(C++ OpenCV) Histogram equalization

// Disclaimer: This code employs bad programming style
// Please improve. I (Bilderbikkel) cannot do so, as I do not have
// OpenCV installed on my computer anymore.
include <cv.h>


void histogramEqualize(const IplImage * const pSource, IplImage * pTarget)
{
	assert(pSource!=NULL);
	assert(pTarget!=NULL);
	assert(pSource->nChannels ==1);
	assert(pTarget->nChannels ==1); 
	assert(pSource->width == pTarget->width);
	assert(pSource->height == pTarget->height);
	CvHistogram *hist;
	uchar lut[256];
	double lut1[256];
	CvMat* lut_mat;
	int hist_size = 256;
	float range_0[]={0,256};
	float* ranges[] = { range_0 };
		
	int high=0;
	int low =0;
	float hist_value = 0.0;
	
	hist = cvCreateHist(1, &hist_size, CV_HIST_ARRAY, ranges, 1);
	lut_mat = cvCreateMatHeader( 1, 256, CV_8UC1 );
	cvSetData( lut_mat, lut, 0 );
	//cvCalcHist( &pSource, hist, 0, NULL );
	cvCalcHist( const_cast<IplImage**>(&pSource), hist, 0, NULL );
	
	//CUMULATIVE ARRAY
	lut1[0] = 0;
	for(int index = 0; index != hist_size; ++index)
	     {
	         hist_value = cvQueryHistValue_1D(hist,index);
			lut1[index+1]= lut1[index] + hist_value;
	     }
	
	
	//CALCULATE THE NEW LUT
	float scale_factor;
	scale_factor = 255.0f / (float) (pSource->width * pSource->height);
	for (int index=0; index!=256; ++index)
	{
		lut[index]= (unsigned char)((float)lut1[index]*scale_factor);
	}
	//PERFORM IT ON THE CHANNEL
	cvLUT( pSource, pTarget, lut_mat );
	cvReleaseMat( &lut_mat);
	cvReleaseHist(&hist);
}

Code links

• assert
• const

'Histogram equalization' links

• C++ VCL
• general