AForge.Imaging.Filters.Threshold.ProcessFilter C# (CSharp) Method

        protected override unsafe void ProcessFilter( UnmanagedImage image, Rectangle rect )
        {
            int startX  = rect.Left;
            int startY  = rect.Top;
            int stopX   = startX + rect.Width;
            int stopY   = startY + rect.Height;

            if ( image.PixelFormat == PixelFormat.Format8bppIndexed )
            {
                int offset = image.Stride - rect.Width;

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

                // allign pointer to the first pixel to process
                ptr += ( startY * image.Stride + startX );

                // for each line	
                for ( int y = startY; y < stopY; y++ )
                {
                    // for each pixel
                    for ( int x = startX; x < stopX; x++, ptr++ )
                    {
                        *ptr = (byte) ( ( *ptr >= threshold ) ? 255 : 0 );
                    }
                    ptr += offset;
                }
            }
            else
            {
                byte* basePtr = (byte*) image.ImageData.ToPointer( ) + startX * 2;
                int stride = image.Stride;

                // for each line	
                for ( int y = startY; y < stopY; y++ )
                {
                    ushort* ptr = (ushort*) ( basePtr + stride * y );

                    // for each pixel
                    for ( int x = startX; x < stopX; x++, ptr++ )
                    {
                        *ptr = (ushort) ( ( *ptr >= threshold ) ? 65535 : 0 );
                    }
                }
            }
        }
    }