C#绘制直方图中遇到问题

[Cathy129]

这个出来的直方图有问题



双击“histogram”控件，并在其中添加如下代码：
private void histogram_Click(object sender, EventArgs e)
{
if (curBitmap != null)
{
//定义并实例化新窗体，并把图像数据传递给它；
histForm histoGram = new histForm(curBitmap);
//打开从窗体；
histoGram.ShowDialog();
}
else
{
//没有打开图像时，弹出对应的提示框；
MessageBox.Show("请先打开图像！");
}
}

然后在打开的histForm窗体中先定义以下3个数据成员：
//图像数据
private System.Drawing.Bitmap bmpHist;
//为了标识横纵坐标的标识；
private int[] countPixel;

private int maxPixel=1000;//记录最大的灰度级个数
为了实现两个窗体之间的数据传递，需要改写histForm窗体的构造函数，其代码如下：
public histForm(Bitmap bmp)
{
InitializeComponent();
//把主窗体的图像数据传递给从窗体
bmpHist = bmp;
//灰度级计数
countPixel=new int[256];
}

分别为histForm窗体添加Paint和Load事件，Paint事件用于绘制直方图，Load事件用于计算各个灰度级所具有的像素个数，其代码如下：

1——————————————————————Paint事件；
private void histForm_Paint(object sender, PaintEventArgs e)
{
//获取Graphics对象
Graphics g = e.Graphics;

//创建一个宽度为1的黑色钢笔
Pen curPen = new Pen(Brushes.Black, 1);
//绘制坐标轴
//（y，x）=(50,240)原点；
g.DrawLine(curPen,50,240,320,240);//横坐标
g.DrawLine(curPen,50,240,50,30);//纵坐标
//绘制并标识坐标刻度
g.DrawLine(curPen, 100, 240, 100, 242);
g.DrawLine(curPen, 150, 240, 150, 242);
g.DrawLine(curPen, 200, 240, 200, 242);
g.DrawLine(curPen, 250, 240, 250, 242);
g.DrawLine(curPen, 300, 240, 300, 242);
g.DrawString("0", new Font("New Timer", 8), Brushes.Black, new PointF(46, 242));
g.DrawString("50", new Font("New Timer", 8), Brushes.Black, new PointF(92, 242));
g.DrawString("100", new Font("New Timer", 8), Brushes.Black, new PointF(139, 242));
g.DrawString("150", new Font("New Timer", 8), Brushes.Black, new PointF(189, 242));
g.DrawString("200", new Font("New Timer", 8), Brushes.Black, new PointF(239, 242));
g.DrawString("250", new Font("New Timer", 8), Brushes.Black, new PointF(289, 242));
g.DrawLine(curPen,48,40,50,40);
g.DrawString(maxPixel.ToString(), new Font("New Timer", 8), Brushes.Black, new PointF(18, 38));
//开始绘制直方图
double temp = 0;
for (int i = 0; i < 256;i++ )
{
//计算出纵坐标的长度
temp = 200.0 * countPixel[i] / maxPixel;
g.DrawLine(curPen,50+i,240,50+i,240-(int)temp);
}
//释放对象
curPen.Dispose();
}
2————————————————Load事件：

/// <summary>
/// 直方图的绘制；
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void histForm_Load(object sender, EventArgs e)
{
//锁定8位灰度位图
Rectangle rect = new Rectangle(0, 0, bmpHist.Width, bmpHist.Height);
System.Drawing.Imaging.BitmapData bmpData = bmpHist.LockBits(rect,
System.Drawing.Imaging.ImageLockMode.ReadOnly,
bmpHist.PixelFormat);
IntPtr ptr = bmpData.Scan0;
int bytes = bmpHist.Width * bmpHist.Height;
byte[] graybValues = new byte[bytes];
System.Runtime.InteropServices.Marshal.Copy(ptr, graybValues, 0, bytes);
byte temp = 0;
maxPixel = 0;
//灰度等级数组清零
Array.Clear(countPixel,0,256);
//计算各个灰度级的像素个数
for (int i = 0; i < bytes;i++ )
{
//灰度级
temp=graybValues[i];
//计数加1
countPixel[temp]++;
if(countPixel[temp]>maxPixel)
{
//找到灰度频率最大的像素数，用于绘制直方图
maxPixel=countPixel[temp];
}
}
//解锁
System.Runtime.InteropServices.Marshal.Copy(graybValues,0,ptr,bytes);
bmpHist.UnlockBits(bmpData);
}

[Cathy129]

求大神改错啊！！！