http://enfanote.blogspot.com/2013/06/converting-java-bufferedimage-to-opencv.html
BufferedImage to Mat
Note: this only works if the image is of type BufferedImage.TYPE_3BYTE_BGR
BufferedImage image = myBufferedImage;
byte[] data = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
Mat mat = new Mat(image.getHeight(), image.getWidth, CvType.CV_8UC3);
mat.put(0, 0, data);
Mat to BufferedImage
Mat mat = myMat;
byte[] data = new byte[mat.rows()*mat.cols()*(int)(mat.elemSize())];
mat.get(0, 0, data);
if (mat.channels() == 3) {
for (int i = 0; i < data.length; i += 3) {
byte temp = data[i];
data[i] = data[i + 2];
data[i + 2] = temp;
}
}
BufferedImage image = new BufferedImage(mat.cols(), mat.rows(), BufferedImage.TYPE_3BYTE_BGR);
image.getRaster().setDataElements(0, 0, mat.cols(), mat.rows(), data);