C ＃ QR code generation and recognition, removing white edges and any color

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using ZXing;

namespace QRCode
{
    public partial class frmMain : Form
    {
        public frmMain()
        {
            InitializeComponent();
        }


        private void btnQRCode_Click(object sender, EventArgs e)
        {
            string content = txtInputForQR.Text;

            Dictionary<EncodeHintType, Object> hints = new Dictionary<EncodeHintType, object>();
            hints.Add(EncodeHintType.ERROR_CORRECTION, ZXing.QrCode.Internal.ErrorCorrectionLevel.H);
            hints.Add(EncodeHintType.CHARACTER_SET, "UTF-8"); // code  
            MultiFormatWriter writer = new MultiFormatWriter();

            ZXing.Common.BitMatrix bm = writer.encode(content, ZXing.BarcodeFormat.QR_CODE, 300, 300, hints);
            BarcodeWriter barcodeWriter = new BarcodeWriter();
            //barcodeWriter.Renderer = new ZXing.Rendering.BitmapRenderer
            //{
            //    Background = Color.FromArgb(242, 241, 250),
            //    Foreground = Color.FromArgb(46, 51, 57)
            //};

            barcodeWriter.Renderer = new ZXing.Rendering.BitmapRenderer
            {
                Background = Color.White,
                Foreground = Color.Green
            };

            System.Drawing.Bitmap bmp = RemoveWhiteMargin(bm, barcodeWriter.Write(bm));// Remove edges                                                                             

            pictureBox1.Image = bmp;
        }

        private static Bitmap RemoveWhiteMargin(ZXing.Common.BitMatrix bitMatrix, Bitmap bitmap)
        {
            // To obtain parameters 
            int[] rec = bitMatrix.getEnclosingRectangle();
            int left = rec[0];
            int top = rec[1];
            int width = rec[2];
            int height = rec[3];
            Bitmap newImg = new Bitmap(width, height);
            Graphics g = Graphics.FromImage(newImg);
            // Intercept 
            g.DrawImage(bitmap, 0, 0, new Rectangle(left, top, newImg.Width, newImg.Height), GraphicsUnit.Pixel);
            return newImg;
        }

        private void btnQRDeCode_Click(object sender, EventArgs e)
        {

            OpenFileDialog openFileDialog1 = new OpenFileDialog();
            openFileDialog1.Filter = " image file (*.jpg;*.jpeg;*.gif;*.bmp;*.png)|*.jpg;*.jpeg;*.gif;*.bmp;*.png";

            if (openFileDialog1.ShowDialog() != DialogResult.OK)
            {
                return;
            }
            Image img = null;
            try
            {
                img = Image.FromFile(openFileDialog1.FileName);
                pictureBox1.Image = img;
            }
            catch (Exception ex)
            {
                MessageBox.Show(" The file format is not correct " + ex.Message);
            }
            BarcodeReader reader = new BarcodeReader();
            reader.Options.CharacterSet = "UTF-8";
            Result result = null;
            try
            {
                result = reader.Decode(new Bitmap(img));
            }
            catch (Exception ex)
            {

                txtInputForQR.Text = " Identify anomalies " + ex.Message;
            }

            if (result != null)
            {
                txtOutputForQR.Text = result.Text;
            }
            else
            {
                txtOutputForQR.Text = " Unrecognized information ！";
            }
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            SaveFileDialog sFD = new SaveFileDialog();
            sFD.Filter = " Save the picture (*.png) |*.png| All the files (*.*) |*.*";
            sFD.DefaultExt = "*.png|*.png";
            sFD.AddExtension = true;
            if (sFD.ShowDialog() == DialogResult.OK)
            {
                if (sFD.FileName != "")
                {
                    Bitmap bitmap = (Bitmap)pictureBox1.Image;
                    bitmap.Save(sFD.FileName, System.Drawing.Imaging.ImageFormat.Png);
                }

            }
        }
    }
}

Demo download