BitMiracle.LibJpeg.Classic.Internal.jpeg_downsampler.h2v1_downsample C# (CSharp) Method

        private void h2v1_downsample(int componentIndex, byte[][] input_data, int startInputRow, byte[][] output_data, int startOutRow)
        {
            /* Expand input data enough to let all the output samples be generated
             * by the standard loop.  Special-casing padded output would be more
             * efficient.
             */
            jpeg_component_info compptr = m_cinfo.Component_info[componentIndex];
            int output_cols = compptr.Width_in_blocks * compptr.DCT_h_scaled_size;
            expand_right_edge(input_data, startInputRow, m_cinfo.m_max_v_samp_factor, m_cinfo.m_image_width, output_cols * 2);

            for (int outrow = 0; outrow < m_cinfo.m_max_v_samp_factor; outrow++)
            {
                /* bias = 0,1,0,1,... for successive samples */
                int bias = 0;
                int inputColumn = 0;
                for (int outcol = 0; outcol < output_cols; outcol++)
                {
                    output_data[startOutRow + outrow][outcol] = (byte)(
                        ((int)input_data[startInputRow + outrow][inputColumn] +
                        (int)input_data[startInputRow + outrow][inputColumn + 1] + bias) >> 1);

                    bias ^= 1;      /* 0=>1, 1=>0 */
                    inputColumn += 2;
                }
            }
        }