How to implement Retinex theory in Android with Opencv

Question

I want to implement Retinx theory for improvement illumination,in this question, I found steps for implement :

Retinex algorithm implementation

and I write code for Android but in that section, I marked with "?" compiler give me an error when I passed "Mat retinex" plz help me, guys.

    Mat mRgba,imgGray,imgCanny,imgYuv;
    Mat gaussianFtr;
    Mat retinx;
    Mat retinxTotal;

    mRgba=new Mat(height,width, CvType.CV_8UC4);
    imgGray=new Mat(height,width, CvType.CV_8UC1);
    imgCanny=new Mat(height,width, CvType.CV_8UC1);
    imgYuv=new Mat(height,width, CvType.CV_8UC3);
    gaussianFtr=new Mat();
    retinx=new Mat();
    retinxTotal=new Mat();

 public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)      {
      mRgba=inputFrame.rgba();
     Imgproc.cvtColor(mRgba,imgYuv,Imgproc.COLOR_RGB2YUV);
     Imgproc.GaussianBlur(imgYuv, gaussianFtr,new Size(45,45),0);
     retinxTotal=255*(Math.log10(?))+127.5;

       return gaussianFtr;
       }
  }