C#绘制数字图像灰度直方图 |
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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 //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 //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 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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