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

        protected override unsafe void ProcessFilter( UnmanagedImage image, Rectangle rect )
        {
            int pixelSize = Image.GetPixelFormatSize( image.PixelFormat ) / 8;

            // processing start and stop X,Y positions
            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( );

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

            if ( image.PixelFormat == PixelFormat.Format8bppIndexed )
            {
                // grayscale image
                for ( int y = startY; y < stopY; y++ )
                {
                    for ( int x = startX; x < stopX; x++, ptr++ )
                    {
                        // gray
                        *ptr = grayMap[*ptr];
                    }
                    ptr += offset;
                }
            }
            else
            {
                // RGB image
                for ( int y = startY; y < stopY; y++ )
                {
                    for ( int x = startX; x < stopX; x++, ptr += pixelSize )
                    {
                        // red
                        ptr[RGB.R] = redMap[ptr[RGB.R]];
                        // green
                        ptr[RGB.G] = greenMap[ptr[RGB.G]];
                        // blue
                        ptr[RGB.B] = blueMap[ptr[RGB.B]];
                    }
                    ptr += offset;
                }
            }
        }
    }