Raw2DNG → Permissions → Storage → Allow

"Conversion failed" with SDK warnings

• Solution: Ensure Adobe DNG SDK is properly installed
• Check that .cpp and .h files are in app/src/main/cpp/dng_sdk/
• Rebuild the project: Build → Clean Project, then Build → Rebuild Project

"File not found" or "Cannot read file"

• Solution: Ensure RAW files are accessible on device storage
• Try copying RAW files to a public directory like Downloads or DCIM

Testing Without DNG SDK

The app can be built and run without the Adobe DNG SDK for UI testing purposes:

• It will create placeholder DNG files instead of real conversions
• Useful for testing the queue mechanism and UI flow
• Real conversion requires the SDK to be installed

Project Structure

raw2dng2/
├── app/
│   ├── src/
│   │   ├── main/
│   │   │   ├── cpp/                    # Native C++ code
│   │   │   │   ├── dng_sdk/           # Adobe DNG SDK files (user-provided)
│   │   │   │   ├── CMakeLists.txt     # CMake build configuration
│   │   │   │   ├── dng_converter.cpp  # DNG conversion logic
│   │   │   │   ├── raw2dng_jni.cpp    # JNI bindings
│   │   │   │   └── xmp_stub.cpp       # XMP SDK stub
│   │   │   ├── java/com/raw2dng/      # Kotlin/Java code
│   │   │   │   ├── MainActivity.kt    # Main UI activity
│   │   │   │   ├── DNGConverter.kt    # JNI wrapper
│   │   │   │   └── ConversionQueue.kt # Queue manager
│   │   │   ├── res/                   # Android resources
│   │   │   └── AndroidManifest.xml    # App manifest
│   │   └── build.gradle               # App-level build config
│   └── build.gradle                   # Module-level build config
├── build.gradle                       # Project-level build config
├── settings.gradle                    # Project settings
├── download_dng_sdk.sh               # Helper script for SDK setup
└── README.md                         # This file

Technical Details

Architecture

• UI Layer: Kotlin with Android SDK

  • File picker using Storage Access Framework
  • Coroutines for asynchronous operations
  • LiveData for UI updates

• Business Logic: Kotlin

  • Queue-based task processing
  • Error handling and logging
  • File I/O operations

• Native Layer: C++ with JNI

  • Adobe DNG SDK integration
  • RAW file parsing and DNG writing
  • Exception handling and error reporting

Build Configuration

• Min SDK: Android 7.0 (API 24)
• Target SDK: Android 14 (API 34)
• NDK: C++17 with STL support
• ABIs: arm64-v8a, armeabi-v7a, x86, x86_64

Dependencies

• AndroidX Core KTX
• AndroidX AppCompat
• Material Design Components
• Kotlin Coroutines
• Adobe DNG SDK (external, user-provided)

Known Limitations

This is a proof-of-concept application with the following limitations:

1. UI/UX: Minimal, functional interface - not production-ready
2. Error Handling: Basic error messages - could be more user-friendly
3. File Management: Limited file browsing capabilities
4. Performance: Sequential processing - could be parallelized
5. Format Detection: No automatic format validation
6. Metadata: XMP support disabled (qDNGUseXMP=0)
7. Testing: Limited testing on various RAW formats
8. Icon: Placeholder icon - needs proper app icon

Future Improvements

Potential enhancements for production version:

• Parallel conversion processing
• Better error handling and user feedback
• RAW format validation before conversion
• Conversion settings/options (compression, preview size, etc.)
• Progress notifications for background processing
• File browser with RAW file filtering
• Batch operations (delete, share, etc.)
• XMP metadata preservation
• Custom output directory selection
• App icon and branding
• Comprehensive testing suite

License

This project structure and application code is provided as-is for educational purposes.

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

Resources

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

Support

This is a proof-of-concept project. For issues or questions:

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

Acknowledgments

• Adobe for the DNG SDK
• Android Open Source Project
• JetBrains for Kotlin