Vision Text Recognition

pub package pub points pub popularity

A comprehensive Flutter plugin for advanced text recognition using platform-specific engines:

  • iOS: Apple Vision framework for high-accuracy OCR
  • Android: Google ML Kit for reliable text detection

Features

✨ Cross-Platform Support: Optimized implementations for both iOS and Android πŸ“± High Accuracy: Platform-specific engines ensure optimal recognition quality ⚑ Performance Options: Choose between speed and accuracy based on your needs 🎯 Confidence Scores: Get confidence ratings for recognized text elements πŸ“ Bounding Boxes: Precise positioning information for text blocks 🌍 Language Support: Multi-language text recognition and detection βš™οΈ Configurable: Extensive customization options for different use cases πŸ” Detailed Results: Comprehensive metadata and statistics

Platform-Specific Features

iOS (Vision Framework)

  • Language correction and detection
  • Multiple recognition levels (fast/accurate)
  • Minimum text height filtering
  • Custom model revisions
  • Advanced language preferences

Android (ML Kit)

  • Latin-based language support
  • Standardized recognition quality
  • Optimized for device performance
  • Offline processing

Installation

Add this to your package's pubspec.yaml file:

dependencies:
  vision_text_recognition: ^1.0.0

Platform Setup

iOS

Minimum iOS version: 13.0

The plugin automatically configures the Vision framework. No additional setup required.

Android

Minimum SDK version: 21

The plugin automatically includes ML Kit dependencies. No additional setup required.

Quick Start

import 'package:vision_text_recognition/vision_text_recognition.dart';

// Check if text recognition is available
bool isAvailable = await VisionTextRecognition.isAvailable();

if (isAvailable) {
  // Load your image as bytes
  List<int> imageBytes = await loadImageBytes();
  
  // Recognize text with default settings
  TextRecognitionResult result = await VisionTextRecognition.recognizeText(imageBytes);
  
  print('Recognized text: ${result.fullText}');
  print('Confidence: ${result.confidence}');
  print('Text blocks: ${result.textBlocks.length}');
}

Advanced Usage

Custom Configuration

// Create a custom configuration
final config = TextRecognitionConfig(
  recognitionLevel: RecognitionLevel.accurate,
  usesLanguageCorrection: true,
  automaticallyDetectsLanguage: true,
  minimumTextHeight: 0.02,
  preferredLanguages: ['en', 'es', 'fr'],
);

// Recognize text with custom settings
final result = await VisionTextRecognition.recognizeTextWithConfig(imageBytes, config);

Predefined Configurations

// Speed-optimized configuration
final speedConfig = TextRecognitionConfig.speed();

// Accuracy-optimized configuration  
final accuracyConfig = TextRecognitionConfig.accuracy();

// Language-specific configuration
final languageConfig = TextRecognitionConfig.languages(['en', 'es']);

Working with Results

final result = await VisionTextRecognition.recognizeText(imageBytes);

// Access full text
print('Full text: ${result.fullText}');

// Check overall confidence
if (result.isConfident()) {
  print('High confidence recognition');
}

// Process individual text blocks
for (final block in result.textBlocks) {
  print('Text: "${block.text}"');
  print('Confidence: ${(block.confidence * 100).toStringAsFixed(1)}%');
  print('Position: (${block.boundingBox.x}, ${block.boundingBox.y})');
  print('Size: ${block.boundingBox.width} x ${block.boundingBox.height}');
  
  if (block.language != null) {
    print('Language: ${block.language}');
  }
}

// Get confident text only
final confidentText = result.getConfidentText(0.8); // 80% threshold

// Find text blocks in specific region
final regionBlocks = result.getBlocksInRegion(0.0, 0.0, 0.5, 0.5); // Top-left quarter

// Get numeric blocks only
final numericBlocks = result.numericBlocks;

// Access detailed statistics
final stats = result.statistics;
print('Processing time: ${stats['processingTimeMs']}ms');
print('Average confidence: ${stats['averageConfidence']}');

Platform Information

final platformInfo = await VisionTextRecognition.getPlatformInfo();

print('Platform: ${platformInfo.platform}');
print('Engine: ${platformInfo.engine}');
print('Capabilities: ${platformInfo.capabilities}');
print('Supports language correction: ${platformInfo.supportsLanguageCorrection}');

// Get supported languages
final languages = await VisionTextRecognition.getSupportedLanguages();
print('Supported languages: $languages');

Complete Example

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:vision_text_recognition/vision_text_recognition.dart';

class TextRecognitionScreen extends StatefulWidget {
  @override
  _TextRecognitionScreenState createState() => _TextRecognitionScreenState();
}

class _TextRecognitionScreenState extends State<TextRecognitionScreen> {
  String _recognizedText = '';
  bool _isProcessing = false;
  final ImagePicker _picker = ImagePicker();

  Future<void> _pickAndRecognizeImage() async {
    final XFile? image = await _picker.pickImage(source: ImageSource.gallery);
    if (image == null) return;

    setState(() {
      _isProcessing = true;
    });

    try {
      final imageBytes = await image.readAsBytes();
      
      // Use accurate configuration for best results
      final config = TextRecognitionConfig.accuracy();
      final result = await VisionTextRecognition.recognizeTextWithConfig(
        imageBytes, 
        config
      );

      setState(() {
        _recognizedText = result.fullText;
      });
    } catch (e) {
      setState(() {
        _recognizedText = 'Error: $e';
      });
    } finally {
      setState(() {
        _isProcessing = false;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Text Recognition')),
      body: Padding(
        padding: EdgeInsets.all(16),
        child: Column(
          children: [
            ElevatedButton(
              onPressed: _isProcessing ? null : _pickAndRecognizeImage,
              child: Text('Select Image'),
            ),
            SizedBox(height: 20),
            if (_isProcessing)
              CircularProgressIndicator()
            else
              Expanded(
                child: SingleChildScrollView(
                  child: SelectableText(_recognizedText),
                ),
              ),
          ],
        ),
      ),
    );
  }
}

API Reference

Core Methods

recognizeText(List<int> imageData)

Recognizes text from image data using default settings.

Parameters:

  • imageData: Image bytes (PNG, JPEG, etc.)

Returns: Future<TextRecognitionResult>

recognizeTextWithConfig(List<int> imageData, TextRecognitionConfig config)

Recognizes text with custom configuration.

Parameters:

  • imageData: Image bytes
  • config: Recognition configuration

Returns: Future<TextRecognitionResult>

getPlatformInfo()

Gets platform capabilities and version information.

Returns: Future<PlatformInfo>

isAvailable()

Checks if text recognition is available.

Returns: Future<bool>

getSupportedLanguages()

Gets list of supported language codes.

Returns: Future<List<String>>

Models

TextRecognitionResult

Main result class containing recognized text and metadata.

Properties:

  • fullText: Complete recognized text
  • textBlocks: Individual text elements with positioning
  • confidence: Overall confidence score (0.0 to 1.0)
  • processingTimeMs: Processing time in milliseconds
  • detectedLanguage: Primary detected language

Methods:

  • isConfident([threshold]): Check if confidence meets threshold
  • getConfidentBlocks([threshold]): Get blocks above confidence threshold
  • getConfidentText([threshold]): Get text from confident blocks only
  • getBlocksInRegion(x, y, width, height): Get blocks in specific region

TextBlock

Individual text element with detailed information.

Properties:

  • text: The recognized text
  • confidence: Confidence score (0.0 to 1.0)
  • boundingBox: Position and size information
  • language: Detected language (if available)

BoundingBox

Positioning information for text elements.

Properties:

  • x, y: Top-left coordinates (normalized 0.0-1.0)
  • width, height: Dimensions (normalized 0.0-1.0)

Methods:

  • toAbsolute(imageWidth, imageHeight): Convert to absolute coordinates
  • contains(pointX, pointY): Check if point is inside box

TextRecognitionConfig

Configuration options for text recognition.

Properties:

  • recognitionLevel: Speed vs accuracy trade-off
  • usesLanguageCorrection: Enable language-based correction
  • preferredLanguages: Preferred language codes
  • minimumTextHeight: Minimum text size threshold
  • automaticallyDetectsLanguage: Enable automatic language detection

Error Handling

The plugin throws TextRecognitionException for various error conditions:

try {
  final result = await VisionTextRecognition.recognizeText(imageBytes);
} on TextRecognitionException catch (e) {
  switch (e.code) {
    case 'INVALID_IMAGE':
      print('Invalid image format');
      break;
    case 'UNSUPPORTED_PLATFORM':
      print('Platform not supported');
      break;
    case 'PROCESSING_FAILED':
      print('Recognition failed');
      break;
    default:
      print('Error: ${e.message}');
  }
}

Performance Tips

  1. Choose the right configuration: Use RecognitionLevel.fast for real-time processing, RecognitionLevel.accurate for best quality.

  2. Image preprocessing: Ensure good image quality with proper lighting and contrast.

  3. Optimize image size: Very large images may slow down processing without improving accuracy.

  4. Filter small text: Use minimumTextHeight to ignore noise and very small text.

  5. Language hints: Provide preferredLanguages when you know the expected languages.

Platform Differences

Feature iOS (Vision) Android (ML Kit)
Confidence Scores βœ… High precision βœ… Estimated
Language Detection βœ… Advanced ❌ Not available
Language Correction βœ… Available ❌ Not available
Recognition Levels βœ… Fast/Accurate βœ… Standard
Offline Processing βœ… Complete βœ… Complete
Minimum OS Version iOS 13.0+ Android API 21+

Contributing

Contributions are welcome! Please read our contributing guidelines and submit pull requests to our GitHub repository.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

Changelog

See CHANGELOG.md for a detailed history of changes.

Libraries

vision_text_recognition
vision_text_recognition_method_channel
vision_text_recognition_platform_interface