“所有致我于死地的，也激发我胆魄”，姚贝娜的《心火》，是我近年来听过最好的歌，特此推荐一下。
图像处理，大概分三步：1.LockBits()；2.进行处理；3.UnlockBits()；这比起 C++ 来，不知清爽几许？
编程，是为了满足人的需求，所以进行灰度处理时，不是简单的 (r + g + b) / 3，而是分别乘以合适的比例值，r * 0.30 + g * 0.59 + b * 0.11。这是因为人眼对 green 最敏感，red 次之，blue 最低。
只实现了灰度处理，边缘提取，二值化，缩小，Rotate 等有限功能，代码不言自明，无需多说。
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text; namespace x01.Utilities
{
public static class BitmapHelper
{
/// <summary>
/// 对 bitmap 进行灰度处理。r,g,b 权重相加为 1。
/// </summary>
/// <param name="bmp">所要处理的 bitmap 对象。</param>
/// <param name="rWeight">red 权重。</param>
/// <param name="gWeight">green 权重。</param>
/// <param name="bWeight">blue 权重。</param>
public static void Gray(Bitmap bmp, float rWeight = 0.30f, float gWeight = 0.59f, float bWeight = 0.11f)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length);
for (int y = ; y < bmp.Height * data.Stride; y += data.Stride)
{
for (int x = ; x < bmp.Width * ; x += )
{
int i = y + x;
byte b = buf[i];
byte g = buf[i + ];
byte r = buf[i + ];
buf[i] = buf[i + ] = buf[i + ] = (byte)(b * bWeight + g * gWeight + r * rWeight);
}
}
Marshal.Copy(buf, , data.Scan0, buf.Length);
bmp.UnlockBits(data);
} /// <summary>
/// 对 bitmap 进行中值滤波处理。
/// </summary>
/// <param name="bmp">所要处理的 bitmap 对象。</param>
public static void MedianFilter(Bitmap bmp)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
unsafe
{
byte* pBuf = (byte*)data.Scan0.ToPointer();
for (int i = ; i < bmp.Height - ; i++)
{
for (int j = ; j < bmp.Width - ; j++)
{
List<byte>[] list = new List<byte>[];
for (int k = ; k < ; k++)
{
list[k] = new List<byte>();
} for (int y = -; y < ; y++)
{
for (int x = -; x < ; x++)
{
int index = (i + y) * data.Stride + (j + x) * ;
for (int k = ; k < ; k++)
{
list[k].Add(pBuf[index + k]);
}
}
} for (int k = ; k < ; k++)
{
list[k].Sort();
} int indexMedian = i * data.Stride + j * ; for (int k = ; k < ; k++)
{
pBuf[indexMedian + k] = list[k][]; // 4: median value after sort.
list[k].Clear();
} list = null;
}
}
} bmp.UnlockBits(data);
} /// <summary>
/// 获取 bitmap 所选的颜色分量直方图。
/// </summary>
/// <param name="bmp">所要处理的 bitmap 对象</param>
/// <param name="bgrOffset">所选的颜色： blue=0, green=1, red=2</param>
/// <returns>返回 256 * 256 大小的 Bitmap 直方图。</returns>
public static Bitmap Histogram(Bitmap bmp, int bgrOffset = )
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); int[] countColors = new int[];
for (int y = ; y < bmp.Height; y++)
{
for (int x = ; x < bmp.Width; x++)
{
int index = y * data.Stride + x * ;
countColors[buf[index + bgrOffset]]++;
}
} bmp.UnlockBits(data); int maxIndex = ;
for (int i = ; i < ; i++)
{
if (countColors[maxIndex] < countColors[i])
{
maxIndex = i;
}
} Bitmap hist = new Bitmap(, );
Graphics g = Graphics.FromImage(hist);
g.Clear(Color.Wheat);
for (int i = ; i < ; i++)
{
int h = * countColors[i] / countColors[maxIndex];
g.DrawLine(new Pen(Color.FromArgb(i, i, i), 1f), i, , i, - h); // top bottom inverse
} return hist;
} public static void ExtractEdge(Bitmap bmp)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
byte[] edge = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); for (int y = ; y < bmp.Height - ; y++)
{
for (int x = ; x < bmp.Width - ; x++)
{
int index = y * data.Stride + x * ;
byte gray = (byte)((buf[index] + buf[index + ] + buf[index + ]) / ); int value = ;
for (int i = -; i < ; i++) // neareat eight point
{
for (int j = -; j < ; j++)
{
if (i == && j == )
{
continue;
} int index2 = (y + i) * data.Stride + (x + i) * ;
byte gray2 = (byte)((buf[index2] + buf[index2 + ] + buf[index2 + ]) / );
value += Math.Abs(gray - gray2);
}
} edge[index] = edge[index + ] = edge[index + ] = (byte)(value >> );
}
} Marshal.Copy(edge, , data.Scan0, edge.Length);
bmp.UnlockBits(data);
} /// <summary>
/// 对图像进行二值化处理。
/// </summary>
/// <param name="bmp">处理的图像。</param>
/// <param name="minValue">最小阀值。</param>
/// <param name="maxValue">最大阀值。</param>
public static void Binary(Bitmap bmp, int minValue, int maxValue)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); for (int y = ; y < bmp.Height; y++)
{
for (int x = ; x < bmp.Width; x++)
{
int index = y * data.Stride + x * ;
int gray = (buf[index] + buf[index+] +buf[index+])/;
if (gray >= minValue && gray <= maxValue)
{
buf[index] = buf[index + ] = buf[index + ] = ;
}
else
{
buf[index] = buf[index + ] = buf[index + ] = ;
}
}
} Marshal.Copy(buf, , data.Scan0, buf.Length);
bmp.UnlockBits(data);
} /// <summary>
/// 对灰度图像进行对比度增强。
/// </summary>
/// <param name="bmp">灰度图像</param>
/// <param name="srcMin">原灰度下界</param>
/// <param name="srcMax">原灰度上界</param>
/// <param name="destMin">目标灰度下界</param>
/// <param name="destMax">目标灰度上界</param>
public static void Enhance(Bitmap bmp, int srcMin, int srcMax, int destMin, int destMax)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); for (int y = ; y < bmp.Height; y++)
{
for (int x = ; x < bmp.Width; x++)
{
int index = y * data.Stride + x * ;
int gray = (buf[index] + buf[index + ] + buf[index + ]) / ;
float value = (float)(destMax - destMin) / (srcMax - srcMin) * (gray - srcMin) + destMin;
buf[index] = buf[index + ] = buf[index + ] =
value < byte.MinValue ? byte.MinValue : (value > byte.MaxValue ? byte.MaxValue : (byte)value);
}
} Marshal.Copy(buf, , data.Scan0, buf.Length); bmp.UnlockBits(data);
} public static void Enhance(Bitmap bmp, float n)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); for (int y = ; y < bmp.Height; y++)
{
for (int x = ; x < bmp.Width; x++)
{
int index = y * data.Stride + x * ;
int gray = (buf[index] + buf[index + ] + buf[index + ]) / ;
float value = gray * n;
buf[index] = buf[index + ] = buf[index + ] =
value < byte.MinValue ? byte.MinValue : (value > byte.MaxValue ? byte.MaxValue : (byte)value);
}
} Marshal.Copy(buf, , data.Scan0, buf.Length);
bmp.UnlockBits(data);
} public static void ConnectRegion(Bitmap bmp)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); int sign = ;
for (int y = ; y < bmp.Height; y++)
{
for (int x = ; x < bmp.Width; x++)
{
int index = y * data.Stride + x * ;
if (buf[index] == )
{
SignRegion(buf, x * , y * data.Stride, sign, data.Stride, bmp.Width, bmp.Height);
sign += ;
}
}
} Marshal.Copy(buf, , data.Scan0, buf.Length);
bmp.UnlockBits(data);
} public static void SignRegion(byte[] buf, int x, int y, int sign, int stride, int width, int height)
{
int index = x + y;
buf[index] = buf[index + ] = buf[index + ] = (byte)sign; if (x > && buf[index -] == ) // left
{
SignRegion(buf, x - , y, sign, stride, width, height);
} if (x < width * - && buf[index + ] == ) // right
{
SignRegion(buf, x + , y, sign, stride, width, height);
} if (y > && buf[index - stride] == ) // top
{
SignRegion(buf, x, y - stride, sign, stride, width, height);
} if (y < height * stride && buf[index + stride] == ) // bottom
{
SignRegion(buf, x, y + stride, sign, stride, width, height);
} } /// <summary>
/// 缩小图像。
/// </summary>
/// <param name="bmp">图像</param>
/// <param name="widthFactor">宽度缩小倍数</param>
/// <param name="heightFactor">高度缩小倍数</param>
public static void Dilation(Bitmap bmp, float widthFactor, float heightFactor)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); byte[] result = new byte[data.Stride * bmp.Height];
for (int y = ; y < bmp.Height; y++)
{
for (int x = ; x < bmp.Width; x++)
{
int index = y * data.Stride + x * ; int rx = (int)(x * widthFactor);
int ry = (int)(y * heightFactor);
if (rx < || rx >= bmp.Width || ry < || ry >= bmp.Height)
{
continue;
}
int rindex = ry * data.Stride + rx * ; result[index] = buf[rindex];
result[index + ] = buf[rindex + ];
result[index + ] = buf[rindex + ];
}
} Marshal.Copy(result, , data.Scan0, result.Length);
bmp.UnlockBits(data);
} public static void Translate(Bitmap bmp, int xOffset, int yOffset)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); byte[] result = new byte[data.Stride * bmp.Height];
for (int y = ; y < bmp.Height; y++)
{
for (int x = ; x < bmp.Width; x++)
{
int index = y * data.Stride + x * ; int rx = x - xOffset;
int ry = y - yOffset;
if (rx < || rx >= bmp.Width || ry < || ry >= bmp.Height)
{
continue;
}
int rindex = ry * data.Stride + rx * ; result[index] = buf[rindex];
result[index + ] = buf[rindex + ];
result[index + ] = buf[rindex + ];
}
} Marshal.Copy(result, , data.Scan0, result.Length);
bmp.UnlockBits(data);
} public static void Rotate(Bitmap bmp, float angle, Point center)
{
BitmapData data = bmp.LockBits(new Rectangle(new Point(), bmp.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte[] buf = new byte[data.Stride * bmp.Height];
Marshal.Copy(data.Scan0, buf, , buf.Length); byte[] result = new byte[data.Stride * bmp.Height];
for (int y = ; y < bmp.Height; y++)
{
for (int x = ; x < bmp.Width; x++)
{
int index = y * data.Stride + x * ; int rx = (int)( (x - center.X) * Math.Cos(angle * Math.PI / )
- (y - center.Y) * Math.Sin(angle * Math.PI / ) + center.X );
int ry = (int)( (x - center.X) * Math.Sin(angle * Math.PI / )
+ (y - center.Y) * Math.Cos(angle * Math.PI / ) + center.Y ); if (rx < || rx >= bmp.Width || ry < || ry >= bmp.Height)
{
continue;
}
int rindex = ry * data.Stride + rx * ; result[index] = buf[rindex];
result[index + ] = buf[rindex + ];
result[index + ] = buf[rindex + ];
}
} Marshal.Copy(result, , data.Scan0, result.Length);
bmp.UnlockBits(data);
}
}
}
BitmapHelper
如果要处理图像，Paint.Net 是款不错的软件。