protected override unsafe void ProcessFilter( UnmanagedImage image, Rectangle rect )
{
int pixelSize = ( image.PixelFormat == PixelFormat.Format24bppRgb ) ? 3 : 4;
int startX = rect.Left;
int startY = rect.Top;
int stopX = startX + rect.Width;
int stopY = startY + rect.Height;
int offset = image.Stride - rect.Width * pixelSize;
// do the job
byte* ptr = (byte*) image.ImageData.ToPointer( );
byte t;
// allign pointer to the first pixel to process
ptr += ( startY * image.Stride + startX * pixelSize );
// for each line
for ( int y = startY; y < stopY; y++ )
{
// for each pixel
for ( int x = startX; x < stopX; x++, ptr += pixelSize )
{
t = (byte) ( 0.299 * ptr[RGB.R] + 0.587 * ptr[RGB.G] + 0.114 * ptr[RGB.B] );
// red
ptr[RGB.R] = (byte) ( ( t > 206 ) ? 255 : t + 49 );
// green
ptr[RGB.G] = (byte) ( ( t < 14 ) ? 0 : t - 14 );
// blue
ptr[RGB.B] = (byte) ( ( t < 56 ) ? 0 : t - 56 );
}
ptr += offset;
}
}
}