灰度直方图是灰度的函数，描述的是图像中具有该灰度级的像素的个数。如果用直角坐标系来表示，则它的横坐标是灰度级，纵坐标是该灰度出现的概率（像素的个数）。
灰度直方图的分布函数：
其中，K是指第k个灰度级，如果是8位灰度图像，k=0、1、……、255。
处理图像生成直方图数据
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//将图像数据复制到byte中Rectangle rect = new
Rectangle(0, 0, bmpHist.Width, bmpHist.Height);
System.Drawing.Imaging.BitmapData bmpdata = bmpHist.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, bmpHist.PixelFormat);IntPtr ptr = bmpdata.Scan0;int
bytes = bmpHist.Width * bmpHist.Height * 3;
byte[] grayValues = new
byte[bytes];
System.Runtime.InteropServices.Marshal.Copy(ptr, grayValues, 0, bytes);//统计直方图信息byte
temp = 0;
maxPixel = 0;Array.Clear(countPixel, 0, 256);for
(int
i = 0; i < bytes; i++)
{ temp = grayValues[i];
countPixel[temp]++;
if
(countPixel[temp] > maxPixel)
{
maxPixel = countPixel[temp];
}
}System.Runtime.InteropServices.Marshal.Copy(grayValues, 0, ptr, bytes);bmpHist.UnlockBits(bmpdata); |
绘制直方图信息
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//画出坐标系Graphics g = e.Graphics;Pen curPen = new
Pen(Brushes.Black, 1);
g.DrawLine(curPen, 50, 240, 320, 240);g.DrawLine(curPen, 50, 240, 50, 30);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("0", new
Font("New Timer", 8), Brushes.Black, new
PointF(34, 234));
g.DrawString(maxPixel.ToString(), new
Font("New Timer", 8), Brushes.Black, new
PointF(18, 34));
double
temp = 0;
for
(int
i = 0; i < 256; i++)
{ temp = 200.0 * countPixel[i] / maxPixel;
g.DrawLine(curPen, 50 + i, 240, 50 + i, 240 - (int)temp);
}curPen.Dispose(); |
全局变量定义及赋值
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private
System.Drawing.Bitmap bmpHist;
private
int[] countPixel;
private
int
maxPixel;
public
Grey_ScaleMapForm(Bitmap bmp)
{ InitializeComponent();
bmpHist = bmp;
countPixel = new
int[256];
} |
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