private string GetContentType(ConvertImageFileType convertImageFileType)
        {
            string contentType;

            switch (convertImageFileType)
            {
            case ConvertImageFileType.JPG:
                contentType = "image/jpeg";
                break;

            case ConvertImageFileType.BMP:
                contentType = "image/bmp";
                break;

            case ConvertImageFileType.PNG:
                contentType = "image/png";;
                break;

            default:
                throw new ArgumentOutOfRangeException();
            }

            return(contentType);
        }
        public static string GetMimeType(ConvertImageFileType convertImageFileType)
        {
            string contentType;
            switch (convertImageFileType)
            {
                case ConvertImageFileType.JPG:
                    contentType = "image/jpeg";
                    break;
                case ConvertImageFileType.BMP:
                    contentType = "image/bmp";
                    break;
                case ConvertImageFileType.PNG:
                    contentType = "image/png"; ;
                    break;
                default:
                    throw new ArgumentOutOfRangeException();
            }

            return contentType;
        }