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

        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 )
                {
                    // rotate colors of each pixel
                    t = ptr[RGB.R];
                    ptr[RGB.R] = ptr[RGB.G];
                    ptr[RGB.G] = ptr[RGB.B];
                    ptr[RGB.B] = t;
                }
                ptr += offset;
            }
        }
    }