C# : how to validate/check if image is already exist in database?

I use the code shown to try to validate my image. Unfortunately, I failed to do that and this is the first time I'm doing a validation for image. Is there anything wrong in my logic? Did I forgot something here? What's the right way in doing these. I hope someone would be able to help me thank you

System.IO.FileNotFoundException: 'Could not find file 'C:\Users\Andrea\source\repos\CapstoneSIMS\CapstoneSIMS\bin\Debug\72EF99A3668CF13820B113EB2E090C37716C9742'.' (I'M getting these error when i tried to insert image)

NOTE: I'm saving the image as image not path and also the datatype is `Varbinary(MAX)` in my database

<pre lang="c#">
    public partial class ADDProduct : MetroForm
    {
        SIMSProduct _view;

        public ADDProduct(SIMSProduct _view)
        {
            InitializeComponent();
            this._view = _view;                  
        }

        DataSet ds = new DataSet();
        DataTable dt = new DataTable();
        byte[] photobyte;
        public string CalculateHash(string filename)
        {
            SHA1CryptoServiceProvider crypt = new SHA1CryptoServiceProvider();
            //MD5CryptoServiceProvider crypt = new MD5CryptoServiceProvider();
            string hash = string.Empty;
            using (FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read))
            {
                byte[] checksum = crypt.ComputeHash(fs);
                foreach (byte b in checksum)
                    hash += b.ToString("X2");
            }

            return (hash);
        }
    public static bool ImageExists(string filehash)
        {
            bool result = false;
            using (var connection = SQLConnection.GetConnection())
            {
                using (SqlCommand cmd = new SqlCommand("SELECT COUNT(0) FROM employee_product WHERE ImageHash = @ImageHash", connection))
                {
                    connection.Open();
                    int imagecount = (int)cmd.ExecuteScalar();
                    result = imagecount == 0;
                    connection.Close();
                }
            }

            return (result);
        }
        private void btn_add_Click(object sender, EventArgs e)
        {
            _view.ID = txt_id.Text;
            filehash = CalculateHash(@"C:\myimagefile.jpg");
            using (var con = SQLConnection.GetConnection())
            {
                if (string.IsNullOrEmpty(cbox_supplier.Text) || string.IsNullOrEmpty(txt_code.Text) || string.IsNullOrEmpty(txt_item.Text) || string.IsNullOrEmpty(txt_quantity.Text) || string.IsNullOrEmpty(txt_cost.Text) || pictureBox1.Image == null )
                {
                    CustomNotifcation.Show("Please input the required fields", CustomNotifcation.AlertType.warning);
                }
                else
                {          
                    ValidateCode.IsValidCode(txt_code,lbl_code,ds);
                    string filehash = CalculateHash(pictureBox1.Tag.ToString());

                    if (lbl_code.Visible == true)
                    {
                        CustomNotifcation.Show("CODE ALREADY EXIST", CustomNotifcation.AlertType.error);
                        lbl_code.Visible = false;                      
                    }
                    else if (ImageExists(pictureBox1.Tag.ToString()))
                    {
                        MessageBox.Show("image exists");
                        return;
                    }
                    else
                    {
                         using (var select = new SqlCommand("Insert into employee_product (Image, ImageHash, ID, Supplier, Codeitem, Itemdescription, Date, Quantity, Unitcost) Values (@Image, @ID, @Supplier, @Codeitem, @Itemdescription, @Date, @Quantity, @Unitcost)", con))
                            {                               
                                var ms = new MemoryStream();
                                pictureBox1.Image.Save(ms, pictureBox1.Image.RawFormat);
                                photobyte = ms.GetBuffer();
                                select.Parameters.Add("@Image", SqlDbType.VarBinary).Value = photobyte;
                                select.Parameters.Add("@ImageHash", SqlDbType.VarChar, 50);
                                select.Parameters["@ImageHash"].Value = filehash;
                                select.Parameters.Add("@Supplier", SqlDbType.VarChar).Value = cbox_supplier.Text;
                                select.Parameters.Add("@Codeitem", SqlDbType.VarChar).Value = txt_code.Text.Trim();
                                select.Parameters.Add("@Itemdescription", SqlDbType.VarChar).Value = txt_item.Text.Trim();
                                select.Parameters.Add("@Date", SqlDbType.VarChar).Value = date;
                                select.Parameters.Add("@Quantity", SqlDbType.Int).Value = txt_quantity.Text.Trim();
                                select.Parameters.Add("@Unitcost", SqlDbType.Int).Value = txt_cost.Text.Trim();
                                select.ExecuteNonQuery();
                                CustomMessage.Show("Message: Item successfully added!",CustomMessage.Messagetype.Success);
                                pictureBox1.Image = null;
                                cbox_supplier.Items.Clear();
                                txt_code.Clear();
                                txt_item.Clear();
                                txt_quantity.Clear();
                                txt_cost.Clear();
                                _view.btn_update.Enabled = false;
                                _view.AddingProduct();
                                this.Close();
                            }
                        }                
                    }                
                }
        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {
             var opnfd    = new OpenFileDialog();
            opnfd.Filter            = "Image Files (*.jpg;*.jpeg;.*.png;)|*.jpg;*.jpeg;.*.png;";
            opnfd.Title             = "Select Item";

            if (opnfd.ShowDialog() == DialogResult.OK)
            {
                pictureBox1.SizeMode    = PictureBoxSizeMode.StretchImage;
                pictureBox1.Image       = Image.FromFile(opnfd.FileName);
                CalculateHash(opnfd.FileName);
            }
        }
    }