保存32位的位图作为在C＃1比特.bmp文件 [英] Save a 32-bit Bitmap as 1-bit .bmp file in C#

问题描述

什么是转换和一个32位的位图保存到1位（黑/白）.bmp文件在C＃中最简单的方法？

What is the easiest way to convert and save a 32-bit Bitmap to a 1-bit (black/white) .bmp file in C#?

推荐答案

这code将完成这项工作：

This code will get the job done:

using System.Drawing.Imaging;
using System.Runtime.InteropServices;
...

public static Bitmap BitmapTo1Bpp(Bitmap img) {
  int w = img.Width;
  int h = img.Height;
  Bitmap bmp = new Bitmap(w, h, PixelFormat.Format1bppIndexed);
  BitmapData data = bmp.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, PixelFormat.Format1bppIndexed);
  byte[] scan = new byte[(w + 7) / 8];
  for (int y = 0; y < h; y++) {
    for (int x = 0; x < w; x++) {
      if (x % 8 == 0) scan[x / 8] = 0;
      Color c = img.GetPixel(x, y);
      if (c.GetBrightness() >= 0.5) scan[x / 8] |= (byte)(0x80 >> (x % 8));
    }
    Marshal.Copy(scan, 0, (IntPtr)((long)data.Scan0 + data.Stride * y), scan.Length);
  }
  bmp.UnlockBits(data);
  return bmp;
}

您可以加快步伐，如果有必要，通过使用不安全code来代替getPixel（）方法。

You can speed it up, if necessary, by using unsafe code to replace the GetPixel() method.

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