CaptchaRecogition.ImageProcess.GetImgBoundaryList C# (CSharp) Метод

        public static List<Boundary> GetImgBoundaryList(Image img, ref Bitmap _bmp, bool is4Chars,int charWidth=10)
        {
            List<Boundary> list = new List<Boundary>();
            Bitmap bmp = new Bitmap(img);
            int startY = 0;
            int endY = 0;
            int startX = 0;
            int endX = 0;
            try
            {
                for (int i = 0; i < 10; i++)
                {
                    startY = GetStartBoundaryY(img, startY);
                    if (startY >= 0)
                    {
                        endY = GetEndBoundaryY(img, startY + 1);
                        //标记
                        startX = GetStartBoundaryX(img, startY, endY);
                        int _startX = startX;
                        bool flag = false;
                        while (!flag && _startX < img.Height)
                        {
                            endX = GetEndBoundaryX(img, _startX, startY, endY);
                            flag = endX - _startX >=5;//最小高度
                            _startX = _startX + 1;
                        }
                        if (endX > 0 && endX - startX >= 5)//最小高度
                        {
                            list.Add(new Boundary { EndY = endY, EndX = endX, StartY = startY, StartX = startX });
                        }
                        startY = endY;
                    }
                    else
                    {
                        break;
                    }
                }
                if (is4Chars&&list.Count!=4)
                {
                    list = NotFourChars(img, out _bmp, list,charWidth);
                }
                else
                {
                    _bmp = bmp;
                }
                List<Boundary> tempBdList = list;
                for (int i = 0; i < tempBdList.Count; i++)
                {
                    if (
                        !((tempBdList[i].EndY - tempBdList[i].StartY >= charWidth) &&//最小宽度比较
                          (tempBdList[i].EndX - tempBdList[i].StartX >= 5)))//最小高度
                    {
                        list.Remove(tempBdList[i]);
                    }
                }
            }
            catch (Exception ex)
            {
                throw;
            }
            return list;
        }
        /// <summary>