android mat 转 bitmap

Bitmap bmp = null;
Mat tmp = new Mat (height, width, CvType.CV_8U, new Scalar(4));
try {
    //Imgproc.cvtColor(seedsImage, tmp, Imgproc.COLOR_RGB2BGRA);
    Imgproc.cvtColor(seedsImage, tmp, Imgproc.COLOR_GRAY2RGBA, 4);
    bmp = Bitmap.createBitmap(tmp.cols(), tmp.rows(), Bitmap.Config.ARGB_8888);
    Utils.matToBitmap(tmp, bmp);
}
catch (CvException e){Log.d("Exception",e.getMessage());}