Leptonica OpenCV Java convert Mat to Pix and vise versa - opencv

Question

I use the following lept4j and OpenCV Maven dependencies:
<!-- Leptonica -->
<dependency>
<groupId>net.sourceforge.lept4j</groupId>
<artifactId>lept4j</artifactId>
<version>1.9.0</version>
</dependency>
<!-- OpenCV -->
<dependency>
<groupId>org.openpnp</groupId>
<artifactId>opencv</artifactId>
<version>3.2.0-1</version>
</dependency>
I'd like to use OpenCV and Leptonica functions together. In order to do this, I need to be able to convert Mat to Pix and Pix to Mat.
This is what I have for now:
public static Pix matToGrayscalePix(Mat mat) {
if (mat == null) {
throw new IllegalArgumentException("Recycled matrix");
}
final byte[] bytes = new byte[(int) mat.total()];
mat.get(0, 0, bytes);
ByteBuffer buff = ByteBuffer.wrap(bytes);
return Leptonica1.pixReadMem(buff, new NativeSize(buff.capacity()));
}
public static Mat pixToGrayscaleMat(Pix pix) {
if (pix == null) {
throw new IllegalArgumentException("Recycled matrix");
}
PointerByReference pdata = new PointerByReference();
NativeSizeByReference psize = new NativeSizeByReference();
int format = net.sourceforge.lept4j.ILeptonica.IFF_TIFF;
Leptonica1.pixWriteMem(pdata, psize, pix, format);
byte[] b = pdata.getValue().getByteArray(0, psize.getValue().intValue());
return new MatOfByte(b).reshape(0, pix.h);
}
But these functions doesn't work right now. What am I doing wrong ?

Answer 1

Try the following:
public static Pix convertMatToPix(Mat mat) {
MatOfByte bytes = new MatOfByte();
Imgcodecs.imencode(".tif", mat, bytes);
ByteBuffer buff = ByteBuffer.wrap(bytes.toArray());
return Leptonica1.pixReadMem(buff, new NativeSize(buff.capacity()));
}
public static Mat convertPixToMat(Pix pix) {
PointerByReference pdata = new PointerByReference();
NativeSizeByReference psize = new NativeSizeByReference();
Leptonica1.pixWriteMem(pdata, psize, pix, ILeptonica.IFF_TIFF);
byte[] b = pdata.getValue().getByteArray(0, psize.getValue().intValue());
Leptonica1.lept_free(pdata.getValue());
return Imgcodecs.imdecode(new MatOfByte(b), Imgcodecs.CV_LOAD_IMAGE_UNCHANGED);
}