/*
 * Isaias Gonzalez <siderevs@gmail.com>
 * 1D Histogram with OpenCV
 */

#include <cv.h>

#include <highgui.h>
#include <stdio.h>

IplImage* image= 0;
IplImage* imgHistogram = 0;
IplImage* gray= 0;

CvHistogram* hist;

int main( int argc, char** argv ){

	if( argc != 2 || !( image = cvLoadImage( argv[1] ) ) ) {
		return -1;
	}

	// size of the histogram -1D histogram
	int bins = 256;
	int hsize[] = { bins };

	// max and min value of the histogram
	float max_value = 0, min_value = 0;

	// value and normalized value
	float value;
	int normalized;

	//ranges - grayscale 0 to 256
	float xranges[] = { 0, 256 };
	float* ranges[] = { xranges };

	// create an 8 bit single channel image to hold a
	// grayscale version of the original picture
	gray = cvCreateImage( cvGetSize( image ), 8, 1 );
	cvCvtColor( image, gray, CV_BGR2GRAY );

	// Create 3 windows to show the results
	cvNamedWindow( "original", 1 );
	cvNamedWindow( "gray", 1 );
	cvNamedWindow( "histogram", 1 );

	// planes to obtain the histogram, in this case just one
	IplImage* planes[] = { gray };

	// get the histogram and some info about it
	hist = cvCreateHist( 1, hsize, CV_HIST_ARRAY, ranges, 1 );
	cvCalcHist( planes, hist, 0, NULL );
	cvGetMinMaxHistValue( hist, &min_value, &max_value );
	printf( "min: %f, max: %f\n", min_value, max_value );

	// create an 8 bits single channel image to hold the histogram
	// paint it white
	imgHistogram = cvCreateImage( cvSize( bins, 50 ), 8, 1 );
	cvRectangle( imgHistogram, cvPoint( 0, 0 ), cvPoint( 256, 50 ), CV_RGB( 255, 255, 255 ), -1 );

	// draw the histogram :P
	for( int i = 0; i < bins; i++ ) {
		value = cvQueryHistValue_1D( hist, i );
		normalized = cvRound( value * 50 / max_value );
	//	printf( "%d\n", normalized );
		cvLine( imgHistogram, cvPoint( i, 50 ), cvPoint( i, 50 - normalized ), CV_RGB( 0, 0, 0 ) );
	}

	// show the image results
	cvShowImage( "original", image );
	cvShowImage( "gray", gray );
	cvShowImage( "histogram", imgHistogram );

	cvWaitKey();
	
	cvReleaseImage( &imgHistogram );
	cvReleaseImage( &image );
	cvReleaseImage( &gray );
	cvReleaseHist( &hist );

	return 0;
}