OpenCV: Overview of its features and how to use it in React native for image processing

OpenCV is undoubtedly one of the most widely used software libraries that you can find on the internet. This platform is certainly free to use and is designated to offer a general infrastructure for computer vision applications. Also, it can fast-track the use of machine perception in commercially available creations. Together with React Native, this module will enable you to process images on mobile devices and other free sources.

OpenCV features and how to use it

Additionally, this module is operating under a BSD license, which means there is minimal to no restrictions on the use of the library. This allows commercial entities are able to employ the code and tweak it as they want. So, if you have ever wondered how to process your images using OpenCV with React Native, then you’re in the right place. Now, we would like to show you guys the overview of its features, and also how to use it in React Native.

Let’s get into it!

Overview of OpenCV’s features

#1. This is an open-source, cross-platform software library

OpenCV is a cross-platform library, enabling users on different operating systems to use it without complications. It is even accessible on mobile systems like iOS and Android, making it a truly portable library. Now, it plays a major role in real-time operation which is very important in today’s systems. By using it, one can process images and videos to identify objects, faces, or even the handwriting of a human.

#2. Vast algorithms for multiple interfaces

OpenCV offers users access to over 2,500 algorithms, both classic and state-of-the-art. This vast library allows programmers to perform a multitude of tasks in their software such as extracting 3D models of objects, removing red eyes, following eye movements, and more. As a result, multiple interfaces are integrated into the module. This will benefit a lot for both the developers and the purchasers.

#3. Extensive usage of OpenCV

OpenCV usage
OpenCV usage

OpenCV is being used by giant companies and startups, as well as organizations in countries all over the world to conduct multifarious tasks. This gives users assurance that they are onboarding a library that is being used extensively. Moreover, this module has a vast community where users can ask for assistance and offer help to their fellow developers in case they have questions regarding codes or the platform.

#4. Core functionality

This module covers the basic data structures such as Scalar, Point, Range, etc., that are used to build the module’s applications. In addition to these, it also includes the multidimensional array Mat, which is used to store the images. Also, the Java library of this platform, this module is included as a package with the name org.opencv.core. As a result, the vast functionality can make up almost everything included in your business.

Application of OpenCV

So here we have listed down some of the major domains where OpenCV is heavily used.

  • Robotics Application
  • Navigation
  • Medicine Application
  • Industrial Automation Application
  • Assembly
  • Security Application
  • Transportation Application

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How to use it in React Native for image processing?

Basic preparation

#1: react-native init reactNativeOpenCvTutorial

#2: Run downloadAndInsertOpenCV.sh script in your project’s catalog (can be found here) which downloads and inserts files for both Android and iOS. The paths in the file might not match your preferences so you may need to change them.

Example: Android for OpenCV

#1: Open your project in Android Studio.

#2: Then, follow the tips in Android Studio for synchronizing your project.

#3: After that, you should download the newest version for Android.

#4: Import this module to Android Studio – from File -> New -> Import Module, then choose sdk/java folder in the unzipped archive.

#5: Update build.gradle under imported module to update 4 fields to match your project’s build.gradle:

  • compileSdkVersion
  • buildToolsVersion
  • minSdkVersion
  • targetSdkVersion.

#6: Add module dependency: Application -> Module Settings, and select the “Dependencies” tab. Click the “+” icon at the bottom, choose “Module Dependency” and select the imported OpenCV module. For Android Studio v1.2.2, to access Module Settings in the Project view, right-click the dependent module -> Open Module Settings. Click on the “+”, select “Module dependency” and select the library from the list.

Android module settings

#7: Inside android/app/src/java, create a package called i.e. “com.reactlibrary”.

#8 Update your Manifest with proper permissions:

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

#9: Create a file RNOpenCvLibraryModule.java inside your newly created package, then building a file called RNOpenCvLibraryPackage.java inside your newly created package.

#10: Add proper imports in your MainApplication.java file, add your package to the list and proper code to the MainApplication class like this:

 Imports:

import com.reactlibrary.RNOpenCvLibraryPackage;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import android.util.Log;

Final step: JavaScript

#1: Inside your src folder create a folder named e.g. “NativeModules” and also a file named OpenCV.js and fill it with:

 import { NativeModules } from 'react-native';

export default NativeModules.RNOpenCvLibrary;

#2: We will be using some third-party libraries for quick setup. In order to do that, open up the terminal and type:

 npm i --save react-native-svg
npm i --save react-native-camera
npm i --save react-native-easy-toast

#3: Don’t forget to link the libraries: react-native link.

#4: Note to yourself: if you encounter build problems for Android connected to the camera, refer to my build.gradle file, especially maven { url “https://jitpack.io” }, and resync the project in Android Studio. So, if you have errors related to Google Play services, check this issue on GitHub. Also, if you have errors related to react-native-camera, check the master branch by changing the version in package.json like this:

"react-native-camera": "git+https://git@github.com/react-native-community/react-native-camera"

Final words

That should be it! Here is the overview of OpenCV’s features and how to use it in React Native for image processing. All in all, this module gives you a smooth, seamless experience when deploying it in React Native. This can be much better for your image processing, and as a result, a better outcome for your eCommerce business.

We – ArrowHiTech is proud to be one of the most well-established outsourcing companies all around the world. That is to say, with over 12 years of experience, we can provide the best React native app development services for your business. Also, if you want to go through our showcase, you should visit our product page here: MageSolution or our portfolio: ArrowHiTech portfolio.

ArrowHiTech services

If you have any questions, don’t hesitate to contact us via email support@arrowhitech.com or our phone number +84 243 7955 813. We would love to hear every feedback from you guys.

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