edge_aware.cpp

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#include "edge_aware.h"

#define AVG(a,b) (((int)(a) + (int)(b)) >> 1)
#define AVG3(a,b,c) (((int)(a) + (int)(b) + (int)(c)) / 3)
#define AVG4(a,b,c,d) (((int)(a) + (int)(b) + (int)(c) + (int)(d)) >> 2)
#define WAVG4(a,b,c,d,x,y)  ( ( ((int)(a) + (int)(b)) * (int)(x) + ((int)(c) + (int)(d)) * (int)(y) ) / ( 2 * ((int)(x) + (int(y))) ) )
using namespace std;

namespace image_proc {

void debayerEdgeAware(const cv::Mat& bayer, cv::Mat& color)
{
  unsigned width = bayer.cols;
  unsigned height = bayer.rows;
  unsigned rgb_line_step = color.step[0];
  unsigned rgb_line_skip = rgb_line_step - width * 3;
  int bayer_line_step = bayer.step[0];
  int bayer_line_step2 = bayer_line_step * 2;

  unsigned char* rgb_buffer = color.data;
  unsigned char* bayer_pixel = bayer.data;
  unsigned yIdx, xIdx;

  int dh, dv;

  // first two pixel values for first two lines
  // Bayer         0 1 2
  //         0     G r g
  // line_step     b g b
  // line_step2    g r g

  rgb_buffer[3] = rgb_buffer[0] = bayer_pixel[1]; // red pixel
  rgb_buffer[1] = bayer_pixel[0]; // green pixel
  rgb_buffer[rgb_line_step + 2] = rgb_buffer[2] = bayer_pixel[bayer_line_step]; // blue;

  // Bayer         0 1 2
  //         0     g R g
  // line_step     b g b
  // line_step2    g r g
  //rgb_pixel[3] = bayer_pixel[1];
  rgb_buffer[4] = AVG3 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1]);
  rgb_buffer[rgb_line_step + 5] = rgb_buffer[5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);

  // BGBG line
  // Bayer         0 1 2
  //         0     g r g
  // line_step     B g b
  // line_step2    g r g
  rgb_buffer[rgb_line_step + 3] = rgb_buffer[rgb_line_step ] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
  rgb_buffer[rgb_line_step + 1] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step + 1], bayer_pixel[bayer_line_step2]);
  //rgb_pixel[rgb_line_step + 2] = bayer_pixel[line_step];

  // pixel (1, 1)  0 1 2
  //         0     g r g
  // line_step     b G b
  // line_step2    g r g
  //rgb_pixel[rgb_line_step + 3] = AVG( bayer_pixel[1] , bayer_pixel[line_step2+1] );
  rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
  //rgb_pixel[rgb_line_step + 5] = AVG( bayer_pixel[line_step] , bayer_pixel[line_step+2] );

  rgb_buffer += 6;
  bayer_pixel += 2;
  // rest of the first two lines
  for (xIdx = 2; xIdx < width - 2; xIdx += 2, rgb_buffer += 6, bayer_pixel += 2)
  {
    // GRGR line
    // Bayer        -1 0 1 2
    //           0   r G r g
    //   line_step   g b g b
    // line_step2    r g r g
    rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
    rgb_buffer[1] = bayer_pixel[0];
    rgb_buffer[2] = bayer_pixel[bayer_line_step + 1];

    // Bayer        -1 0 1 2
    //          0    r g R g
    //  line_step    g b g b
    // line_step2    r g r g
    rgb_buffer[3] = bayer_pixel[1];
    rgb_buffer[4] = AVG3 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1]);
    rgb_buffer[rgb_line_step + 5] = rgb_buffer[5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);

    // BGBG line
    // Bayer         -1 0 1 2
    //         0      r g r g
    // line_step      g B g b
    // line_step2     r g r g
    rgb_buffer[rgb_line_step ] = AVG4 (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1], bayer_pixel[-1], bayer_pixel[bayer_line_step2 - 1]);
    rgb_buffer[rgb_line_step + 1] = AVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
    rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];

    // Bayer         -1 0 1 2
    //         0      r g r g
    // line_step      g b G b
    // line_step2     r g r g
    rgb_buffer[rgb_line_step + 3] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
    rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
    //rgb_pixel[rgb_line_step + 5] = AVG( bayer_pixel[line_step] , bayer_pixel[line_step+2] );
  }

  // last two pixel values for first two lines
  // GRGR line
  // Bayer        -1 0 1
  //           0   r G r
  //   line_step   g b g
  // line_step2    r g r
  rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
  rgb_buffer[1] = bayer_pixel[0];
  rgb_buffer[rgb_line_step + 5] = rgb_buffer[rgb_line_step + 2] = rgb_buffer[5] = rgb_buffer[2] = bayer_pixel[bayer_line_step];

  // Bayer        -1 0 1
  //          0    r g R
  //  line_step    g b g
  // line_step2    r g r
  rgb_buffer[3] = bayer_pixel[1];
  rgb_buffer[4] = AVG (bayer_pixel[0], bayer_pixel[bayer_line_step + 1]);
  //rgb_pixel[5] = bayer_pixel[line_step];

  // BGBG line
  // Bayer        -1 0 1
  //          0    r g r
  //  line_step    g B g
  // line_step2    r g r
  rgb_buffer[rgb_line_step ] = AVG4 (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1], bayer_pixel[-1], bayer_pixel[bayer_line_step2 - 1]);
  rgb_buffer[rgb_line_step + 1] = AVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
  //rgb_pixel[rgb_line_step + 2] = bayer_pixel[line_step];

  // Bayer         -1 0 1
  //         0      r g r
  // line_step      g b G
  // line_step2     r g r
  rgb_buffer[rgb_line_step + 3] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
  rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
  //rgb_pixel[rgb_line_step + 5] = bayer_pixel[line_step];

  bayer_pixel += bayer_line_step + 2;
  rgb_buffer += rgb_line_step + 6 + rgb_line_skip;
  // main processing
  for (yIdx = 2; yIdx < height - 2; yIdx += 2)
  {
    // first two pixel values
    // Bayer         0 1 2
    //        -1     b g b
    //         0     G r g
    // line_step     b g b
    // line_step2    g r g
    
    rgb_buffer[3] = rgb_buffer[0] = bayer_pixel[1]; // red pixel
    rgb_buffer[1] = bayer_pixel[0]; // green pixel
    rgb_buffer[2] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[-bayer_line_step]); // blue;
    
    // Bayer         0 1 2
    //        -1     b g b
    //         0     g R g
    // line_step     b g b
    // line_step2    g r g
    //rgb_pixel[3] = bayer_pixel[1];
    rgb_buffer[4] = AVG4 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1], bayer_pixel[1 - bayer_line_step]);
    rgb_buffer[5] = AVG4 (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2], bayer_pixel[-bayer_line_step], bayer_pixel[2 - bayer_line_step]);
    
    // BGBG line
    // Bayer         0 1 2
    //         0     g r g
    // line_step     B g b
    // line_step2    g r g
    rgb_buffer[rgb_line_step + 3] = rgb_buffer[rgb_line_step ] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
    rgb_buffer[rgb_line_step + 1] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step + 1], bayer_pixel[bayer_line_step2]);
    rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
    
    // pixel (1, 1)  0 1 2
    //         0     g r g
    // line_step     b G b
    // line_step2    g r g
    //rgb_pixel[rgb_line_step + 3] = AVG( bayer_pixel[1] , bayer_pixel[line_step2+1] );
    rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
    rgb_buffer[rgb_line_step + 5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
    
    rgb_buffer += 6;
    bayer_pixel += 2;
    // continue with rest of the line
    for (xIdx = 2; xIdx < width - 2; xIdx += 2, rgb_buffer += 6, bayer_pixel += 2)
    {
      // GRGR line
      // Bayer        -1 0 1 2
      //          -1   g b g b
      //           0   r G r g
      //   line_step   g b g b
      // line_step2    r g r g
      rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
      rgb_buffer[1] = bayer_pixel[0];
      rgb_buffer[2] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[-bayer_line_step]);
      
      // Bayer        -1 0 1 2
      //          -1   g b g b
      //          0    r g R g
      //  line_step    g b g b
      // line_step2    r g r g
      
      dh = abs (bayer_pixel[0] - bayer_pixel[2]);
      dv = abs (bayer_pixel[-bayer_line_step + 1] - bayer_pixel[bayer_line_step + 1]);
      
      if (dh > dv)
        rgb_buffer[4] = AVG (bayer_pixel[-bayer_line_step + 1], bayer_pixel[bayer_line_step + 1]);
      else if (dv > dh)
        rgb_buffer[4] = AVG (bayer_pixel[0], bayer_pixel[2]);
      else
        rgb_buffer[4] = AVG4 (bayer_pixel[-bayer_line_step + 1], bayer_pixel[bayer_line_step + 1], bayer_pixel[0], bayer_pixel[2]);
      
      rgb_buffer[3] = bayer_pixel[1];
      rgb_buffer[5] = AVG4 (bayer_pixel[-bayer_line_step], bayer_pixel[2 - bayer_line_step], bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
      
      // BGBG line
      // Bayer         -1 0 1 2
      //         -1     g b g b
      //          0     r g r g
      // line_step      g B g b
      // line_step2     r g r g
      rgb_buffer[rgb_line_step ] = AVG4 (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1], bayer_pixel[-1], bayer_pixel[bayer_line_step2 - 1]);
      rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
      
      dv = abs (bayer_pixel[0] - bayer_pixel[bayer_line_step2]);
      dh = abs (bayer_pixel[bayer_line_step - 1] - bayer_pixel[bayer_line_step + 1]);
      
      if (dv > dh)
        rgb_buffer[rgb_line_step + 1] = AVG (bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
      else if (dh > dv)
        rgb_buffer[rgb_line_step + 1] = AVG (bayer_pixel[0], bayer_pixel[bayer_line_step2]);
      else
        rgb_buffer[rgb_line_step + 1] = AVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
      
      // Bayer         -1 0 1 2
      //         -1     g b g b
      //          0     r g r g
      // line_step      g b G b
      // line_step2     r g r g
      rgb_buffer[rgb_line_step + 3] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
      rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
      rgb_buffer[rgb_line_step + 5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
    }
    
    // last two pixels of the line
    // last two pixel values for first two lines
    // GRGR line
    // Bayer        -1 0 1
    //           0   r G r
    //   line_step   g b g
    // line_step2    r g r
    rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
    rgb_buffer[1] = bayer_pixel[0];
    rgb_buffer[rgb_line_step + 5] = rgb_buffer[rgb_line_step + 2] = rgb_buffer[5] = rgb_buffer[2] = bayer_pixel[bayer_line_step];
    
    // Bayer        -1 0 1
    //          0    r g R
    //  line_step    g b g
    // line_step2    r g r
    rgb_buffer[3] = bayer_pixel[1];
    rgb_buffer[4] = AVG (bayer_pixel[0], bayer_pixel[bayer_line_step + 1]);
    //rgb_pixel[5] = bayer_pixel[line_step];
    
    // BGBG line
    // Bayer        -1 0 1
    //          0    r g r
    //  line_step    g B g
    // line_step2    r g r
    rgb_buffer[rgb_line_step ] = AVG4 (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1], bayer_pixel[-1], bayer_pixel[bayer_line_step2 - 1]);
    rgb_buffer[rgb_line_step + 1] = AVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
    //rgb_pixel[rgb_line_step + 2] = bayer_pixel[line_step];
    
    // Bayer         -1 0 1
    //         0      r g r
    // line_step      g b G
    // line_step2     r g r
    rgb_buffer[rgb_line_step + 3] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
    rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
    //rgb_pixel[rgb_line_step + 5] = bayer_pixel[line_step];
    
    bayer_pixel += bayer_line_step + 2;
    rgb_buffer += rgb_line_step + 6 + rgb_line_skip;
  }
  
  //last two lines
  // Bayer         0 1 2
  //        -1     b g b
  //         0     G r g
  // line_step     b g b
  
  rgb_buffer[rgb_line_step + 3] = rgb_buffer[rgb_line_step ] = rgb_buffer[3] = rgb_buffer[0] = bayer_pixel[1]; // red pixel
  rgb_buffer[1] = bayer_pixel[0]; // green pixel
  rgb_buffer[rgb_line_step + 2] = rgb_buffer[2] = bayer_pixel[bayer_line_step]; // blue;
  
  // Bayer         0 1 2
  //        -1     b g b
  //         0     g R g
  // line_step     b g b
  //rgb_pixel[3] = bayer_pixel[1];
  rgb_buffer[4] = AVG4 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1], bayer_pixel[1 - bayer_line_step]);
  rgb_buffer[5] = AVG4 (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2], bayer_pixel[-bayer_line_step], bayer_pixel[2 - bayer_line_step]);
  
  // BGBG line
  // Bayer         0 1 2
  //        -1     b g b
  //         0     g r g
  // line_step     B g b
  //rgb_pixel[rgb_line_step    ] = bayer_pixel[1];
  rgb_buffer[rgb_line_step + 1] = AVG (bayer_pixel[0], bayer_pixel[bayer_line_step + 1]);
  rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
  
  // Bayer         0 1 2
  //        -1     b g b
  //         0     g r g
  // line_step     b G b
  //rgb_pixel[rgb_line_step + 3] = AVG( bayer_pixel[1] , bayer_pixel[line_step2+1] );
  rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
  rgb_buffer[rgb_line_step + 5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
  
  rgb_buffer += 6;
  bayer_pixel += 2;
  // rest of the last two lines
  for (xIdx = 2; xIdx < width - 2; xIdx += 2, rgb_buffer += 6, bayer_pixel += 2)
  {
    // GRGR line
    // Bayer       -1 0 1 2
    //        -1    g b g b
    //         0    r G r g
    // line_step    g b g b
    rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
    rgb_buffer[1] = bayer_pixel[0];
    rgb_buffer[2] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[-bayer_line_step]);
    
    // Bayer       -1 0 1 2
    //        -1    g b g b
    //         0    r g R g
    // line_step    g b g b
    rgb_buffer[rgb_line_step + 3] = rgb_buffer[3] = bayer_pixel[1];
    rgb_buffer[4] = AVG4 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1], bayer_pixel[1 - bayer_line_step]);
    rgb_buffer[5] = AVG4 (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2], bayer_pixel[-bayer_line_step], bayer_pixel[-bayer_line_step + 2]);
    
    // BGBG line
    // Bayer       -1 0 1 2
    //        -1    g b g b
    //         0    r g r g
    // line_step    g B g b
    rgb_buffer[rgb_line_step ] = AVG (bayer_pixel[-1], bayer_pixel[1]);
    rgb_buffer[rgb_line_step + 1] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
    rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
    
    
    // Bayer       -1 0 1 2
    //        -1    g b g b
    //         0    r g r g
    // line_step    g b G b
    //rgb_pixel[rgb_line_step + 3] = bayer_pixel[1];
    rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
    rgb_buffer[rgb_line_step + 5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
  }
  
  // last two pixel values for first two lines
  // GRGR line
  // Bayer       -1 0 1
  //        -1    g b g
  //         0    r G r
  // line_step    g b g
  rgb_buffer[rgb_line_step ] = rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
  rgb_buffer[1] = bayer_pixel[0];
  rgb_buffer[5] = rgb_buffer[2] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[-bayer_line_step]);
  
  // Bayer       -1 0 1
  //        -1    g b g
  //         0    r g R
  // line_step    g b g
  rgb_buffer[rgb_line_step + 3] = rgb_buffer[3] = bayer_pixel[1];
  rgb_buffer[4] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step + 1], bayer_pixel[-bayer_line_step + 1]);
  //rgb_pixel[5] = AVG( bayer_pixel[line_step], bayer_pixel[-line_step] );
  
  // BGBG line
  // Bayer       -1 0 1
  //        -1    g b g
  //         0    r g r
  // line_step    g B g
  //rgb_pixel[rgb_line_step    ] = AVG2( bayer_pixel[-1], bayer_pixel[1] );
  rgb_buffer[rgb_line_step + 1] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
  rgb_buffer[rgb_line_step + 5] = rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
  
  // Bayer       -1 0 1
  //        -1    g b g
  //         0    r g r
  // line_step    g b G
  //rgb_pixel[rgb_line_step + 3] = bayer_pixel[1];
  rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
  //rgb_pixel[rgb_line_step + 5] = bayer_pixel[line_step];
}

void debayerEdgeAwareWeighted(const cv::Mat& bayer, cv::Mat& color)
{
  unsigned width = bayer.cols;
  unsigned height = bayer.rows;
  unsigned rgb_line_step = color.step[0];
  unsigned rgb_line_skip = rgb_line_step - width * 3;
  int bayer_line_step = bayer.step[0];
  int bayer_line_step2 = bayer_line_step * 2;

  unsigned char* rgb_buffer = color.data;
  unsigned char* bayer_pixel = bayer.data;
  unsigned yIdx, xIdx;

  int dh, dv;

  // first two pixel values for first two lines
  // Bayer         0 1 2
  //         0     G r g
  // line_step     b g b
  // line_step2    g r g

  rgb_buffer[3] = rgb_buffer[0] = bayer_pixel[1]; // red pixel
  rgb_buffer[1] = bayer_pixel[0]; // green pixel
  rgb_buffer[rgb_line_step + 2] = rgb_buffer[2] = bayer_pixel[bayer_line_step]; // blue;
  
  // Bayer         0 1 2
  //         0     g R g
  // line_step     b g b
  // line_step2    g r g
  //rgb_pixel[3] = bayer_pixel[1];
  rgb_buffer[4] = AVG3 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1]);
  rgb_buffer[rgb_line_step + 5] = rgb_buffer[5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
  
  // BGBG line
  // Bayer         0 1 2
  //         0     g r g
  // line_step     B g b
  // line_step2    g r g
  rgb_buffer[rgb_line_step + 3] = rgb_buffer[rgb_line_step ] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
  rgb_buffer[rgb_line_step + 1] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step + 1], bayer_pixel[bayer_line_step2]);
  //rgb_pixel[rgb_line_step + 2] = bayer_pixel[line_step];
  
  // pixel (1, 1)  0 1 2
  //         0     g r g
  // line_step     b G b
  // line_step2    g r g
  //rgb_pixel[rgb_line_step + 3] = AVG( bayer_pixel[1] , bayer_pixel[line_step2+1] );
  rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
  //rgb_pixel[rgb_line_step + 5] = AVG( bayer_pixel[line_step] , bayer_pixel[line_step+2] );
  
  rgb_buffer += 6;
  bayer_pixel += 2;
  // rest of the first two lines
  for (xIdx = 2; xIdx < width - 2; xIdx += 2, rgb_buffer += 6, bayer_pixel += 2)
  {
    // GRGR line
    // Bayer        -1 0 1 2
    //           0   r G r g
    //   line_step   g b g b
    // line_step2    r g r g
    rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
    rgb_buffer[1] = bayer_pixel[0];
    rgb_buffer[2] = bayer_pixel[bayer_line_step + 1];
    
    // Bayer        -1 0 1 2
    //          0    r g R g
    //  line_step    g b g b
    // line_step2    r g r g
    rgb_buffer[3] = bayer_pixel[1];
    rgb_buffer[4] = AVG3 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1]);
    rgb_buffer[rgb_line_step + 5] = rgb_buffer[5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
    
    // BGBG line
    // Bayer         -1 0 1 2
    //         0      r g r g
    // line_step      g B g b
    // line_step2     r g r g
    rgb_buffer[rgb_line_step ] = AVG4 (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1], bayer_pixel[-1], bayer_pixel[bayer_line_step2 - 1]);
    rgb_buffer[rgb_line_step + 1] = AVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
    rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
    
    // Bayer         -1 0 1 2
    //         0      r g r g
    // line_step      g b G b
    // line_step2     r g r g
    rgb_buffer[rgb_line_step + 3] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
    rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
    //rgb_pixel[rgb_line_step + 5] = AVG( bayer_pixel[line_step] , bayer_pixel[line_step+2] );
  }
  
  // last two pixel values for first two lines
  // GRGR line
  // Bayer        -1 0 1
  //           0   r G r
  //   line_step   g b g
  // line_step2    r g r
  rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
  rgb_buffer[1] = bayer_pixel[0];
  rgb_buffer[rgb_line_step + 5] = rgb_buffer[rgb_line_step + 2] = rgb_buffer[5] = rgb_buffer[2] = bayer_pixel[bayer_line_step];
  
  // Bayer        -1 0 1
  //          0    r g R
  //  line_step    g b g
  // line_step2    r g r
  rgb_buffer[3] = bayer_pixel[1];
  rgb_buffer[4] = AVG (bayer_pixel[0], bayer_pixel[bayer_line_step + 1]);
  //rgb_pixel[5] = bayer_pixel[line_step];
  
  // BGBG line
  // Bayer        -1 0 1
  //          0    r g r
  //  line_step    g B g
  // line_step2    r g r
  rgb_buffer[rgb_line_step ] = AVG4 (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1], bayer_pixel[-1], bayer_pixel[bayer_line_step2 - 1]);
  rgb_buffer[rgb_line_step + 1] = AVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
  //rgb_pixel[rgb_line_step + 2] = bayer_pixel[line_step];
  
  // Bayer         -1 0 1
  //         0      r g r
  // line_step      g b G
  // line_step2     r g r
  rgb_buffer[rgb_line_step + 3] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
  rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
  //rgb_pixel[rgb_line_step + 5] = bayer_pixel[line_step];
  
  bayer_pixel += bayer_line_step + 2;
  rgb_buffer += rgb_line_step + 6 + rgb_line_skip;
  // main processing
  for (yIdx = 2; yIdx < height - 2; yIdx += 2)
  {
    // first two pixel values
    // Bayer         0 1 2
    //        -1     b g b
    //         0     G r g
    // line_step     b g b
    // line_step2    g r g
    
    rgb_buffer[3] = rgb_buffer[0] = bayer_pixel[1]; // red pixel
    rgb_buffer[1] = bayer_pixel[0]; // green pixel
    rgb_buffer[2] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[-bayer_line_step]); // blue;
    
    // Bayer         0 1 2
    //        -1     b g b
    //         0     g R g
    // line_step     b g b
    // line_step2    g r g
    //rgb_pixel[3] = bayer_pixel[1];
    rgb_buffer[4] = AVG4 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1], bayer_pixel[1 - bayer_line_step]);
    rgb_buffer[5] = AVG4 (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2], bayer_pixel[-bayer_line_step], bayer_pixel[2 - bayer_line_step]);
    
    // BGBG line
    // Bayer         0 1 2
    //         0     g r g
    // line_step     B g b
    // line_step2    g r g
    rgb_buffer[rgb_line_step + 3] = rgb_buffer[rgb_line_step ] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
    rgb_buffer[rgb_line_step + 1] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step + 1], bayer_pixel[bayer_line_step2]);
    rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
    
    // pixel (1, 1)  0 1 2
    //         0     g r g
    // line_step     b G b
    // line_step2    g r g
    //rgb_pixel[rgb_line_step + 3] = AVG( bayer_pixel[1] , bayer_pixel[line_step2+1] );
    rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
    rgb_buffer[rgb_line_step + 5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
    
    rgb_buffer += 6;
    bayer_pixel += 2;
    // continue with rest of the line
    for (xIdx = 2; xIdx < width - 2; xIdx += 2, rgb_buffer += 6, bayer_pixel += 2)
    {
      // GRGR line
      // Bayer        -1 0 1 2
      //          -1   g b g b
      //           0   r G r g
      //   line_step   g b g b
      // line_step2    r g r g
      rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
      rgb_buffer[1] = bayer_pixel[0];
      rgb_buffer[2] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[-bayer_line_step]);
      
      // Bayer        -1 0 1 2
      //          -1   g b g b
      //          0    r g R g
      //  line_step    g b g b
      // line_step2    r g r g
      
      dh = abs (bayer_pixel[0] - bayer_pixel[2]);
      dv = abs (bayer_pixel[-bayer_line_step + 1] - bayer_pixel[bayer_line_step + 1]);
      
      if (dv == 0 && dh == 0)
        rgb_buffer[4] = AVG4 (bayer_pixel[1 - bayer_line_step], bayer_pixel[1 + bayer_line_step], bayer_pixel[0], bayer_pixel[2]);
      else
        rgb_buffer[4] = WAVG4 (bayer_pixel[1 - bayer_line_step], bayer_pixel[1 + bayer_line_step], bayer_pixel[0], bayer_pixel[2], dh, dv);
      rgb_buffer[3] = bayer_pixel[1];
      rgb_buffer[5] = AVG4 (bayer_pixel[-bayer_line_step], bayer_pixel[2 - bayer_line_step], bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
      
      // BGBG line
      // Bayer         -1 0 1 2
      //         -1     g b g b
      //          0     r g r g
      // line_step      g B g b
      // line_step2     r g r g
      rgb_buffer[rgb_line_step ] = AVG4 (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1], bayer_pixel[-1], bayer_pixel[bayer_line_step2 - 1]);
      rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
      
      dv = abs (bayer_pixel[0] - bayer_pixel[bayer_line_step2]);
      dh = abs (bayer_pixel[bayer_line_step - 1] - bayer_pixel[bayer_line_step + 1]);
      
      if (dv == 0 && dh == 0)
        rgb_buffer[rgb_line_step + 1] = AVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
      else
        rgb_buffer[rgb_line_step + 1] = WAVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1], dh, dv);
      
      // Bayer         -1 0 1 2
      //         -1     g b g b
      //          0     r g r g
      // line_step      g b G b
      // line_step2     r g r g
      rgb_buffer[rgb_line_step + 3] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
      rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
      rgb_buffer[rgb_line_step + 5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
    }
    
    // last two pixels of the line
    // last two pixel values for first two lines
    // GRGR line
    // Bayer        -1 0 1
    //           0   r G r
    //   line_step   g b g
    // line_step2    r g r
    rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
    rgb_buffer[1] = bayer_pixel[0];
    rgb_buffer[rgb_line_step + 5] = rgb_buffer[rgb_line_step + 2] = rgb_buffer[5] = rgb_buffer[2] = bayer_pixel[bayer_line_step];
    
    // Bayer        -1 0 1
    //          0    r g R
    //  line_step    g b g
    // line_step2    r g r
    rgb_buffer[3] = bayer_pixel[1];
    rgb_buffer[4] = AVG (bayer_pixel[0], bayer_pixel[bayer_line_step + 1]);
    //rgb_pixel[5] = bayer_pixel[line_step];
    
    // BGBG line
    // Bayer        -1 0 1
    //          0    r g r
    //  line_step    g B g
    // line_step2    r g r
    rgb_buffer[rgb_line_step ] = AVG4 (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1], bayer_pixel[-1], bayer_pixel[bayer_line_step2 - 1]);
    rgb_buffer[rgb_line_step + 1] = AVG4 (bayer_pixel[0], bayer_pixel[bayer_line_step2], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
    //rgb_pixel[rgb_line_step + 2] = bayer_pixel[line_step];
    
    // Bayer         -1 0 1
    //         0      r g r
    // line_step      g b G
    // line_step2     r g r
    rgb_buffer[rgb_line_step + 3] = AVG (bayer_pixel[1], bayer_pixel[bayer_line_step2 + 1]);
    rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
    //rgb_pixel[rgb_line_step + 5] = bayer_pixel[line_step];
    
    bayer_pixel += bayer_line_step + 2;
    rgb_buffer += rgb_line_step + 6 + rgb_line_skip;
  }
  
  //last two lines
  // Bayer         0 1 2
  //        -1     b g b
  //         0     G r g
  // line_step     b g b
  
  rgb_buffer[rgb_line_step + 3] = rgb_buffer[rgb_line_step ] = rgb_buffer[3] = rgb_buffer[0] = bayer_pixel[1]; // red pixel
  rgb_buffer[1] = bayer_pixel[0]; // green pixel
  rgb_buffer[rgb_line_step + 2] = rgb_buffer[2] = bayer_pixel[bayer_line_step]; // blue;
  
  // Bayer         0 1 2
  //        -1     b g b
  //         0     g R g
  // line_step     b g b
  //rgb_pixel[3] = bayer_pixel[1];
  rgb_buffer[4] = AVG4 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1], bayer_pixel[1 - bayer_line_step]);
  rgb_buffer[5] = AVG4 (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2], bayer_pixel[-bayer_line_step], bayer_pixel[2 - bayer_line_step]);
  
  // BGBG line
  // Bayer         0 1 2
  //        -1     b g b
  //         0     g r g
  // line_step     B g b
  //rgb_pixel[rgb_line_step    ] = bayer_pixel[1];
  rgb_buffer[rgb_line_step + 1] = AVG (bayer_pixel[0], bayer_pixel[bayer_line_step + 1]);
  rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];

  // Bayer         0 1 2
  //        -1     b g b
  //         0     g r g
  // line_step     b G b
  //rgb_pixel[rgb_line_step + 3] = AVG( bayer_pixel[1] , bayer_pixel[line_step2+1] );
  rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
  rgb_buffer[rgb_line_step + 5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
  
  rgb_buffer += 6;
  bayer_pixel += 2;
  // rest of the last two lines
  for (xIdx = 2; xIdx < width - 2; xIdx += 2, rgb_buffer += 6, bayer_pixel += 2)
  {
    // GRGR line
    // Bayer       -1 0 1 2
    //        -1    g b g b
    //         0    r G r g
    // line_step    g b g b
    rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
    rgb_buffer[1] = bayer_pixel[0];
    rgb_buffer[2] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[-bayer_line_step]);
    
    // Bayer       -1 0 1 2
    //        -1    g b g b
    //         0    r g R g
    // line_step    g b g b
    rgb_buffer[rgb_line_step + 3] = rgb_buffer[3] = bayer_pixel[1];
    rgb_buffer[4] = AVG4 (bayer_pixel[0], bayer_pixel[2], bayer_pixel[bayer_line_step + 1], bayer_pixel[1 - bayer_line_step]);
    rgb_buffer[5] = AVG4 (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2], bayer_pixel[-bayer_line_step], bayer_pixel[-bayer_line_step + 2]);

    // BGBG line
    // Bayer       -1 0 1 2
    //        -1    g b g b
    //         0    r g r g
    // line_step    g B g b
    rgb_buffer[rgb_line_step ] = AVG (bayer_pixel[-1], bayer_pixel[1]);
    rgb_buffer[rgb_line_step + 1] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
    rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
    
    
    // Bayer       -1 0 1 2
    //        -1    g b g b
    //         0    r g r g
    // line_step    g b G b
    //rgb_pixel[rgb_line_step + 3] = bayer_pixel[1];
    rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
    rgb_buffer[rgb_line_step + 5] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[bayer_line_step + 2]);
  }
  
  // last two pixel values for first two lines
  // GRGR line
  // Bayer       -1 0 1
  //        -1    g b g
  //         0    r G r
  // line_step    g b g
  rgb_buffer[rgb_line_step ] = rgb_buffer[0] = AVG (bayer_pixel[1], bayer_pixel[-1]);
  rgb_buffer[1] = bayer_pixel[0];
  rgb_buffer[5] = rgb_buffer[2] = AVG (bayer_pixel[bayer_line_step], bayer_pixel[-bayer_line_step]);
  
  // Bayer       -1 0 1
  //        -1    g b g
  //         0    r g R
  // line_step    g b g
  rgb_buffer[rgb_line_step + 3] = rgb_buffer[3] = bayer_pixel[1];
  rgb_buffer[4] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step + 1], bayer_pixel[-bayer_line_step + 1]);
  //rgb_pixel[5] = AVG( bayer_pixel[line_step], bayer_pixel[-line_step] );
  
  // BGBG line
  // Bayer       -1 0 1
  //        -1    g b g
  //         0    r g r
  // line_step    g B g
  //rgb_pixel[rgb_line_step    ] = AVG2( bayer_pixel[-1], bayer_pixel[1] );
  rgb_buffer[rgb_line_step + 1] = AVG3 (bayer_pixel[0], bayer_pixel[bayer_line_step - 1], bayer_pixel[bayer_line_step + 1]);
  rgb_buffer[rgb_line_step + 5] = rgb_buffer[rgb_line_step + 2] = bayer_pixel[bayer_line_step];
  
  // Bayer       -1 0 1
  //        -1    g b g
  //         0    r g r
  // line_step    g b G
  //rgb_pixel[rgb_line_step + 3] = bayer_pixel[1];
  rgb_buffer[rgb_line_step + 4] = bayer_pixel[bayer_line_step + 1];
  //rgb_pixel[rgb_line_step + 5] = bayer_pixel[line_step];

}

} // namespace image_proc