How to read texts from an image (OCR) using google vision library in your Android App?

This video shows the steps to implement the google vision library to read or detect the texts and strings from an image, like an OCR (Optical Character Recognition). It demonstrates the functionality using different fonts and text sizes in the different images.

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Complete source code

package com.programmerworld.imagetotextapp;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.Manifest;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.SparseArray;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;

import com.google.android.gms.vision.Frame;
import com.google.android.gms.vision.text.TextBlock;
import com.google.android.gms.vision.text.TextRecognizer;

public class MainActivity extends AppCompatActivity {

private TextView textView;
private EditText editText;
private ImageView imageView;
private Bitmap bitmap;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE},
PackageManager.PERMISSION_GRANTED);

textView = findViewById(R.id.textView);
editText = findViewById(R.id.editText);
imageView = findViewById(R.id.imageView);
}

public void buttonReadText(View view){
try {
String stringFileName = "/storage/emulated/0/Download/" + editText.getText().toString();
bitmap = BitmapFactory.decodeFile(stringFileName);
imageView.setImageBitmap(bitmap);
TextRecognizer textRecognizer = new TextRecognizer.Builder(this).build();
Frame frameImage = new Frame.Builder().setBitmap(bitmap).build();
SparseArray<TextBlock> textBlockSparseArray = textRecognizer.detect(frameImage);
String stringImageText = "";
for (int i = 0; i<textBlockSparseArray.size();i++){
TextBlock textBlock = textBlockSparseArray.get(textBlockSparseArray.keyAt(i));
stringImageText = stringImageText + " " + textBlock.getValue();
}
textView.setText(stringImageText);
}
catch (Exception e){
textView.setText("Failed");
}
}
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.programmerworld.imagetotextapp">

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

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.ImageToTextApp">
<activity
android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />

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

</manifest>

plugins {
id 'com.android.application'
}

android {
compileSdk 31

defaultConfig {
applicationId "com.programmerworld.imagetotextapp"
minSdk 31
targetSdk 31
versionCode 1
versionName "1.0"

testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
}

dependencies {

implementation 'androidx.appcompat:appcompat:1.4.1'
implementation 'com.google.android.material:material:1.5.0'
implementation 'androidx.constraintlayout:constraintlayout:2.1.3'
testImplementation 'junit:junit:4.13.2'
androidTestImplementation 'androidx.test.ext:junit:1.1.3'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'

implementation 'com.google.android.gms:play-services-vision:20.1.3'
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.362" />

<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="153dp"
android:layout_marginTop="141dp"
android:onClick="buttonReadText"
android:text="Read Text"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />

<EditText
android:id="@+id/editText"
android:layout_width="227dp"
android:layout_height="64dp"
android:layout_marginStart="100dp"
android:layout_marginTop="40dp"
android:ems="10"
android:inputType="textPersonName"
android:text="images.jpeg"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />

<ImageView
android:id="@+id/imageView"
android:layout_width="249dp"
android:layout_height="271dp"
android:layout_marginStart="85dp"
android:layout_marginTop="51dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView"
app:srcCompat="@drawable/ic_launcher_background" />

</androidx.constraintlayout.widget.ConstraintLayout>

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