public Bitmap PgmToBitmap(PgmImage pgmImage)
        {
            if (pgmImage != null && pgmImage.MagicNumber == "P2")
            {
                int    width  = pgmImage.Width;
                int    height = pgmImage.Height;
                Bitmap result = new Bitmap(width, height);

                Graphics gr = Graphics.FromImage(result);

                int pixel = 0;
                for (int i = 0; i < pgmImage.Height; ++i)
                {
                    for (int j = 0; j < pgmImage.Width; ++j)
                    {
                        int        pixelColor = pgmImage.Data[pixel++];
                        Color      c          = Color.FromArgb(pixelColor, pixelColor, pixelColor);
                        SolidBrush sb         = new SolidBrush(c);
                        gr.FillRectangle(sb, j, i, 1, 1);
                    }
                }

                return(result);
            }
            return(null);
        }
        private void openToolStripMenuItem_Click(object sender, EventArgs e)
        {
            DialogResult dlgResult = openFileDialog1.ShowDialog();

            if (dlgResult == DialogResult.OK)
            {
                try {
                    pgmOriginalImage = new PgmImage(openFileDialog1.FileName);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
                pictureBoxOriginalImage.Image = PgmToBitmap(pgmOriginalImage);

                if (pictureBoxOriginalImage.Image != null)
                {
                    inputFileName = openFileDialog1.FileName;

                    trackBarThreshold.Maximum = pgmOriginalImage.MaxVal;
                    trackBarThreshold.Value   = trackBarThreshold.Minimum;
                    trackBarThreshold.Enabled = true;

                    outputFileName = null;
                    pictureBoxResultImage.Visible = true;
                    pictureBoxResultImage.Image   = null;

                    labelMagicNumber.Text = "Magic Number: " + pgmOriginalImage.MagicNumber;
                    labelWidth.Text       = "Width: " + pgmOriginalImage.Width + " px";
                    labelHieght.Text      = "Height: " + pgmOriginalImage.Height + " px";
                    labelMaxVal.Text      = "Maximum Gray Value: " + pgmOriginalImage.MaxVal;
                }
                else
                {
                    inputFileName  = null;
                    outputFileName = null;
                    pictureBoxResultImage.Visible = false;

                    pictureBoxOriginalImage.Image = pictureBoxOriginalImage.ErrorImage;
                    trackBarThreshold.Value       = trackBarThreshold.Minimum;
                    trackBarThreshold.Enabled     = false;

                    labelMagicNumber.Text = "Magic Number:";
                    labelWidth.Text       = "Width:";
                    labelHieght.Text      = "Height:";
                    labelMaxVal.Text      = "Maximum Gray Value:";
                    labelThreshold.Text   = "Threshold:";
                }
            }
        }
        public PgmImage BitmapToPgm(Bitmap monoBmpImage, string magicNumber)
        {
            if (monoBmpImage != null)
            {
                PgmImage result = new PgmImage(monoBmpImage.Width, monoBmpImage.Height, magicNumber, null, 255);
                int      pixel  = 0;
                for (int i = 0; i < monoBmpImage.Height; ++i)
                {
                    for (int j = 0; j < monoBmpImage.Width; ++j)
                    {
                        // the image is monochromatic
                        result.Data[pixel++] = monoBmpImage.GetPixel(j, i).R;
                    }
                }

                return(result);
            }

            return(null);
        }