using Spire.Pdf.Conversion;

namespace ToGrayPDF
{
    class Program
    {
        static void Main(string[] args)
        {
            //創(chuàng)建一個PdfGrayConverter實(shí)例并加載文檔
            PdfGrayConverter converter = new PdfGrayConverter("sample.pdf");

            //將彩色PDF轉(zhuǎn)換為灰度
            converter.ToGrayPdf("Grayscale.pdf");
            converter.Dispose();
        }
    }
}

Imports Spire.Pdf.Conversion

Namespace ToGrayPDF
    Class Program
        Private Shared Sub Main(args As String())
            '創(chuàng)建一個PdfGrayConverter實(shí)例并加載文檔
            Dim converter As New PdfGrayConverter("sample.pdf")

            '將彩色PDF轉(zhuǎn)換為灰度
            converter.ToGrayPdf("Grayscale.pdf")
            converter.Dispose()
        End Sub
    End Class
End Namespace

public static Bitmap ChangeGray(Bitmap b) 
 { 
  BitmapData bmData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadWrite, 
   PixelFormat.Format24bppRgb); 
  int stride = bmData.Stride;   // 掃描的寬度 
   
   
  unsafe
  { 
   byte* p = (byte*)bmData.Scan0.ToPointer(); // 獲取圖像首地址 
   int nOffset = stride - b.Width * 3;  // 實(shí)際寬度與系統(tǒng)寬度的距離 
   byte red, green, blue; 
   for (int y = 0; y < b.Height; ++y) 
   { 
    for (int x = 0; x < b.Width; ++x) 
    { 
     blue = p[0]; 
     green = p[1]; 
     red = p[2]; 
   
     p[0] = p[1] = p[2] = (byte)(.299 * red + .587 * green + .114 * blue); // 轉(zhuǎn)換公式 
     p += 3;  // 跳過3個字節(jié)處理下個像素點(diǎn) 
    } 
    p += nOffset; // 加上間隔 
   } 
  } 
  b.UnlockBits(bmData); // 解鎖 
  return b; 
 }