Tesseract ANPR for Android

Question

I'm using tesseract-android-tools (pre-built lib) for ANPR. But having problem when the image background is worse. Can anybody suggest how can I focus/get rectangular area of/from image taken from camera. Despite of searching the forum I'm unable to get a working example on this.

Here is my code:~

1) AndroidManifest.xml

    <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.ocrtest"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <uses-feature android:name="android.hardware.camera" />

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >            
        <activity
            android:name="com.example.ocrtest.OcrActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>    
</manifest>

2) main.xml (layout)

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/scrollView1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:padding="10dp" >

        <ImageView
            android:id="@+id/image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:contentDescription="Output"
            android:src="@drawable/ic_launcher" />
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:gravity="center"
             >
            <Button
                android:id="@+id/button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Take Pic" />
        </LinearLayout>
        <TextView
            android:id="@+id/field"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="N/A" />
    </LinearLayout>
</ScrollView>

3) OcrActivity.java

import java.io.File;
import java.io.IOException;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.media.ExifInterface;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.googlecode.tesseract.android.TessBaseAPI;

public class OcrActivity extends Activity implements View.OnClickListener {

    protected Button _button;
    protected ImageView _image;
    protected TextView _field;
    protected String _path;
    protected boolean _taken;

    protected static final String PHOTO_TAKEN = "photo_taken";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        _image = (ImageView) findViewById(R.id.image);
        _field = (TextView) findViewById(R.id.field);
        _button = (Button) findViewById(R.id.button);
        _button.setOnClickListener(this);

        File f = new File(Environment.getExternalStorageDirectory()
                + "/tessaract_languages");
        if (f.isDirectory()) {
            File imgDirectory = new File(
                    Environment.getExternalStorageDirectory() + "/images/");
            imgDirectory.mkdirs();
        } else {
            Toast.makeText(getApplicationContext(),
                    "OCR library files missing.", Toast.LENGTH_LONG).show();
            finish();
        }

        _path = Environment.getExternalStorageDirectory()
                + "/images/make_machine_example.jpg";
    }

    @Override
    public void onClick(View v) {
        switch(v.getId()) {
        case R.id.button:
            Log.i("MakeMachine", "ButtonClickHandler.onClick()");
            startCameraActivity();
            break;      
        }

    }

    protected void startCameraActivity() {
        Log.i("MakeMachine", "startCameraActivity()");
        File file = new File(_path);
        Uri outputFileUri = Uri.fromFile(file);

        Intent intent = new Intent(
                android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri);

        startActivityForResult(intent, 0);

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        Log.i("MakeMachine", "resultCode: " + resultCode);
        switch (resultCode) {
        case 0:
            Log.i("MakeMachine", "User cancelled");
            break;

        case -1:
            try {
                onPhotoTaken();
            } catch (IOException e) {
                e.printStackTrace();
            }
            break;
        }
    }

    protected void onPhotoTaken() throws IOException {
        _taken = true;
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inSampleSize = 4;
        Bitmap bitmap = BitmapFactory.decodeFile(_path, options);
        _image.setImageBitmap(bitmap);
        // _field.setVisibility(View.GONE);
        ExifInterface exif = new ExifInterface(_path);
        int exifOrientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION,ExifInterface.ORIENTATION_NORMAL);     
        int rotate = 0;
        switch (exifOrientation) {
        case ExifInterface.ORIENTATION_ROTATE_90:
            rotate = 90;
            break;
        case ExifInterface.ORIENTATION_ROTATE_180:
            rotate = 180;
            break;
        case ExifInterface.ORIENTATION_ROTATE_270:
            rotate = 270;
            break;
        }

        if (rotate != 0) {
            int w = bitmap.getWidth();
            int h = bitmap.getHeight();
            Matrix mtx = new Matrix();
            mtx.preRotate(rotate);
            bitmap = Bitmap.createBitmap(bitmap, 0, 0, w, h, mtx, false);
            bitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);
        } else {
            bitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);
        }

        TessBaseAPI baseApi = new TessBaseAPI();
        baseApi.init(Environment.getExternalStorageDirectory()+ "/tessaract_languages/", "eng");
        baseApi.setImage(bitmap);
        String recognizedText = baseApi.getUTF8Text();
        System.out.println(recognizedText);
        _field.setText(recognizedText);
        baseApi.end();      

    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        Log.i("MakeMachine", "onRestoreInstanceState()");
        if (savedInstanceState.getBoolean(OcrActivity.PHOTO_TAKEN)) {
            try {
                onPhotoTaken();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        outState.putBoolean(OcrActivity.PHOTO_TAKEN, _taken);
    }
}