Image Smith

Privacy-friendly image tools for iOS and Android. All processing happens on your device — nothing is uploaded.

Features

• Format Conversion — Convert between JPEG, PNG, WebP, HEIC, BMP, TIFF, and AVIF
• Crop — Rectangular crop with aspect ratio presets (Free, 1:1, 4:3, 3:2, 16:9)
• Shape Crop — Crop to circle, triangle, star, heart, or hexagon shapes
• Brush Crop — Freehand paint the area to keep, everything else becomes transparent
• Rotate / Flip — Rotate 90/180/270 degrees, flip horizontal or vertical
• Lossless JPEG Operations — Rotate and crop JPEG without quality loss (DCT block rearrangement)
• Resize — Custom dimensions with aspect ratio lock (Lanczos, bilinear, nearest-neighbor)
• Compress — Reduce file size with adjustable quality
• Strip Metadata — Remove EXIF data (GPS, camera info, timestamps) — binary strip for JPEG (no re-encode)
• Editor — Multi-tool editor: apply multiple operations in sequence with undo, then export as JPEG, PNG, or WebP
• Quality Control — Adjustable quality slider for lossy formats
• Conversion History — View past operations with thumbnails and stats
• Dark Mode — System, light, or dark theme
• Haptic Feedback — Configurable tactile feedback

Supported Conversions

Format	Decode	Encode	Notes
JPEG	iOS + Android	iOS + Android	Lossless rotate/crop/EXIF strip via libjpeg-turbo
PNG	iOS + Android	iOS + Android	Lossless, compression level control
WebP	iOS + Android	iOS + Android	Lossy + lossless modes
HEIC	iOS + Android	iOS + Android	iOS: ImageIO, Android: HeifWriter
BMP	iOS + Android	iOS + Android	Built-in codec, no external dep
TIFF	iOS + Android	iOS + Android	DEFLATE compression
AVIF	Not yet supported	Not yet supported	AVIF codec not yet cross-compiled for mobile

Note: PNG, BMP, and TIFF are lossless formats — rotate, crop, and resize operations on these formats produce zero quality loss.

Android: HEIC/AVIF files from Gallery

When picking HEIC or AVIF images via "Choose from Gallery" on Android, the OS may auto-convert them to JPEG before handing the file to the app. This is Android's MediaStore / ContentResolver behavior — it transcodes HEIC/AVIF to JPEG for compatibility with apps that don't support these formats. The file you receive is already JPEG, not the original HEIC.

To work with the actual HEIC/AVIF file, use "Browse Files" (document picker) instead — it returns the raw file without conversion.

Tech Stack

• Expo SDK 54
• React Native 0.81 + React 19 + React Compiler
• expo-router — file-based navigation
• Zustand — state management with AsyncStorage persistence
• @toolsmithhq/imagecore-native — C/C++ image processing via JSI (libjpeg-turbo, libpng, libwebp, libtiff + platform APIs for HEIC)
• @shopify/react-native-skia — GPU-accelerated shape/brush crop with path clipping

Getting Started

Prerequisites

• Node.js 18+
• Android Studio (for Android) or Xcode (for iOS)

Install

npm install

Run (Development Build)

This app uses native modules and requires a development build (not Expo Go).

npx expo prebuild

npx expo run:android

npx expo run:ios

Build Standalone APK

cd android && ./gradlew assembleRelease

Output: android/app/build/outputs/apk/release/app-release.apk

Build for iOS

eas build --platform ios --profile production
eas submit --platform ios

Tests

Unit Tests (Jest)

npx jest

Tests TypeScript logic: format detection, conversion matrix, stores, error handling. (86 tests)

E2E Tests (Maestro)

Requires Maestro CLI and a running Android emulator or iOS simulator with the app installed.

# Install Maestro
brew tap mobile-dev-inc/tap
brew install mobile-dev-inc/tap/maestro

# Push sample images to Android emulator
adb push tests/samples/* /sdcard/Download/

# Run all conversion tests (42 tests — all 7 format pairs)
maestro test .maestro/convert/

# Run all operation tests (35 tests — crop/resize/compress/rotate/metadata for each format)
maestro test .maestro/operations/

# Run a single test
maestro test .maestro/convert/01_jpeg_to_png.yaml

# Run everything
maestro test .maestro/convert/ .maestro/operations/

Note: AVIF tests will fail on both iOS and Android (AVIF codec not yet cross-compiled for mobile). All other format combinations should pass.

Project Structure

app/                          # Screens (expo-router)
  (tabs)/                     # Tab navigation: Home, History, Settings
  convert/                    # Conversion flow: Pick, Processing, Result
  crop/                       # Crop flow (rectangular + shape + brush)
  rotate/                     # Rotate / Flip flow
  resize/                     # Resize flow
  compress/                   # Compress flow
  metadata/                   # Metadata view / strip flow
  editor/                     # Multi-tool editor
src/
  services/                   # Processors (crop, resize, compress, convert, metadata)
    imagecore-bridge.ts       # File URI <-> ArrayBuffer bridge for imagecore
  utils/                      # Format detection, conversion matrix, error handling
  hooks/                      # Image picker, tool processing orchestration
  stores/                     # Zustand stores (image, history, settings)
  components/                 # UI components (crop overlay, rotate config, format picker, etc.)
  constants/                  # Format definitions, tool definitions, shape definitions, theme
  types/                      # TypeScript types