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

        protected override unsafe void ProcessFilter( UnmanagedImage image, Rectangle rect )
        {
            if ( mask != null )
            {
                if ( ( image.Width  != mask.GetLength( 1 ) ) ||
                     ( image.Height != mask.GetLength( 0 ) ) )
                {
                    throw new ArgumentException( "Invalid size of mask array. Its size must be the same as the size of the image to mask." );
                }

                fixed ( byte* maskPtr = mask )
                {
                    ProcessImage( image, rect, maskPtr, mask.GetLength( 1 ) );
                }
            }
            else if ( unmanagedMaskImage != null )
            {
                if ( ( image.Width  != unmanagedMaskImage.Width ) ||
                     ( image.Height != unmanagedMaskImage.Height ) )
                {
                    throw new ArgumentException( "Invalid size of unmanaged mask image. Its size must be the same as the size of the image to mask." );
                }

                ProcessImage( image, rect, (byte*) unmanagedMaskImage.ImageData.ToPointer( ),
                              unmanagedMaskImage.Stride );
            }
            else if ( maskImage != null )
            {
                if ( ( image.Width  != maskImage.Width ) ||
                     ( image.Height != maskImage.Height ) )
                {
                    throw new ArgumentException( "Invalid size of mask image. Its size must be the same as the size of the image to mask." );
                }

                BitmapData maskData = maskImage.LockBits( new Rectangle( 0, 0, image.Width, image.Height ),
                    ImageLockMode.ReadOnly, PixelFormat.Format8bppIndexed );

                try
                {
                    ProcessImage( image, rect, (byte*) maskData.Scan0.ToPointer( ),
                                  maskData.Stride );
                }
                finally
                {
                    maskImage.UnlockBits( maskData );
                }
            }
            else
            {
                throw new NullReferenceException( "None of the possible mask properties were set. Need to provide mask before applying the filter." );
            }
        }