Mon image BMP enregistrée est plus petite que mon image BMP chargée

**piponux** · 04/11/2016, 16h58

Bonjour, je suis un assidu des cours Youtube de Jacques Olivier Lapeyre. A ce titre, j'utilise ses modules pour apprendre le c. Je recommande vivement de regarder ses videos qui sont uniques sur le net pour qui veut apprendre le c. J'ai écrit un programme qui charge une image BMP et qui l'enregistre sur le disque dur. Seulement voilà, l'image du disque dur est plus petite que l'image chargée. Je vous livre mon code, constitué ici de deux fonctions : image_load_BMP24 et image_saveBMP24 + le main.

merci d'avance pour vos conseils éclairés.

Code :

Sélectionner tout - Visualiser dans une fenêtre à part

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void image_save_BMP24 (char* filename, imageBMP I)
{
 
fprintf(stderr, "\nFONCTION SAVE\n");
  jfile F = standard_jfile_open (filename, JFILE_MODE_WRITE);
   int i;
  unsigned char IdentifierB = I->IdentifierB;
  unsigned char IdentifierM = I->IdentifierM;
  unsigned int FileSize = I->FileSize;
  unsigned int Reserved =  I->Reserved;
  unsigned int DataOffset = I->DataOffset;
  unsigned int HeaderSize = I->HeaderSize;
 
  unsigned int width = I->w;
  unsigned int height = I->h;
 
  short int Planes = I->Planes;
  short int BitsPerPixel = I->BitsPerPixel;
  unsigned int Compression = I->Compression;
  unsigned int BitmapDataSize = I->BitmapDataSize;
  unsigned int HResolution = I->HResolution;
  unsigned int VResolution = I->VResolution;
  unsigned int Colours = I->Colours;
  unsigned int ImportantColours = I->ImportantColours;
 
  jfile_write_char (F, (unsigned char) I->IdentifierB);
    fprintf(stderr, "IdentifierB = %c\n", IdentifierB);
 
  jfile_write_char (F, (char) I->IdentifierM);
   fprintf(stderr, "IdentifierM = %c\n", IdentifierM);
 
 
  jfile_write_char (F, ((unsigned char) ((FileSize) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((FileSize >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((FileSize >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((FileSize >> 24) & 0xFF))); 
  fprintf(stderr, "FileSize = %d\n", FileSize);
 
  jfile_write_char (F, ((unsigned char) (Reserved & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Reserved >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Reserved >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Reserved >> 24) & 0xFF)));
  fprintf(stderr, "Reserved = %d\n", Reserved);
 
 
  jfile_write_char (F, ((unsigned char) (DataOffset & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((DataOffset >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((DataOffset >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((DataOffset >> 24) & 0xFF))); 
  fprintf(stderr, "DataOffset = %d\n", DataOffset);
 
 
  jfile_write_char (F, ((unsigned char) (HeaderSize & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((HeaderSize >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((HeaderSize >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((HeaderSize >> 24) & 0xFF)));   
  fprintf(stderr, "HeaderSize = %d\n", HeaderSize);
 
 
  jfile_write_char (F, ((unsigned char) (width & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((width >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((width >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((width >> 24) & 0xFF)));   
  fprintf(stderr, "width = %d\n", width);  
 
 
  jfile_write_char (F, ((unsigned char) (height & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((height >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((height >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((height >> 24) & 0xFF)));   
  fprintf(stderr, "height = %d\n", height); 
 
 
  jfile_write_char (F, ((unsigned char) (Planes & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Planes >> 8) & 0xFF))); 
  fprintf(stderr, "Planes = %d\n", Planes);
 
 
 
  jfile_write_char (F, ((unsigned char) (BitsPerPixel & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((BitsPerPixel >> 8) & 0xFF))); 
  fprintf(stderr, "BitesPerPixel = %d\n", BitsPerPixel); 
 
 
  jfile_write_char (F, ((unsigned char) (Compression & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Compression >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Compression >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Compression >> 24) & 0xFF)));   
  fprintf(stderr, "Compression = %d\n", Compression); 
 
 
  jfile_write_char (F, ((unsigned char) (BitmapDataSize & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((BitmapDataSize >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((BitmapDataSize >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((BitmapDataSize >> 24) & 0xFF)));  
  fprintf(stderr, "BitmapDataSize = %d\n", BitmapDataSize); 
 
 
 
  jfile_write_char (F, ((unsigned char) (HResolution & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((HResolution >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((HResolution >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((HResolution >> 24) & 0xFF)));   
  fprintf(stderr, "HResolution = %d\n", HResolution); 
 
 
  jfile_write_char (F, ((unsigned char) (VResolution & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((VResolution >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((VResolution >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((VResolution >> 24) & 0xFF)));   
  fprintf(stderr, "VResolution = %d\n", VResolution); 
 
 
  jfile_write_char (F, ((unsigned char) (Colours & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Colours >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Colours >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((Colours >> 24) & 0xFF)));   
  fprintf(stderr, "Nombre de couleurs dans l'image = %d\n", Colours); 
 
 
  jfile_write_char (F, ((unsigned char) (ImportantColours & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((ImportantColours >> 8) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((ImportantColours >> 16) & 0xFF))); 
  jfile_write_char (F, ((unsigned char) ((ImportantColours >> 24) & 0xFF)));   
  fprintf(stderr, "Nombre de couleurs importantes dans l'image = %d\n", ImportantColours); 
 
 
 
 
 
 
  for (i = 0; i < width * height; i++)
    {
      byte r, g, b;
      colour_get_rgb (I->pixel[i], &r, &g, &b);
      jfile_write_char (F, (unsigned char) b);
      jfile_write_char (F, (unsigned char) g);
      jfile_write_char (F, (unsigned char) r);
 
    }  
 
  jfile_close (&F);
}
 
 
 
 
image image_load_BMP24 (char* filename)
{
fprintf(stderr, "\nFONCTION LOAD\n");
  jfile F = standard_jfile_open (filename, JFILE_MODE_READ);
  imageBMP I;
  unsigned char c;
  int i;
   /*int w, h, i;*/
  unsigned char IdentifierB, IdentifierM;
  unsigned int FileSize; 
  unsigned int Reserved, DataOffset, HeaderSize, width, height;
  short int Planes, BitsPerPixel;
  unsigned int Compression, BitmapDataSize, HResolution, VResolution, Colours, ImportantColours;
 
  /*Identifier = 2 octects*/
  IdentifierB = (byte) jfile_read_char (F);
  fprintf(stderr, "IdentifierB = %c\n", IdentifierB);
 
  IdentifierM =  (byte) jfile_read_char (F);
  fprintf(stderr, "IdentifierM = %c\n", IdentifierM);
 
 
  /*FileSize = 4 octects*/ 
  FileSize = (byte) jfile_read_char (F);
  FileSize |=  (((byte) jfile_read_char (F)) << 8);
  FileSize |=  (((byte) jfile_read_char (F)) << 16);
  FileSize |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "FileSize = %d\n", FileSize);
 
  /*Reserved = 4 octects*/ 
  Reserved = (byte) jfile_read_char (F);
  Reserved |=  (((byte) jfile_read_char (F)) << 8);
  Reserved |=  (((byte) jfile_read_char (F)) << 16);
  Reserved |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "Reserved = %d\n", Reserved);
 
  /*DataOffset = 4 octets*/ 
  DataOffset = (byte) jfile_read_char (F);
  DataOffset |=  (((byte) jfile_read_char (F)) << 8);
  DataOffset |=  (((byte) jfile_read_char (F)) << 16);
  DataOffset |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "DataOffset = %d\n", DataOffset);
 
  /*HeaderSize = 4 octects*/
  HeaderSize = (byte) jfile_read_char (F);
  HeaderSize |=  (((byte) jfile_read_char (F)) << 8);
  HeaderSize |=  (((byte) jfile_read_char (F)) << 16);
  HeaderSize |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "HeaderSize = %d\n", HeaderSize);
 
  /*Width = 4 octets*/
  width = (byte) jfile_read_char (F);
  width |=  (((byte) jfile_read_char (F)) << 8);
  width |=  (((byte) jfile_read_char (F)) << 16);
  width |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "width = %d\n", width);  
 
  /*height = 4 octets*/
  height = (byte) jfile_read_char (F);
  height |=  (((byte) jfile_read_char (F)) << 8);
  height |=  (((byte) jfile_read_char (F)) << 16);
  height |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "height = %d\n", height); 
 
  /*Planes = 2 octets*/  
  Planes = (byte) jfile_read_char (F);
  Planes |=  (((byte) jfile_read_char (F)) << 8);
  fprintf(stderr, "Planes = %d\n", Planes);
 
  /*BitsPerPixel = 2 octets*/ 
  BitsPerPixel = (byte) jfile_read_char (F);
  BitsPerPixel |= ((byte) jfile_read_char (F) << 8);
  fprintf(stderr, "BitesPerPixel = %d\n", BitsPerPixel); 
 
  /*Compression (type de compression) = 4 octets*/
  Compression = (byte) jfile_read_char (F);
  Compression |=  (((byte) jfile_read_char (F)) << 8);
  Compression |=  (((byte) jfile_read_char (F)) << 16);
  Compression |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "Compression = %d\n", Compression); 
 
  /*BitmapDataSize (Taille en octets des données de l'image) = 4 octets*/
  BitmapDataSize = (byte) jfile_read_char (F);
  BitmapDataSize |=  (((byte) jfile_read_char (F)) << 8);
  BitmapDataSize |=  (((byte) jfile_read_char (F)) << 16);
  BitmapDataSize |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "BitmapDataSize = %d\n", BitmapDataSize); 
 
  /*HResolution (Résolution horizontale de l'image en pixels par mètre) = 4 octets*/ 
  HResolution = (byte) jfile_read_char (F);
  HResolution |=  (((byte) jfile_read_char (F)) << 8);
  HResolution |=  (((byte) jfile_read_char (F)) << 16);
  HResolution |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "HResolution = %d\n", HResolution); 
 
 
  /*VResolution (Résolution verticale de l'image en pixels par mètre) = 4 octets*/ 
  VResolution = (byte) jfile_read_char (F);
  VResolution |=  (((byte) jfile_read_char (F)) << 8);
  VResolution |=  (((byte) jfile_read_char (F)) << 16);
  VResolution |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "VResolution = %d\n", VResolution); 
 
 
  /*Colours (nombre de couleurs dans l'image) = 4 octets*/
  Colours = (byte) jfile_read_char (F);
  Colours |=  (((byte) jfile_read_char (F)) << 8);
  Colours |=  (((byte) jfile_read_char (F)) << 16);
  Colours |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "Nombre de couleurs dans l'image = %d\n", Colours); 
 
  /*ImportantColours (nombre de couleurs importantes dans l'image) = 4 octets*/
  ImportantColours = (byte) jfile_read_char (F);
  ImportantColours |=  (((byte) jfile_read_char (F)) << 8);
  ImportantColours |=  (((byte) jfile_read_char (F)) << 16);
  ImportantColours |=  (((byte) jfile_read_char (F)) << 24); 
  fprintf(stderr, "Nombre de couleurs importantes dans l'image = %d\n", ImportantColours); 
  fprintf(stderr, "1\n");
 
   I = imageBMP_malloc (width, height); 
   I->w = width;
   I->h = height;
   I->IdentifierB = IdentifierB;
   I->IdentifierM = IdentifierM;
   I->FileSize = FileSize;
   I->Reserved = Reserved;
   I->DataOffset = DataOffset;
   I->HeaderSize = HeaderSize;
   I->Planes = Planes;
   I->BitsPerPixel = BitsPerPixel;
   I->Compression = Compression;
   I->BitmapDataSize = BitmapDataSize;
   I->HResolution = HResolution;
   I->VResolution = VResolution;
   I->Colours = Colours;
   I->ImportantColours = ImportantColours;
 
 
 
    for (i = 0; i < I->w * I->h; i++)
      {
	byte r, g, b;
	b = (byte) jfile_read_char (F);
	g = (byte) jfile_read_char (F);
	r = (byte) jfile_read_char (F);
	I->pixel[i] = make_colour (r, g, b, 0xFF);
      }
        fprintf(stderr, "2\n");
 
  jfile_close (&F);
 
  return I;
}
 
 
void dessiner_disque_pleinBMP (imageBMP I)
{
   int cx, cy, radius;
   colour a;
   printf("\nEntrez le cx du disque : ");
   scanf("%d", &cx);
   printf("\nEntrez le cy du disque : ");
 
   scanf("%d", &cy);
   printf("\nEntrez le rayon du disque : ");
   scanf("%d", &radius);
   printf("\nQuelle couleur désirez-vous pour ce disque (en hexadecimal svp ) : ");
   scanf("%X", &a);
   /*image_draw_fullcircle (image I, int cx, int cy, int radius, colour c)*/
   image_draw_fullcircle (I, cx, cy, radius, a);
 
}
 
 
 
 
int main (int argc, char **argv)
{
 
imageBMP A = image_load_BMP24 ("vague.bmp");
image_save_BMP24 ("vagueBis.bmp", A);
imageBMP_destroy (&A);
 
if (argc < 0)
 
    fprintf (stderr, "%s",argv[-1]);
  return EXIT_SUCCESS;
}

**Médinoc** · 05/11/2016, 15h44

Cette partie est suspecte:

Code :

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for (i = 0; i < width * height; i++)
{
byte r, g, b;
colour_get_rgb (I->pixel[i], &r, &g, &b);
jfile_write_char (F, (unsigned char) b);
jfile_write_char (F, (unsigned char) g);
jfile_write_char (F, (unsigned char) r);
 
}

Parce qu'elle ne prend pas en compte le fait qu'une image bitmap doive être "DWORD-aligned": Chaque ligne doit être arrondie aux quatre octets supérieurs.

**piponux** · 05/11/2016, 19h19

Bonjour Medinoc.
C'est précisemment cette partie qui fait changer la taille de mon image lorsque je la bidouille.

**droggo** · 05/11/2016, 21h16

Bonjour,

Envoyé par piponux

Bonjour Medinoc.
C'est précisemment cette partie qui fait changer la taille de mon image lorsque je la bidouille.

Il ne faut pas "bidouiller", il faut respecter le format standard du fichier, facile à trouver.

**Médinoc** · 06/11/2016, 10h03

Le format standard n'est pas un problème, mais qu'en est-il du format de cette imageBMP? Est-elle supposée être DWORD-aligned elle aussi, ou pas?

**piponux** · 06/11/2016, 11h24

il semble effectivement que mon probleme vient du nombre de pixels en largeur.
voici un topic lu sur stack overflow :

http://stackoverflow.com/questions/1...rd-aligned-bit

je n'ai pas encore le niveau pour faire ce qu'il y est écrit. mais je pense avoir compris le principe.

Mon image BMP enregistrée est plus petite que mon image BMP chargée

C

Vue hybride

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