You can use java.awt.image.BufferedImage as interface.
Just convert your org.opencv.core.Mat object to java.awt.image.BufferedImage and then take the result object to convert it to org.bytedeco.javacpp.opencv_core.Mat.
Now, these are the functions that you will need:
1) Convert org.opencv.core.Mat to java.awt.image.BufferedImage:
public BufferedImage matToBufferedImage(Mat frame) {
int type = 0;
if (frame.channels() == 1) {
type = BufferedImage.TYPE_BYTE_GRAY;
} else if (frame.channels() == 3) {
type = BufferedImage.TYPE_3BYTE_BGR;
}
BufferedImage image = new BufferedImage(frame.width() ,frame.height(), type);
WritableRaster raster = image.getRaster();
DataBufferByte dataBuffer = (DataBufferByte) raster.getDataBuffer();
byte[] data = dataBuffer.getData();
frame.get(0, 0, data);
return image;
}
2) Convert java.awt.image.BufferedImage to org.bytedeco.javacpp.opencv_core.Mat:
public Mat bufferedImageToMat(BufferedImage bi) {
OpenCVFrameConverter.ToMat cv = new OpenCVFrameConverter.ToMat();
return cv.convertToMat(new Java2DFrameConverter().convert(bi));
}
Make sure to have all the necessary jars and imports.
You could go deeper into JNI stuff, but for test use cases, this should be enough.