private System.Drawing.Image ConvertirByteEnImage(byte[] img)
        {
            System.Drawing.Image nouvelleImage;
            MemoryStream ms = new MemoryStream(img, 0, img.Length);
            nouvelleImage = System.Drawing.Image.FromStream(ms, true);
            return nouvelleImage;
        }
        private byte[] ConvertirImageEnByte(System.Drawing.Image img, System.Drawing.Imaging.ImageFormat Format)
        {
            byte[] tmp;
            MemoryStream ms = new MemoryStream();
            img.Save(ms, Format);
            tmp = ms.ToArray();
            return tmp;
        }