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

        protected override unsafe void ProcessFilter( UnmanagedImage image )
        {
            // create integral image
            IntegralImage im = IntegralImage.FromBitmap( image );

            int width    = image.Width;
            int height   = image.Height;
            int widthM1  = width - 1;
            int heightM1 = height - 1;

            int offset = image.Stride - width;
            int radius = windowSize / 2;

            float avgBrightnessPart = 1.0f - pixelBrightnessDifferenceLimit;

            byte* ptr = (byte*) image.ImageData.ToPointer( );

            for ( int y = 0; y < height; y++ )
            {
                // rectangle's Y coordinates
                int y1 = y - radius;
                int y2 = y + radius;

                if ( y1 < 0 )
                    y1 = 0;
                if ( y2 > heightM1 )
                    y2 = heightM1;

                for ( int x = 0; x < width; x++, ptr++ )
                {
                    // rectangle's X coordinates
                    int x1 = x - radius;
                    int x2 = x + radius;

                    if ( x1 < 0 )
                        x1 = 0;
                    if ( x2 > widthM1 )
                        x2 = widthM1;

                    *ptr = (byte) ( ( *ptr < (int) ( im.GetRectangleMeanUnsafe( x1, y1, x2, y2 ) * avgBrightnessPart ) ) ? 0 : 255 );
                }

                ptr += offset;
            }
        }
    }