AForge.Imaging.Filters.ReplaceChannel.ProcessFilter C# (CSharp) Метод

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

            if ( ( channel == RGB.A ) && ( pixelSize != 4 ) && ( pixelSize != 8 ) )
            {
                throw new InvalidImagePropertiesException( "Can not replace alpha channel of none ARGB image." );
            }

            int width   = image.Width;
            int height  = image.Height;
            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;

            BitmapData chData = null;
            // pointer to channel's data
            byte* ch;
            // channel's image stride
            int chStride = 0;
            PixelFormat chFormat = PixelFormat.Format16bppGrayScale;

            // check channel's image type
            if ( channelImage != null )
            {
                // check channel's image dimension
                if ( ( width != channelImage.Width ) || ( height != channelImage.Height ) )
                    throw new InvalidImagePropertiesException( "Channel image size does not match source image size." );

                // lock channel image
                chData = channelImage.LockBits(
                    new Rectangle( 0, 0, width, height ),
                    ImageLockMode.ReadOnly, channelImage.PixelFormat );

                ch = (byte*) chData.Scan0.ToPointer( );
                chStride = chData.Stride;
                chFormat = chData.PixelFormat;
            }
            else
            {
                // check channel's image dimension
                if ( ( width != unmanagedChannelImage.Width ) || ( height != unmanagedChannelImage.Height ) )
                    throw new InvalidImagePropertiesException( "Channel image size does not match source image size." );

                ch = (byte*) unmanagedChannelImage.ImageData;
                chStride = unmanagedChannelImage.Stride;
                chFormat = unmanagedChannelImage.PixelFormat;
            }

            if ( pixelSize <= 4 )
            {
                // check channel image's format
                if ( chFormat != PixelFormat.Format8bppIndexed )
                    throw new InvalidImagePropertiesException( "Channel image's format does not correspond to format of the source image." );

                int offsetCh = chData.Stride - rect.Width;

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

                // allign pointers to the first pixel to process
                dst += ( startY * image.Stride + startX * pixelSize );
                ch  += ( startY * chStride + startX );

                // for each line
                for ( int y = startY; y < stopY; y++ )
                {
                    // for each pixel
                    for ( int x = startX; x < stopX; x++, dst += pixelSize, ch++ )
                    {
                        dst[channel] = *ch;
                    }
                    dst += offset;
                    ch += offsetCh;
                }
            }
            else
            {
                // check channel image's format
                if ( chFormat != PixelFormat.Format16bppGrayScale )
                    throw new InvalidImagePropertiesException( "Channel image's format does not correspond to format of the source image." );

                int stride = image.Stride;

                // do the job
                byte* baseDst = (byte*) image.ImageData.ToPointer( );
                // allign pointers for X coordinate
                baseDst += startX * pixelSize;
                ch += startX * 2;

                pixelSize /= 2;

                // for each line
                for ( int y = startY; y < stopY; y++ )
                {
                    ushort* dst = (ushort*) ( baseDst + y * stride );
                    ushort* chPtr = (ushort*) ( ch + y * chStride );

                    // for each pixel
                    for ( int x = startX; x < stopX; x++, dst += pixelSize, chPtr++ )
                    {
                        dst[channel] = *chPtr;
                    }
                }
            }

            if ( chData != null )
            {
                // unlock
                channelImage.UnlockBits( chData );
            }
        }
    }