Correct the document using Document Skew Correction feature by Huawei ML Kit in Android (Kotlin)

Introduction

In this article, we can learn how to correct the document position using Huawei ML Kit. This service automatically identifies the location of a document in an image and adjust the shooting angle to angle facing the document, even if the document is tilted. This service is majorly used in daily life. For example, if you have captured the any document, bank card, driving license etc. from the phone camera with unfair position, then this feature will adjust document angle and provides perfect position.

Precautions

• Ensure that the camera faces document, document occupies most of the image, and the boundaries of the document are in viewfinder.
• The best shooting angle is within 30 degrees. If the shooting angle is more than 30 degrees, the document boundaries must be clear enough to ensure better effects.

Requirements

1. Any operating system (MacOS, Linux and Windows).

2. Must have a Huawei phone with HMS 4.0.0.300 or later.

3. Must have a laptop or desktop with Android Studio, Jdk 1.8, SDK platform 26 and Gradle 4.6 and above installed.

4. Minimum API Level 21 is required.

5. Required EMUI 9.0.0 and later version devices.

How to integrate HMS Dependencies

1. First register as Huawei developer and complete identity verification in Huawei developers website, refer to register a Huawei ID.

2. Create a project in android studio, refer Creating an Android Studio Project.

3. Generate a SHA-256 certificate fingerprint.

4. To generate SHA-256 certificate fingerprint. On right-upper corner of android project click Gradle, choose Project Name > Tasks > android, and then click signingReport, as follows.

Note: Project Name depends on the user created name.

5. Create an App in AppGallery Connect.

6. Download the agconnect-services.json file from App information, copy and paste in android Project under app directory, as follows.

7. Enter SHA-256 certificate fingerprint and click Save button, as follows.

Note: Above steps from Step 1 to 7 is common for all Huawei Kits.

8. Click Manage APIs tab and enable ML Kit.

9. Add the below maven URL in build.gradle(Project) file under the repositories of buildscript, dependencies and allprojects, refer Add Configuration.

10. Add the below plugin and dependencies in build.gradle(Module) file.

11. Now Sync the gradle.

12. Add the required permission to the AndroidManifest.xml file.

Let us move to development

I have created a project on Android studio with empty activity let us start coding.

In the MainActivity.kt we can find the business logic.

In the activity_main.xml we can create the UI screen.

Demo

Tips and Tricks

1. Make sure you are already registered as Huawei developer.

2. Set minSDK version to 21 or later, otherwise you will get AndriodManifest merge issue.

3. Make sure you have added the agconnect-services.json file to app folder.

4. Make sure you have added SHA-256 fingerprint without fail.

5. Make sure all the dependencies are added properly.

Conclusion

In this article, we have learnt to correct the document position using Document Skew Correction feature by Huawei ML Kit. This service automatically identifies the location of a document in an image and adjust the shooting angle to angle facing the document, even if the document is tilted.

I hope you have read this article. If you found it is helpful, please provide likes and comments.

Reference

ML Kit — Document Skew Correction

I have created a project on Android studio with empty activity let us start coding.

In the MainActivity.kt we can find the business logic.