javacv

# JavaCV JavaCV wraps popular computer vision and multimedia libraries—OpenCV, FFmpeg, libdc1394, FlyCapture, Spinnaker, OpenKinect, librealsense, ARToolKitPlus, flandmark, Leptonica, and Tesseract—through JavaCPP Presets, making them accessible from Java and Android. ## What it does - Loads and processes images and video via OpenCV and FFmpeg bindings - Captures frames from webcams, cameras, and video files - Records video output to files - Provides face detection with Haar cascades, contour finding, geometric transformation, and calibration utilities - Hardware-accelerated full-screen image display through `CanvasFrame` / `GLCanvasFrame` - Parallel execution helpers and direct native memory access via NIO buffers ## Key classes - `FrameGrabber` / `FrameRecorder` — abstract interfaces for capture and recording; concrete implementations include `OpenCVFrameGrabber`, `FFmpegFrameGrabber`, `OpenCVFrameRecorder`, `FFmpegFrameRecorder` - `OpenCVFrameConverter` / `Java2DFrameConverter` — convert between OpenCV `Mat`/`IplImage`, Java `BufferedImage`, Android `Bitmap`, and `Frame` - `CascadeClassifier` — loaded from XML files for object/face detection - `CanvasFrame` / `GLCanvasFrame` — display windows with optional full-screen mode - `Parallel` — execute tasks across multiple cores - `GeometricCalibrator` / `ProCamGeometricCalibrator` — camera and projector calibration ## Installation Add the platform BOM to your build. Maven: ```xml <dependency> <groupId>org.bytedeco</groupId> <artifactId>javacv-platform</artifactId> <version>1.5.14</version> </dependency> ``` Gradle: ```groovy implementation 'org.bytedeco:javacv-platform:1.5.14' ``` For GPU-accelerated OpenCV or GPL-licensed FFmpeg builds, add `opencv-platform-gpu` or `ffmpeg-platform-gpl` respectively. Binaries cover Android, iOS, Linux, macOS, and Windows. ## Requirements - Java SE 8 or newer - C++ compiler (for building from source) - Optional: Android SDK API 24+, JOCL/JOGL for OpenCL and OpenGL support - Match 32-bit and 64-bit artifacts; they cannot be mixed ## Sample: face detection from a webcam ```java import org.bytedeco.javacv.*; import org.bytedeco.opencv.opencv_core.*; import org.bytedeco.opencv.opencv_objdetect.*; import static org.bytedeco.opencv.global.opencv_core.*; import static org.bytedeco.opencv.global.opencv_imgproc.*; import static org.bytedeco.opencv.global.opencv_objdetect.*; public class FaceDetect { public static void main(String[] args) throws Exception { FrameGrabber grabber = FrameGrabber.createDefault(0); grabber.start(); CascadeClassifier classifier = new CascadeClassifier( "haarcascade_frontalface_alt.xml"); OpenCVFrameConverter.ToMat converter = new OpenCVFrameConverter.ToMat(); CanvasFrame frame = new CanvasFrame("Face Detection"); Mat gray = new Mat(); while (frame.isVisible() && (grabbed = converter.convert(grabber.grab())) != null) { cvtColor(grabbed, gray, COLOR_BGR2GRAY); RectVector faces = new RectVector(); classifier.detectMultiScale(gray, faces); for (int i = 0; i < faces.size(); i++) { Rect r = faces.get(i); rectangle(grabbed, new Point(r.x(), r.y()), new Point(r.x() + r.width(), r.y() + r.height()), new Scalar(0, 255, 0)); } frame.showImage(grabbed); } frame.dispose(); grabber.stop(); } } ``` ## Build from source Requires Maven 3.x and JavaCPP 1.5.14. Run `mvn install` in the JavaCPP, JavaCPP Presets, and JavaCV directories. Snapshot builds are also available at http://bytedeco.org/builds/. ## Links - Repository: https://github.com/bytedeco/javacv - Mailing list: http://groups.google.com/group/javacv - Discussion: https://github.com/bytedeco/javacv/discussions