How to use CLAHE of opencv in android?

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OpenCV

Hello i am new to opencv and i want to use CLAHE in my app but i don't know.please help me.i tried following code

int lnth = grayscale.getByteCount();

                ByteBuffer dst = ByteBuffer.allocate(lnth);
                grayscale.copyPixelsToBuffer(dst);
                byte[] byteArray = dst.array();

                Log.e("byte array", byteArray + "");
                Mat orgImage = new Mat();
                orgImage.put(0, 0, byteArray);

                Mat labImage = new Mat(grayscale.getHeight(), grayscale.getWidth(), CvType.CV_8UC1);
                Imgproc.cvtColor(orgImage, labImage, Imgproc.COLOR_BGR2Lab);

                CLAHE clahe = Imgproc.createCLAHE();
                CLAHEmat = new Mat(grayscale.getHeight(), grayscale.getWidth(), CvType.CV_8UC1);
                clahe.apply(labImage, CLAHEmat);

                Utils.matToBitmap(CLAHEmat, histogram);

but it shows error:

E/cv::error(): OpenCV Error: Assertion failed ((scn == 3 || scn == 4) && (depth == CV_8U || depth == CV_32F)) in void cv::cvtColor(cv::InputArray, cv::OutputArray, int, int), file /builds/master_pack-android/opencv/modules/imgproc/src/color.cpp, line 8175
04-14 12:59:47.420 2085-2085/? E/org.opencv.imgproc: imgproc::cvtColor_11() caught cv::Exception: /builds/master_pack-android/opencv/modules/imgproc/src/color.cpp:8175: error: (-215) (scn == 3 || scn == 4) && (depth == CV_8U || depth == CV_32F) in function void cv::cvtColor(cv::InputArray, cv::OutputArray, int, int)
04-14 12:59:47.437 2085-2085/? E/AndroidRuntime: FATAL EXCEPTION: main
                                                 Process: com.atlassoftweb.omrsample, PID: 2085
                                                 CvException [org.opencv.core.CvException: cv::Exception: /builds/master_pack-android/opencv/modules/imgproc/src/color.cpp:8175: error: (-215) (scn == 3 || scn == 4) && (depth == CV_8U || depth == CV_32F) in function void cv::cvtColor(cv::InputArray, cv::OutputArray, int, int)
                                                 ]

What I have tried:

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import org.opencv.android.Utils;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Scalar;
import org.opencv.imgproc.CLAHE;
import org.opencv.imgproc.Imgproc;

import java.nio.ByteBuffer;

public class sample extends AppCompatActivity {

ImageView img;
Bitmap original, grayscale, histogram, resize, threshold;
int fixedwidth = 480;
int fixedheight = 800;
Button btn_original, btn_grayscale, btn_histogram, btn_resize, btn_threshold;
Mat rgbMat;
Mat grayMat;
Mat CLAHEmat;

static {
System.loadLibrary("opencv_java3");
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

img = (ImageView) findViewById(R.id.imageView);

btn_original = (Button) findViewById(R.id.btn_original);
btn_grayscale = (Button) findViewById(R.id.btn_grayscale);
btn_histogram = (Button) findViewById(R.id.btn_histogram);
btn_resize = (Button) findViewById(R.id.btn_resize);
btn_threshold = (Button) findViewById(R.id.btn_threshold);

original = BitmapFactory.decodeResource(getResources(), R.drawable.sample);

btn_original.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
img.setImageBitmap(original);
}
});

btn_grayscale.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
/*grayscale = getGrayscale(original);
img.setImageBitmap(grayscale);*/
grayscale = BitmapFactory.decodeResource(getResources(), R.drawable.sample);

rgbMat = new Mat();
Utils.bitmapToMat(grayscale, rgbMat);

grayMat = new Mat(grayscale.getHeight(), grayscale.getWidth(),
CvType.CV_8U, new Scalar(1));
Imgproc.cvtColor(rgbMat, grayMat, Imgproc.COLOR_RGB2GRAY, 1);
Utils.matToBitmap(grayMat, grayscale);
img.setImageBitmap(grayscale);
Log.e("Width & Height:-", grayscale.getWidth() + "-" + grayscale.getHeight());
}
});

btn_histogram.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//histogram=HistogramEqualization.histogramEqualization(resize);

int lnth = grayscale.getByteCount();

ByteBuffer dst = ByteBuffer.allocate(lnth);
grayscale.copyPixelsToBuffer(dst);
byte[] byteArray = dst.array();

Log.e("byte array", byteArray + "");
Mat orgImage = new Mat();
orgImage.put(0, 0, byteArray);

Mat labImage = new Mat(grayscale.getHeight(), grayscale.getWidth(), CvType.CV_8UC1);
Imgproc.cvtColor(orgImage, labImage, Imgproc.COLOR_BGR2Lab);

CLAHE clahe = Imgproc.createCLAHE();
CLAHEmat = new Mat(grayscale.getHeight(), grayscale.getWidth(), CvType.CV_8UC1);
clahe.apply(labImage, CLAHEmat);

Utils.matToBitmap(CLAHEmat, histogram);
img.setImageBitmap(histogram);
}
});

btn_threshold.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.sheet);

Mat rgbMat = new Mat();
Utils.bitmapToMat(bmp, rgbMat);

Mat grayMat = new Mat(histogram.getHeight(), histogram.getWidth(),
CvType.CV_8U, new Scalar(1));
Imgproc.cvtColor(rgbMat, grayMat, Imgproc.COLOR_RGB2GRAY, 1);
Mat bwMat = new Mat();

Imgproc.cvtColor(rgbMat, grayMat, Imgproc.COLOR_RGB2GRAY);
Imgproc.equalizeHist(grayMat, grayMat);

Imgproc.threshold(grayMat, bwMat, 127.5, 255.0, Imgproc.THRESH_OTSU);
Utils.matToBitmap(bwMat, bmp);
Imgproc.createCLAHE();
img.setImageBitmap(bmp);
}
});
}
}