C# 在null c中从有效对象到位图的转换#

我试图使用线程来处理多个相互平行的图像。在代码中，您将看到我为“imgprocessing”方法提供了一个位图，但图像处理只接收对象参数。所以我必须键入cast-to-bitmap，在某个点它抛出异常：“参数无效”。显然，bitmap在某个点变为null。 只有在几个线程已经完成处理之后，才会发生这种情况。 问题是：为什么在类型转换期间我的位图为空？我不知道为什么它会停止正常转换。 代码- 主要内容：

IMG处理功能：

private static void imgProcessing(Object obj1)
        {
            Bitmap bt = new Bitmap((Image)obj1); //exception occurs here
            //Bitmap //ft = new Bitmap(bt);
            Color color = new Color();
            Ipn[] Iparams = new Ipn[6];
            int nm = 2211840;
            int i = 0;
            int j = 0;
            int k = 0;
            //int holder = 0;
            float hue = 0;
            float brt = 0;
            float sat = 0;
            GiveId(Iparams);

                for (i = 0; i < bt.Height; i++)
                {
                    for (j = 0; j < bt.Width; j++)
                    {
                        color = bt.GetPixel(j, i);
                        hue = color.GetHue();
                        sat = color.GetSaturation();
                        brt = color.GetBrightness();
                        #region if statements
                        //white
                        if (brt > 0.7)
                        {
                            Iparams[5].Percent++;
                            //ft.SetPixel(j,i,Color.White);
                        }

                        //gray
                        else if (sat <= 0.25)
                        {
                            Iparams[4].Percent++;
                            //ft.SetPixel(j, i, Color.Gray);
                        }
                        //black
                        else if (color.R <= 15 && color.G <= 15 && color.B <= 15 && brt < 0.3)
                        {
                            Iparams[3].Percent++;
                            //ft.SetPixel(j, i, Color.Black);
                        } 

                        //red
                        else if (hue > 0 && hue <= 59)
                        {
                            Iparams[0].Percent++;
                            //ft.SetPixel(j, i, Color.Red);
                        }
                        //green 
                        else if (hue > 60 && hue <= 150)
                        {
                            Iparams[1].Percent++;
                            //ft.SetPixel(j, i, Color.Green);
                        }

                        //blue
                        else if (hue > 150 && hue <= 270)
                        {
                            Iparams[2].Percent++;
                            //ft.SetPixel(j, i, Color.Blue);
                        }
                        #endregion
                    }
                }


                for (k = 0; k < Iparams.Length; k++)
                {
                    Iparams[k].Percent = ((float)Iparams[k].Percent / nm) * 100;
                }

                //bubblesort(Iparams);

                lock (lockobject)
                {
                    #region space code
                    //calculate the color percentages for each color

                    //if (Iparams[0].ID == ID.gray && Iparams[1].ID == ID.blue)
                    //{
                    //    counter2++;
                    //}
                    //else if (Iparams[1].ID == ID.white && Iparams[0].ID == ID.blue)
                    //{
                    //    counter1++;
                    //}
                    #endregion

                    #region ocean code
                    //if (Iparams[0].ID == ID.blue)
                    //{
                    //    Interlocked.Increment(ref counter1);
                    //}
                    //else
                    //    Interlocked.Increment(ref counter2);

                    //holder = (int)(Iparams[0].Percent - Iparams[1].Percent);
                    //Interlocked.Add(ref dis, holder);
                    #endregion

                    ////ft.Save(@"C:\Users\User\Desktop\results\" + name + ".jpg");
                    //Interlocked.Increment(ref name);
                    #region veg code
                    //if (Iparams[0].ID == ID.green)
                    //{
                    //    Interlocked.Increment(ref counter1);
                    //    holder = (int)(Iparams[0].Percent - Iparams[1].Percent);
                    //    Interlocked.Add(ref dis, holder);
                    //}
                    //else
                    //    Interlocked.Increment(ref counter2);
                    #endregion 
                    #region snow&clouds code
                    /*understanding what is the highest percentages of white and gray and the lowest.
                     * 
                     */
                    double graypercent = Convert.ToDouble(Iparams[4].Percent);
                    double whitepercent = Convert.ToDouble(Iparams[5].Percent);
                    if(Iparams[4].Percent > maxgray)
                    {
                        Interlocked.Exchange(ref maxgray, graypercent);
                    }
                    else if(Iparams[4].Percent < mingray)
                    {
                        Interlocked.Exchange(ref mingray, graypercent);
                    }

                    if(Iparams[5].Percent > maxwhite)
                    {
                        Interlocked.Exchange(ref maxwhite, Iparams[5].Percent);
                    }
                    else if(Iparams[5].Percent < minwhite)
                    {
                        Interlocked.Exchange(ref minwhite, Iparams[5].Percent);
                    }
                    #endregion 

                }

私有静态无效imgProcessing（对象obj1）
{
位图bt=新位图（（图像）obj1）；//此处发生异常
//位图//英尺=新位图（bt）；
颜色=新颜色（）；
Ipn[]IPARMS=新Ipn[6]；
int nm=2211840；
int i=0；
int j=0；
int k=0；
//int holder=0；
浮动色调=0；
浮动brt=0；
浮动sat=0；
GiveId（ipaams）；
对于（i=0；i0.7）
{
iParms[5]。百分比++；
//ft.SetPixel（j，i，颜色.白色）；
}
//灰色的
否则如果（sat）您能否简化您的示例，使其能够在本地实际重现问题？例如，如果您在错误行之后从imgProcessing方法中删除所有代码，您仍然能够重现问题？如果您不从磁盘加载位图，而是动态创建一组位图，会发生什么情况文件为空？位图（字符串）构造函数仅为未找到的文件指定了一个异常。顺便说一句，我相信您有一个瓶颈。位图（字符串）构造函数阻塞I/O，所以您一次只读取一个文件，等待I/O，启动一个线程，然后继续循环的下一个迭代。为什么不将文件名传递给线程，让线程启动I/O，这样循环就不会阻塞？chris rollins-感谢您对瓶颈的提醒，但我没有告诉您完全理解“I/O块”的含义。如果我传递线程文件名并在imgprocessing中创建位图，这不是因为读取冲突吗？只有当他们试图读取相同的文件时才应该是问题。但是，如果我记得正确，GDI（System.Drawing使用的）无论如何，不允许多个线程在同一位图对象上读/写。
private static void imgProcessing(Object obj1)
        {
            Bitmap bt = new Bitmap((Image)obj1); //exception occurs here
            //Bitmap //ft = new Bitmap(bt);
            Color color = new Color();
            Ipn[] Iparams = new Ipn[6];
            int nm = 2211840;
            int i = 0;
            int j = 0;
            int k = 0;
            //int holder = 0;
            float hue = 0;
            float brt = 0;
            float sat = 0;
            GiveId(Iparams);

                for (i = 0; i < bt.Height; i++)
                {
                    for (j = 0; j < bt.Width; j++)
                    {
                        color = bt.GetPixel(j, i);
                        hue = color.GetHue();
                        sat = color.GetSaturation();
                        brt = color.GetBrightness();
                        #region if statements
                        //white
                        if (brt > 0.7)
                        {
                            Iparams[5].Percent++;
                            //ft.SetPixel(j,i,Color.White);
                        }

                        //gray
                        else if (sat <= 0.25)
                        {
                            Iparams[4].Percent++;
                            //ft.SetPixel(j, i, Color.Gray);
                        }
                        //black
                        else if (color.R <= 15 && color.G <= 15 && color.B <= 15 && brt < 0.3)
                        {
                            Iparams[3].Percent++;
                            //ft.SetPixel(j, i, Color.Black);
                        } 

                        //red
                        else if (hue > 0 && hue <= 59)
                        {
                            Iparams[0].Percent++;
                            //ft.SetPixel(j, i, Color.Red);
                        }
                        //green 
                        else if (hue > 60 && hue <= 150)
                        {
                            Iparams[1].Percent++;
                            //ft.SetPixel(j, i, Color.Green);
                        }

                        //blue
                        else if (hue > 150 && hue <= 270)
                        {
                            Iparams[2].Percent++;
                            //ft.SetPixel(j, i, Color.Blue);
                        }
                        #endregion
                    }
                }


                for (k = 0; k < Iparams.Length; k++)
                {
                    Iparams[k].Percent = ((float)Iparams[k].Percent / nm) * 100;
                }

                //bubblesort(Iparams);

                lock (lockobject)
                {
                    #region space code
                    //calculate the color percentages for each color

                    //if (Iparams[0].ID == ID.gray && Iparams[1].ID == ID.blue)
                    //{
                    //    counter2++;
                    //}
                    //else if (Iparams[1].ID == ID.white && Iparams[0].ID == ID.blue)
                    //{
                    //    counter1++;
                    //}
                    #endregion

                    #region ocean code
                    //if (Iparams[0].ID == ID.blue)
                    //{
                    //    Interlocked.Increment(ref counter1);
                    //}
                    //else
                    //    Interlocked.Increment(ref counter2);

                    //holder = (int)(Iparams[0].Percent - Iparams[1].Percent);
                    //Interlocked.Add(ref dis, holder);
                    #endregion

                    ////ft.Save(@"C:\Users\User\Desktop\results\" + name + ".jpg");
                    //Interlocked.Increment(ref name);
                    #region veg code
                    //if (Iparams[0].ID == ID.green)
                    //{
                    //    Interlocked.Increment(ref counter1);
                    //    holder = (int)(Iparams[0].Percent - Iparams[1].Percent);
                    //    Interlocked.Add(ref dis, holder);
                    //}
                    //else
                    //    Interlocked.Increment(ref counter2);
                    #endregion 
                    #region snow&clouds code
                    /*understanding what is the highest percentages of white and gray and the lowest.
                     * 
                     */
                    double graypercent = Convert.ToDouble(Iparams[4].Percent);
                    double whitepercent = Convert.ToDouble(Iparams[5].Percent);
                    if(Iparams[4].Percent > maxgray)
                    {
                        Interlocked.Exchange(ref maxgray, graypercent);
                    }
                    else if(Iparams[4].Percent < mingray)
                    {
                        Interlocked.Exchange(ref mingray, graypercent);
                    }

                    if(Iparams[5].Percent > maxwhite)
                    {
                        Interlocked.Exchange(ref maxwhite, Iparams[5].Percent);
                    }
                    else if(Iparams[5].Percent < minwhite)
                    {
                        Interlocked.Exchange(ref minwhite, Iparams[5].Percent);
                    }
                    #endregion 

                }