Discussion :

[Teriblus]

Bonjour,

Je poste ce message pour faire part de ma récente expérience avec cvFindContours. Peut être que quelqu'un qui connait mieux que moi opencv pourra donner une explication au problème que j'ai rencontré !

J'utilise opencv pour faire un logiciel de reconnaissance de caractère que je souhaite baser sur la comparaison des contours stockés sous la forme de chain code. Pour les obtenir, j'utilise la fonction cvFindContours avec la méthode CV_CHAIN_CODE sur des images 32*32 contenant les lettres de l'alphabet avec un cadre blanc autour (lignes blanches ((0,0)(0,31) ; (0,0)(31,0) ; (31,31)(0,31) ; (0,31)(31,31)) (voir l'image C.png attachée).

L'appel

Code :

Sélectionner tout - Visualiser dans une fenêtre à part

cvFindContours(<c.bmp>, storage, &contour, sizeof(CvChain), CV_RETR_LIST, CV_CHAIN_CODE);

suivi de

Code :

Sélectionner tout - Visualiser dans une fenêtre à part

cvDrawContours(<c_border.bmp>, contour, CV_RGB(128,128,128)/*gris*/,CV_RGB(0,0,0)/*noir*/,1,1,8);

donne l'image C_border.png. Comme vous pouvez le voir, cela ne correspond pas vraiment aux contours extérieurs de la lettre C puisque les lignes extérieures restent blanches.

J'ai trouvé une méthode pour éviter le problème, mettre 3 lignes blanches en haut, en bas, à gauche et à droite au lieu d'une (comme pour B => B_border en pj). Le résultat est correct mais bon...

Si quelqu'un pouvait m'expliquer le pourquoi du comment, j'apprécierais :-) !
Merci !

PS : pour mieux voir les images, faire clic droit > enregistrer sous puis ouvrir et zoomer pour voir les pixels.

[snowpy]

Salut

Il me semble que le cvfind contour travail sur un histogramme de petit morceau de ton image, pour trouver les disparités le souci c'est que les bords de ton C sont collés au bords de ton image, est ce qu'en réalisant un C plus petit tu obtiens le même problème ?

[Teriblus]

Effectivement, lorsque je met la lettre plus au centre de l'image ça fonctionne, c'est d'ailleurs ce que j'ai fais pour la lettre B qui est en PJ du premier post.

J'obtiens le contours extérieur du B ainsi que les contours intérieurs. Par contre cvFindContours détecte également comme contour le plus extérieur la bordure grise que l'on peut voir autour du B dans l'image B_border. Et je ne comprend pas pourquoi ! (ce contour est également présent si la lettre est très petite par rapport à la taille de l'image)

Merci pour ta réponse,
Teriblus

[snowpy]

Tu dis que si tu color le contour en blanc, celui ci n'est plus détecté ?
Si oui es tu sur que ton contour d'origine est vraiment blanc, à savoir la valeur des pixels en héxa et non le rendu visuel ?

[Teriblus]

Voici le code hexa de ma lettre B (type bmp)

Code :

Sélectionner tout - Visualiser dans une fenêtre à part

42 4d 36 14 00 00 00 00 00 00 36 04 00 00 28 00 00 00 40 00 00 00 40 00 00 00 01 00 08 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 01 01 00 02 02 02 00 03 03 03 00 04 04 04 00 05 05 05 00 06 06 06 00 07 07 07 00 08 08 08 00 09 09 09 00 0a 0a 0a 00 0b 0b 0b 00 0c 0c 0c 00 0d 0d 0d 00 0e 0e 0e 00 0f 0f 0f 00 10 10 10 00 11 11 11 00 12 12 12 00 13 13 13 00 14 14 14 00 15 15 15 00 16 16 16 00 17 17 17 00 18 18 18 00 19 19 19 00 1a 1a 1a 00 1b 1b 1b 00 1c 1c 1c 00 1d 1d 1d 00 1e 1e 1e 00 1f 1f 1f 00 20 20 20 00 21 21 21 00 22 22 22 00 23 23 23 00 24 24 24 00 25 25 25 00 26 26 26 00 27 27 27 00 28 28 28 00 29 29 29 00 2a 2a 2a 00 2b 2b 2b 00 2c 2c 2c 00 2d 2d 2d 00 2e 2e 2e 00 2f 2f 2f 00 30 30 30 00 31 31 31 00 32 32 32 00 33 33 33 00 34 34 34 00 35 35 35 00 36 36 36 00 37 37 37 00 38 38 38 00 39 39 39 00 3a 3a 3a 00 3b 3b 3b 00 3c 3c 3c 00 3d 3d 3d 00 3e 3e 3e 00 3f 3f 3f 00 40 40 40 00 41 41 41 00 42 42 42 00 43 43 43 00 44 44 44 00 45 45 45 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99 99 99 00 9a 9a 9a 00 9b 9b 9b 00 9c 9c 9c 00 9d 9d 9d 00 9e 9e 9e 00 9f 9f 9f 00 a0 a0 a0 00 a1 a1 a1 00 a2 a2 a2 00 a3 a3 a3 00 a4 a4 a4 00 a5 a5 a5 00 a6 a6 a6 00 a7 a7 a7 00 a8 a8 a8 00 a9 a9 a9 00 aa aa aa 00 ab ab ab 00 ac ac ac 00 ad ad ad 00 ae ae ae 00 af af af 00 b0 b0 b0 00 b1 b1 b1 00 b2 b2 b2 00 b3 b3 b3 00 b4 b4 b4 00 b5 b5 b5 00 b6 b6 b6 00 b7 b7 b7 00 b8 b8 b8 00 b9 b9 b9 00 ba ba ba 00 bb bb bb 00 bc bc bc 00 bd bd bd 00 be be be 00 bf bf bf 00 c0 c0 c0 00 c1 c1 c1 00 c2 c2 c2 00 c3 c3 c3 00 c4 c4 c4 00 c5 c5 c5 00 c6 c6 c6 00 c7 c7 c7 00 c8 c8 c8 00 c9 c9 c9 00 ca ca ca 00 cb cb cb 00 cc cc cc 00 cd cd cd 00 ce ce ce 00 cf cf cf 00 d0 d0 d0 00 d1 d1 d1 00 d2 d2 d2 00 d3 d3 d3 00 d4 d4 d4 00 d5 d5 d5 00 d6 d6 d6 00 d7 d7 d7 00 d8 d8 d8 00 d9 d9 d9 00 da da da 00 db db db 00 dc dc dc 00 dd dd dd 00 de de de 00 df df df 00 e0 e0 e0 00 e1 e1 e1 00 e2 e2 e2 00 e3 e3 e3 00 e4 e4 e4 00 e5 e5 e5 00 e6 e6 e6 00 e7 e7 e7 00 e8 e8 e8 00 e9 e9 e9 00 ea ea ea 00 eb eb eb 00 ec ec ec 00 ed ed ed 00 ee ee ee 00 ef ef ef 00 f0 f0 f0 00 f1 f1 f1 00 f2 f2 f2 00 f3 f3 f3 00 f4 f4 f4 00 f5 f5 f5 00 f6 f6 f6 00 f7 f7 f7 00 f8 f8 f8 00 f9 f9 f9 00 fa fa fa 00 fb fb fb 00 fc fc fc 00 fd fd fd 00 fe fe fe 00 ff ff ff 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 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ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 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ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff

A part au départ (je suppose que c'est le header), on a bien une image en noir et blanc, profondeur 8bits et 1 seule couleur...

A moins que cvLoadImage modifie l'image... Je pense pas mais j’essaierais quand j'aurai un peu de temps.


Pour info le bout de code qui génère les images en pj du premier post :

Code :

Sélectionner tout - Visualiser dans une fenêtre à part

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void fonction (){
	char lettre = 'A';
	int i;
	IplImage* src;
	CvMemStorage* storage;
	CvSeq* contour = 0;
	char *filename = (char*) malloc(32*sizeof(char));
	for (i=1; i<=26; i++) {
		storage = cvCreateMemStorage(0);
		contour = 0;
 
 
		sprintf(filename, "/sdcard/OCR/ref/%c.bmp",lettre);
		if(!(src=cvLoadImage(filename, CV_LOAD_IMAGE_GRAYSCALE))) LOGE("ARG ! erreur load image");
 
		IplImage *negative = cvCreateImage( cvGetSize(src), IPL_DEPTH_8U, 1);
 
		cvFindContours(src, storage, &contour, sizeof(CvChain), CV_RETR_LIST, CV_CHAIN_CODE); // EXTERNAL => mieux mais marche pas... contour = null
 
 
		// draw the contours on a white image and save it
		IplImage* dst = cvCreateImage(cvGetSize(src), src->depth, src->nChannels);
		cvSet(dst , CV_RGB(255,255,255));
		//ext:gray //holes:black
		cvDrawContours(dst, contour, cvScalar(128),cvScalar(0),1,1,8);
		LOGE("Lettre %c", lettre);
		sprintf(filename, "/sdcard/OCR/%c.bmp",lettre);
		cvSaveImage(filename,dst);
 
		lettre++;
	}
	fclose(fcode);
	free(filename);
}

[Teriblus]

J'ai réglé le problème, en fait cvFindContour détecte les contours des éléments blancs sur un fond noir et je lui donnais des images noires sur fond blanc...

Ca fonctionne parfaitement à présent !

Merci pour vos réponses,
Teriblus