Bitmap/Write a PPM file

Using the data storage type defined on this page for raster images, write the image to a PPM file (binary P6 prefered).
(Read the definition of PPM file on Wikipedia.)

C

<C>#include <stdio.h>

void output_ppm(FILE *fd, image img) {

   unsigned int n;
   fprintf(fd, "P6\n%d %d\n255\n", img->width, img->height);
   n = img->width * img->height;
   fwrite(img->buf, sizeof(pixel), n, fd);
   fflush(fd);

}</C>

OCaml

<ocaml>let output_ppm ~oc ~img:(_, r_channel, g_channel, b_channel) =

 let width = Bigarray.Array2.dim1 r_channel
 and height = Bigarray.Array2.dim2 r_channel in
 Printf.fprintf oc "P6\n%d %d\n255\n" width height;
 for y = 0 to pred height do
   for x = 0 to pred width do
     output_char oc (char_of_int r_channel.{x,y});
     output_char oc (char_of_int g_channel.{x,y});
     output_char oc (char_of_int b_channel.{x,y});
   done;
 done;
 output_char oc '\n';
 flush oc;