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

        protected override unsafe void ProcessFilter( UnmanagedImage image, Rectangle rect )
        {
            // processing start and stop X,Y positions
            startX = rect.Left;
            startY = rect.Top;
            stopX  = startX + rect.Width;
            stopY  = startY + rect.Height;
            stride = image.Stride;

            int offset = stride - rect.Width;

            // pixel value and error value
            int v, error;

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

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

            // for each line
            for ( y = startY; y < stopY; y++ )
            {
                // for each pixels
                for ( x = startX; x < stopX; x++, ptr++ )
                {
                    v = *ptr;

                    // fill the next destination pixel
                    if ( v >= threshold )
                    {
                        *ptr = 255;
                        error = v - 255;
                    }
                    else
                    {
                        *ptr = 0;
                        error = v;
                    }

                    // do error diffusion
                    Diffuse( error, ptr );
                }
                ptr += offset;
            }
        }
    }