如何转换像素格式？ 从Cb的32bppRGB到16bpp灰度

我需要为我的图像做一些阈值处理。 阈值滤波器function只接受8-16bpp灰度 。 我的位图图片具有32bppRGB像素格式。 请为此建议一些代码。 （我也想知道是否有可能没有逐像素操作）

ps我正在使用Aforge.NET进行阈值处理。

谢谢

-Sagar

Answer 1

最简单的方法：

public static Bitmap MakeGrayscale(Bitmap original) { //make an empty bitmap the same size as original Bitmap newBitmap = new Bitmap(original.Width, original.Height); for (int i = 0; i < original.Width; i++) { for (int j = 0; j < original.Height; j++) { //get the pixel from the original image Color originalColor = original.GetPixel(i, j); //create the grayscale version of the pixel int grayScale = (int)((originalColor.R * .3) + (originalColor.G * .59) + (originalColor.B * .11)); //create the color object Color newColor = Color.FromArgb(grayScale, grayScale, grayScale); //set the new image's pixel to the grayscale version newBitmap.SetPixel(i, j, newColor); } } return newBitmap; } 

更快的方式：

 public static Bitmap MakeGrayscale2(Bitmap original) { unsafe { //create an empty bitmap the same size as original Bitmap newBitmap = new Bitmap(original.Width, original.Height); //lock the original bitmap in memory BitmapData originalData = original.LockBits( new Rectangle(0, 0, original.Width, original.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb); //lock the new bitmap in memory BitmapData newData = newBitmap.LockBits( new Rectangle(0, 0, original.Width, original.Height), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb); //set the number of bytes per pixel int pixelSize = 3; for (int y = 0; y < original.Height; y++) { //get the data from the original image byte* oRow = (byte*)originalData.Scan0 + (y * originalData.Stride); //get the data from the new image byte* nRow = (byte*)newData.Scan0 + (y * newData.Stride); for (int x = 0; x < original.Width; x++) { //create the grayscale version byte grayScale = (byte)((oRow[x * pixelSize] * .11) + //B (oRow[x * pixelSize + 1] * .59) + //G (oRow[x * pixelSize + 2] * .3)); //R //set the new image's pixel to the grayscale version nRow[x * pixelSize] = grayScale; //B nRow[x * pixelSize + 1] = grayScale; //G nRow[x * pixelSize + 2] = grayScale; //R } } //unlock the bitmaps newBitmap.UnlockBits(newData); original.UnlockBits(originalData); return newBitmap; } } 

最快的方式：

 public static Bitmap MakeGrayscale3(Bitmap original) { //create a blank bitmap the same size as original Bitmap newBitmap = new Bitmap(original.Width, original.Height); //get a graphics object from the new image Graphics g = Graphics.FromImage(newBitmap); //create the grayscale ColorMatrix ColorMatrix colorMatrix = new ColorMatrix( new float[][] { new float[] {.3f, .3f, .3f, 0, 0}, new float[] {.59f, .59f, .59f, 0, 0}, new float[] {.11f, .11f, .11f, 0, 0}, new float[] {0, 0, 0, 1, 0}, new float[] {0, 0, 0, 0, 1} }); //create some image attributes ImageAttributes attributes = new ImageAttributes(); //set the color matrix attribute attributes.SetColorMatrix(colorMatrix); //draw the original image on the new image //using the grayscale color matrix g.DrawImage(original, new Rectangle(0, 0, original.Width, original.Height), 0, 0, original.Width, original.Height, GraphicsUnit.Pixel, attributes); //dispose the Graphics object g.Dispose(); return newBitmap; } 

Answer 2

使用AForge.NET框架灰度filter

滤镜接受24,32,48和64 bpp彩色图像，并产生8（如果源是24或32 bpp图像）或16（如果源是48或64 bpp图像）bpp灰度图像。

然后应用阈值filter。