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

        private void int_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;
            int h_expand = this.h_expand[compptr.Component_index];
            expand_right_edge(input_data, startInputRow, m_cinfo.m_max_v_samp_factor, m_cinfo.m_image_width, output_cols * h_expand);

            int v_expand = this.v_expand[compptr.Component_index];
            int numpix = h_expand * v_expand;
            int numpix2 = numpix / 2;
            int inrow = 0;
            int outrow = 0;
            while (inrow < m_cinfo.m_max_v_samp_factor)
            {
                for (int outcol = 0, outcol_h = 0; outcol < output_cols; outcol++, outcol_h += h_expand)
                {
                    int outvalue = 0;
                    for (int v = 0; v < v_expand; v++)
                    {
                        for (int h = 0; h < h_expand; h++)
                            outvalue += input_data[startInputRow + inrow + v][outcol_h + h];
                    }

                    output_data[startOutRow + outrow][outcol] = (byte)((outvalue + numpix2) / numpix);
                }

                inrow += v_expand;
                outrow++;
            }
        }