c++ - optimization issue with splitting an image into channels -


enter image description here

here code, "algorithm" trying take bayer image, or rgb image, , separate channel g, luma (or grayscale) different channels of color,

an example bayer pattern

enter image description here

void utilities::separatechannels(int* channelr, int* channelg, int* channelb, double*& gr, double*& r, double*& b, double*& gb,int _width, int _height, int _colororder) {     //swith case color order     int counter_r = 0;     int counter_gr = 0;     int counter_gb = 0;     int counter_b = 0;      switch (_colororder)     {          //grbg     case 0:          (int j = 0; j < _width; j++)         {                        (int = 0; < _height; i++)             {                 if (i % 2 == 0 && j % 2 == 0)                 {                                         gr[counter_gr] = channelg[i*_width+ j];                     counter_gr++;                 }                 else if (i % 2 == 0 && j % 2 == 1)                 {                     r[counter_r] = channelg[i*_width+ j];                     counter_r++;                 }                 else if (i % 2 == 1 && j % 2 == 0)                 {                     b[counter_b] =channelg[i*_width+ j];                     counter_b++;                 }                 else if (i % 2 == 1 && j % 2 == 1)                 {                     gb[counter_gb] = channelg[i*_width+ j];                     counter_gb++;                 }             }         }

i ran profiler on 70 images, attached results. can suggest way optimize code?

swap loops, first iterate on height. can calculate * _width before second loop , calculate 1 time instead of _width times.


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