托管C++ 图像快速读取

最新推荐文章于 2023-12-02 09:00:00 发布

qiumm

最新推荐文章于 2023-12-02 09:00:00 发布

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CC 4.0 BY-SA版权

文章标签： c++ system string

本文链接：https://blog.youkuaiyun.com/qiumm/article/details/5700169

本文介绍了如何使用C++通过Bitmap类和LockBits方法来快速读取和处理图像，避免了GetPixel和SetPixel的低效问题，实现了对大图片的高效操作。

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基于GetPixel 和 SetPixel 速度实在是太慢，处理大点的图片几乎崩溃的速度，幸好有解决方案~

   Bitmap^ bmp = gcnew Bitmap( "y.bmp" );

     Rectangle rect = Rectangle(0,0,bmp->Width,bmp->Height);
       System::Drawing::Imaging::BitmapData^ bmpData = bmp->LockBits( rect,   System::Drawing::Imaging::ImageLockMode::ReadWrite, bmp->PixelFormat );

// Get the address of the first line.
IntPtr ptr = bmpData->Scan0;

                // Declare an array to hold the bytes of the bitmap.
                // This code is specific to a bitmap with 24 bits per pixels.
     int bytes =   bmpData->Stride * bmp->Height ;
      array<Byte>^rgbValues = gcnew array<Byte>(bytes);

               // Copy the RGB values into the array.
              // System::Runtime::InteropServices::Marshal::Copy( ptr, rgbValues, 0, bytes );
      int PixelSize=3;
                // Set every third value to 255.
      for ( int y = 0; y < bmp->Height; y++ )
      {
       for ( int x = 0; x < bmp->Width; x ++ )
       {
        rgbValues[bmpData->Stride * y + 3*x] = 200;
        rgbValues[bmpData->Stride * y + 3*x + 1] = 200;
        rgbValues[bmpData->Stride * y + 3*x + 2] = 200;

       }

      }
             // Copy the RGB values back to the bitmap
     System::Runtime::InteropServices::Marshal::Copy( rgbValues, 0, ptr, bytes );
                 // Unlock the bits.
     bmp->UnlockBits( bmpData );
     picBox->Image = bmp;
     String^ filename = L"a.jpg";
     bmp->Save(filename);