public void yap(string sourcePath,string destinationPath)

        {

            Bitmap myBitmap = new Bitmap(sourcePath);

            const float limit = 0.1f;

            //const float limit = 0.3f;

            for (int i = 0; i < myBitmap.Width; i++)

            {

                for (int j = 0; j < myBitmap.Height; j++)

                {

                    Color c = myBitmap.GetPixel(i, j);

                    if (c.GetBrightness() > limit)

                    {

                        myBitmap.SetPixel(i, j, Color.White);

                    }

                }

            }

            myBitmap.Save(destinationPath);

        }