Accord.Imaging.Filters.Intersect.ProcessFilter C# (CSharp) Method

        protected override unsafe void ProcessFilter( UnmanagedImage image, UnmanagedImage overlay )
        {
            PixelFormat pixelFormat = image.PixelFormat;
            // get image dimension
            int width  = image.Width;
            int height = image.Height;

            if (
                ( pixelFormat == PixelFormat.Format8bppIndexed ) ||
                ( pixelFormat == PixelFormat.Format24bppRgb ) ||
                ( pixelFormat == PixelFormat.Format32bppRgb ) ||
                ( pixelFormat == PixelFormat.Format32bppArgb ) )
            {
                // initialize other variables
                int pixelSize = ( pixelFormat == PixelFormat.Format8bppIndexed ) ? 1 :
                    ( pixelFormat == PixelFormat.Format24bppRgb ) ? 3 : 4;
                int lineSize  = width * pixelSize;
                int srcOffset = image.Stride - lineSize;
                int ovrOffset = overlay.Stride - lineSize;

                // do the job
                byte * ptr = (byte*) image.ImageData.ToPointer( );
                byte * ovr = (byte*) overlay.ImageData.ToPointer( );

                // for each line
                for ( int y = 0; y < height; y++ )
                {
                    // for each pixel
                    for ( int x = 0; x < lineSize; x++, ptr++, ovr++ )
                    {
                        if ( *ovr < *ptr )
                            *ptr = *ovr;
                    }
                    ptr += srcOffset;
                    ovr += ovrOffset;
                }
            }
            else
            {
                // initialize other variables
                int pixelSize = ( pixelFormat == PixelFormat.Format16bppGrayScale ) ? 1 :
                    ( pixelFormat == PixelFormat.Format48bppRgb ) ? 3 : 4;
                int lineSize  = width * pixelSize;
                int srcStride = image.Stride;
                int ovrStride = overlay.Stride;

                // do the job
                byte* basePtr = (byte*) image.ImageData.ToPointer( );
                byte* baseOvr = (byte*) overlay.ImageData.ToPointer( );

                // for each line
                for ( int y = 0; y < height; y++ )
                {
                    ushort * ptr = (ushort*) ( basePtr + y * srcStride );
                    ushort * ovr = (ushort*) ( baseOvr + y * ovrStride );

                    // for each pixel
                    for ( int x = 0; x < lineSize; x++, ptr++, ovr++ )
                    {
                        if ( *ovr < *ptr )
                            *ptr = *ovr;
                    }
                }
            }
        }
    }