DETECTION DE CONTOURS

/*-----------------------------------------------------------------------------------------------*
//
//                                     Detecte Contours
//
//Fait par         : MaegisInstinct (maegisinstinct@free.fr)
//
//le               : 19/12/2004 à 22:21:43
//
//Description      : Detecte les contours d'une image
//
/*----------------------------------------------------------------------------------------------*/
#include <windows.h>
#include <math.h>
#include <stdlib.h>


struct PIXEL
{
	BYTE b;
	BYTE g;
	BYTE r;
};

struct Gradpix
{
	float r,g,b;
};


 [...]
/*-----------------------------------------------------*/
//Retourne la norme du gradient en un point de l'image
/*-----------------------------------------------------*/
Gradpix NormeGrad(PIXEL* image,int x,int y,int width,int height)
{
	Gradpix	 gradx	= {0.0f,0.0f,0.0f};
	Gradpix	 grady	= {0.0f,0.0f,0.0f};
	int		nbcompx = 0;
	int		nbcompy = 0;


	if (x != 0)
	{
		gradx.r += (float) image[x+y*width].r-image[x-1+y*width].r;
		gradx.g += (float) image[x+y*width].g-image[x-1+y*width].g;
		gradx.b += (float) image[x+y*width].b-image[x-1+y*width].b;
		nbcompx++;
	}
	if (x != width-1)
	{
		gradx.r += (float) image[(x+1)+y*width].r-image[x+y*width].r;
		gradx.g += (float) image[(x+1)+y*width].g-image[x+y*width].g;
		gradx.b += (float) image[(x+1)+y*width].b-image[x+y*width].b;
		nbcompx++;
	}
	gradx.r=gradx.r/(float)nbcompx;		//on fait la moyenne
	gradx.g=gradx.g/(float)nbcompx;
	gradx.b=gradx.b/(float)nbcompx;

	if (y != 0)
	{
		grady.r += (float) image[x+y*width].r-image[x+(y-1)*width].r;
		grady.g += (float) image[x+y*width].g-image[x+(y-1)*width].g;
		grady.b += (float) image[x+y*width].b-image[x+(y-1)*width].b;
		nbcompy++;
	}
	if (y != height-1)
	{
		grady.r += (float) image[x+(y+1)*width].r-image[x+y*width].r;
		grady.g += (float) image[x+(y+1)*width].g-image[x+y*width].g;
		grady.b += (float) image[x+(y+1)*width].b-image[x+y*width].b;
		nbcompy++;
	}
	grady.r=grady.r/(float)nbcompy;
	grady.g=grady.g/(float)nbcompy;
	grady.b=grady.b/(float)nbcompy;
	
	Gradpix result = {(float)sqrt(gradx.r*gradx.r+grady.r*grady.r),
			          (float)sqrt(gradx.g*gradx.g+grady.g*grady.g),
			          (float)sqrt(gradx.b*gradx.b+grady.b*grady.b)};
	return result;
}


/*------------------------------------------------------------------*/
//Genere une image contenant les contours de l'image passé en param
//durete : (entre 1 (soft) et 50 (tres dur))
/*------------------------------------------------------------------*/
PIXEL* DetecteContours(PIXEL* image,int width,int height,float durete)
{
	int i,j;
	Gradpix* grad = new Gradpix[width*height];

	for(j=0;j<height;j++)
	{
		for(i=0;i<width;i++)
		{
			grad[i+j*width] = NormeGrad(image,i,j,width,height);
		}
	}

	//On cherche le max et on normalise entre 0 et 255 et on genere l'image
	Gradpix maxi={0.0f,0.0f,0.0f};
	for (i=0;i<width*height;i++)
	{
		if (grad[i].r>maxi.r)
			maxi.r=grad[i].r;
		if (grad[i].g>maxi.g)
			maxi.g=grad[i].g;
		if (grad[i].b>maxi.b)
			maxi.b=grad[i].b;
	}
	//On genere ensuite l'image en normalisant
	PIXEL* data = new PIXEL[width*height];
	durete = max(durete,1);
	for (i=0;i<width*height;i++)
	{
		data[i].r = (BYTE) min(grad[i].r/maxi.r*255.0f*durete,255.0f);
		data[i].g = (BYTE) min(grad[i].g/maxi.g*255.0f*durete,255.0f);
		data[i].b = (BYTE) min(grad[i].b/maxi.b*255.0f*durete,255.0f);
	}
	
	return data;
}

/*--------------*/
//Fonction Main
/*--------------*/
int APIENTRY WinMain(HINSTANCE hInstance,
					 HINSTANCE hPrevInstance,
					 LPSTR lpCmdLine,
					 int nShowCmd)
{
	PIXEL *data;
	PIXEL *contours;
	DWORD width,height;
	char buffer[1024];

	if (*lpCmdLine == 0)
	{
		MessageBox(NULL,"Faites glisser un fichier bmp 24bpp sur l'exe","Info",MB_OK);
		return -1;
	}
	memcpy(buffer,lpCmdLine,strlen(lpCmdLine));
	buffer[strlen(lpCmdLine)-1]=0;	//On enleve le guillement droit

	if (GetBmp24(buffer+1,&data,width,height))
	{
		contours = DetecteContours(data,width,height,2);
		
		strcpy(buffer+strlen(lpCmdLine)-5,"-cont.bmp");
		SaveBmp24(buffer+1,contours,width,height);
		delete[] data;
		delete[] contours;
		return 0;
	}
	MessageBox(NULL,"Mauvais format de fichier","Erreur",MB_OK);
	return -1;
}