Fast Bitmap Operations Library for Android

This is a collection of fast operations with images optimized for the maximum performance on Android. The alorithms are written in C++ and available using JNI.

Algorithms

1. 180 degrees inplace rotation

Performance (approximately)

Test were performed on an image with dimensions 1920x1080. Average methods' times (based on 10 test runs):

• Fast Operations Library: 2.2-2.6 ms (the fastest method)
• OpenCV: 8.9-9.6 ms (3.5-4.3 times slower than Fast Operations Library)
• Matrix method: 23-27 ms (9.9-12.4 times slower than Fast Operations Library)

2. Scaling down by factor of 2.25 using INTER_AREA interpolation

Performance (approximately)

Test were performed on an image with dimensions 1440x1080. Average methods' times (based on 10 test runs):

• Fast Operations Library: 6.4-7.0 ms (the fastest method)
• OpenCV: 42-51 ms (6.1-7.8 times slower than Fast Operations Library)

How to run the application and check performance

Clone the project, open it in Android Studio and run. Wait approximately 20 seconds and the results will be shown on the screen. The tests will run cyclically.

How to use the library in your project

• Add the following line: include ':fast_bitmap_operations_lib' to settings.graddle file.
• Add the following line: implementation project(':fast_bitmap_operations_lib') to dependencies section of application build.gradle file.

Acknowledgments

• riwnodennyk - idea and different rotation implementations.
• A discussion on different rotation methods.
• GitHub repository with different rotation methods.
• Ndk - a toolset that lets you implement parts of your app in native code, using languages such as C and C++.
• Description of OpenCV implementation.