将24bpp位图转换为1bpp

我试图转换一个小位图图像。 我想任何不是100％白色的像素都可以转换成黑色。 我试过了

Bitmap output = sourceImage.Clone(new Rectangle(0, 0, sourceImage.Width, sourceImage.Height), PixelFormat.Format1bppIndexed); 

在1bpp输出中仍然有一些较亮的像素保持白色。 实现此转换的最快方法是什么？ 我可以修改Clone（）调用的强度阈值吗？

Answer 1

试试这个，从非常快的1bpp转换 ：

从此处复制将图像转换为1bpp时的阈值？ 。

  private static unsafe void Convert(Bitmap src, Bitmap conv) { // Lock source and destination in memory for unsafe access var bmbo = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadOnly, src.PixelFormat); var bmdn = conv.LockBits(new Rectangle(0, 0, conv.Width, conv.Height), ImageLockMode.ReadWrite, conv.PixelFormat); var srcScan0 = bmbo.Scan0; var convScan0 = bmdn.Scan0; var srcStride = bmbo.Stride; var convStride = bmdn.Stride; byte* sourcePixels = (byte*)(void*)srcScan0; byte* destPixels = (byte*)(void*)convScan0; var srcLineIdx = 0; var convLineIdx = 0; var hmax = src.Height-1; var wmax = src.Width-1; for (int y = 0; y < hmax; y++) { // find indexes for source/destination lines // use addition, not multiplication? srcLineIdx += srcStride; convLineIdx += convStride; var srcIdx = srcLineIdx; for (int x = 0; x < wmax; x++) { // index for source pixel (32bbp, rgba format) srcIdx += 4; //var r = pixel[2]; //var g = pixel[1]; //var b = pixel[0]; // could just check directly? //if (Color.FromArgb(r,g,b).GetBrightness() > 0.01f) if (!(sourcePixels[srcIdx] == 0 && sourcePixels[srcIdx + 1] == 0 && sourcePixels[srcIdx + 2] == 0)) { // destination byte for pixel (1bpp, ie 8pixels per byte) var idx = convLineIdx + (x >> 3); // mask out pixel bit in destination byte destPixels[idx] |= (byte)(0x80 >> (x & 0x7)); } } } src.UnlockBits(bmbo); conv.UnlockBits(bmdn); }