C++ How to create a large bitmap from a datalist stored in a deque? -

i building first ever program in c++ on , on again.

the program intended create picture, a gradient - parameters of height h, width l, in pixels, , 4 parameters of density da, db, dc, dd. gradient produced '1 bit' pixels: black or white - , simplest error-diffusion algorithm (so-called "naive" sometimes),

>> push error on next pixel of line.

after having performed optimization (deque instead of vector allows bigger images created ex.), stuck problem cannot solve now:

my pixel values being stored in deque, how transport them bitmap file?

i tried understand easybmp library couldn't find solution.

in code, can see line 33 tried (unsuccessfully) make .pbm header (portable bit map)

actually, i'd copy values of deque <int> dequea; (line 30) .bmp file or other raster file-format, instead of in .txt file happens line 72!

here's code, , nice picture of makes :

#include <iostream> #include <fstream> #include <vector> #include <deque> #include <iterator> #include <cstdlib> #include <string> #include <sstream> using namespace std;  // constant values  double   da=1;          //densities double   db=0.5; double   dc=0.5; double   dd=0;  double      l = 999;    //width & height => l = l+1  ///  999 = 1000 pixels double      h = 999;  //double      u = 1;    // unit  double      d = 0;      // gamma double      e = 0;      // error local vector <double> f;      // error dynamic  int main () {     // vector     deque <int> dequea;     f.push_back (0);      //dequea.push_back (2);     //fake pbm header (old)     //dequea.push_back (l+1);     //dequea.push_back (h+1);     //dequea.push_back (1);      float = 0;     float b = 0;                // local variables     double io = 0;              // variable i/o      while (a<l+1, b<h+1){          //values given & b         double dl = da-da*(b/h)+dc*(b/h);         double dr = db-db*(b/h)+dd*(b/h);         double d  = dl-dl*(a/l)+dr*(a/l); //gamma          if (e+0-d<=-0.5) {             dequea.push_back(1);             io = 1;         }          else {             dequea.push_back(0);             io = 0;         }          e = e+io-d;         f.push_back(e);          // next pixel & next line         a++;         if (a>l) {             = 0;             b = b++;             e = 0;             f.clear();         }     }     //export values .txt file     ofstream output_file("./test.txt");     ostream_iterator<int> output_iterator(output_file, "\n");     copy(dequea.begin(), dequea.end(), output_iterator);     dequea.clear(); } 

pbm files easy create , should suffice purpose. no need use external library.

a problem in original code storing both pbm metadata , actual image data in same dequea. don't that. mixing data makes program hard understand , maintain.

you can create valid pbm file adjusting code writing file:

ofstream output_file("./test.ppm");  // write file header output_file << "p1\n" << (l+1) << " " << (h+1) << "\n"; //write image data ostream_iterator<int> output_iterator(output_file, "\n"); copy(dequea.begin(), dequea.end(), output_iterator); 

the resulting ppm file works fine gimp.

writing bmp or tga file works same - first write header, followed actual data. main difference file formats binary files, file i/o looks bit different, , header , image data formats more complicated. still, both formats quite simple , easy write without using library.