// sobel.cpp : Defines the entry point for the console application.
//
// Geovany A. Ramirez geoabi@gmail.com
// april 2009

#include "stdafx.h" // only for VC++, otherwise remove it
#include "cv.h"
#include "highgui.h"

int dx[3][3] = {{1,0,-1},{2,0,-2},{1,0,-1}};
int dy[3][3] = {{1,2,1},{0,0,0},{-1,-2,-1}};

//******** faster versions  *****************
// Sobel operator implementation using inderect access
void Sobel_ind_fast( IplImage* img, IplImage* dst)
{
	CvScalar s;
	for (int i=1; i < img->height-2; i++)
		for (int j=1; j < img->width-2; j++)
		{
			// apply kernel in X and Y directions
			int sum_x=0;
			int sum_y=0;
			for(int m=-1; m<=1; m++)
				for(int n=-1; n<=1; n++)
				{
					s=cvGet2D(img,i+m,j+n); // get the (i,j) pixel value
					sum_x+=(int)s.val[0]*dx[m+1][n+1];
					sum_y+=(int)s.val[0]*dy[m+1][n+1];
				}
			int sum=abs(sum_x)+abs(sum_y);
			s.val[0]=(sum>255)?255:sum;
			cvSet2D(dst,i,j,s); // set the (i,j) pixel value
		}
}

// Sobel operator implementation using direct access using a pointer
void Sobel_dir_fast( IplImage* img, IplImage* dst)
{

	int step = img->widthStep/sizeof(uchar);
	uchar* data = (uchar *)img->imageData;
	uchar* data_dst = (uchar *)dst->imageData;
	
	int s;
	for (int i=1; i < img->height-2; i++)
		for (int j=1; j < img->width-2; j++)
		{
			// apply kernel in X ans Y direction
			int sum_x=0;
			int sum_y=0;
			for(int m=-1; m<=1; m++)
				for(int n=-1; n<=1; n++)
				{
					s=data[(i+m)*step+j+n]; // get the (i,j) pixel value
					sum_x+=s*dx[m+1][n+1];
					sum_y+=s*dy[m+1][n+1];
				}
			int sum=abs(sum_x)+abs(sum_y);
			data_dst[i*step+j]=(sum>255)?255:sum; // set the (i,j) pixel value
		}
}
//******** end of faster versions  *****************

// Sobel operator implementation using inderect access
void Sobel_ind( IplImage* img, IplImage* dst)
{
	CvScalar s;
	for (int i=1; i < img->height-2; i++)
		for (int j=1; j < img->width-2; j++)
		{
			// apply kernel in X direction
			int sum_x=0;
			for(int m=-1; m<=1; m++)
				for(int n=-1; n<=1; n++)
				{
					s=cvGet2D(img,i+m,j+n); // get the (i,j) pixel value
					sum_x+=(int)s.val[0]*dx[m+1][n+1];
				}
			// apply kernel in Y direction
			int sum_y=0;
			for(int m=-1; m<=1; m++)
				for(int n=-1; n<=1; n++)
				{
					s=cvGet2D(img,i+m,j+n); // get the (i,j) pixel value
					sum_y+=(int)s.val[0]*dy[m+1][n+1];
				}
			int sum=abs(sum_x)+abs(sum_y);
			if (sum>255)
				sum=255;
			s.val[0]=sum;
			cvSet2D(dst,i,j,s); // set the (i,j) pixel value
		}
}
    
// Sobel operator implementation using direct access using a pointer
void Sobel_dir( IplImage* img, IplImage* dst)
{

	int step = img->widthStep/sizeof(uchar);
	uchar* data = (uchar *)img->imageData;
	uchar* data_dst = (uchar *)dst->imageData;
	
	int s;
	for (int i=1; i < img->height-2; i++)
		for (int j=1; j < img->width-2; j++)
		{
			// apply kernel in X direction
			int sum_x=0;
			for(int m=-1; m<=1; m++)
				for(int n=-1; n<=1; n++)
				{
					s=data[(i+m)*step+j+n]; // get the (i,j) pixel value
					sum_x+=s*dx[m+1][n+1];
				}
			// apply kernel in Y direction
			int sum_y=0;
			for(int m=-1; m<=1; m++)
				for(int n=-1; n<=1; n++)
				{
					s=data[(i+m)*step+j+n]; // get the (i,j) pixel value
					sum_y+=s*dy[m+1][n+1];
				}
			int sum=abs(sum_x)+abs(sum_y);
			if (sum>255)
				sum=255;
			data_dst[i*step+j]=sum; // set the (i,j) pixel value
		}
}

// display the Sobel output for the indicate sobel implementation
void show_sobel(IplImage* image, int v, int sh)
{
	IplImage *img = 0;
	IplImage *img_edg = 0;
	
	if( sh==1)
		cvShowImage( "Original image", image );

	img=cvCreateImage( cvSize(image->width,image->height), 8, 1 );
	
	if ( image->nChannels!=1)
		cvCvtColor( image, img, CV_BGR2GRAY );
	else
		cvCopy( image, img);

	img_edg = cvCreateImage( cvSize(image->width,image->height), 8, 1 );
	double t = (double)cvGetTickCount();
	
	const char* win_name;
	if (v==1) // inderect access
	{
		Sobel_ind_fast(img,img_edg);
		win_name="indirect access";
	}
	else if(v==2) // direct access using a pointer
	{
		Sobel_dir_fast(img,img_edg);
		win_name="direct access  ";
	}
	else // Default: opencv implementation
	{
		cvSobel( img, img_edg, 0, 1, 3 );
		win_name="OpenCV function";
	}
	
	t = (double)cvGetTickCount() - t;
	printf( "running time using %s = %gms\n",win_name, t/((double)cvGetTickFrequency()*1000.));

	cvShowImage( win_name, img_edg );
	
	cvReleaseImage( &img );
	cvReleaseImage( &img_edg );
}


int _tmain(int argc, _TCHAR* argv[])
{
	CvCapture* capture = 0;
	IplImage *image = 0;
	
	int v=0;

	cvNamedWindow( "Original image", 1 );
	cvNamedWindow( "indirect access", 1 );	
	cvNamedWindow( "direct access  ", 1 );	
	cvNamedWindow( "OpenCV function", 1 );	

	capture = cvCaptureFromCAM( 0 ); // Webcam
	if( capture )
		{
		IplImage *frame, *frame_copy = 0;
        for(;;)
        {
            
			if( !cvGrabFrame( capture ))
					break;
			frame = cvRetrieveFrame( capture );
			
			if( !frame )
                break;
            if( !frame_copy )
                frame_copy = cvCreateImage( cvSize(frame->width,frame->height),
                                            IPL_DEPTH_8U, frame->nChannels );
            if( frame->origin == IPL_ORIGIN_TL )
                cvCopy( frame, frame_copy, 0 );
            else
                cvFlip( frame, frame_copy, 0 );

	        show_sobel( frame_copy, v, 1);
			
			if( cvWaitKey( 10 ) > 0 )
				break;

        }

        cvReleaseImage( &frame_copy );
		cvReleaseCapture( &capture );
	}
	else
	{
		//const char* filename = (char*)"C:/Program Files/OpenCV/samples/c/box.png";
		const char* filename = (char*)"C:/Program Files/OpenCV/samples/c/fruits.jpg";
		image = cvLoadImage( filename, 1 );
		if (!image)
			printf( "can not read the image file\n");
		else
		{
			show_sobel( image ,1, 1);
			show_sobel( image ,2, 0);
			show_sobel( image ,3, 0);
			cvWaitKey(0);
		}
	}

	return 0;
}