/* Structures permettant le stockage de l'image */
  typedef struct Pix_rgb
  {
  	unsigned char red;
  	unsigned char green;
  	unsigned char blue;
  } Pix_rgb;
  
  typedef struct Image
  {
  	int width;
  	int height;
  	Pix_rgb** Mat_data;
  } Image;
  
  
  
  /* Prototypes */ 
  void NouvelleImage(int width, int height, Image** I);
  void free_image(Image** I);
  void read_header(FILE * im_file, int *width, int *height);
  int sauvegarde_ppm(char* fichier, Image** I);
  int chargement_ppm(char *image_name, Image** I);
  void GetPartChar(unsigned char x, unsigned char *a, int i);
  void SetPartChar(unsigned char *x, unsigned char a, int i);
  void LSB_hide(Image **I, unsigned char *msg, int encode, int vigenere, unsigned char *cle);
  void Next_pixel(Image **I, int *current_pos, int *i, int *j, int vigenere, unsigned char *cle);