hyperbolic_cuber.cpp

/* Histogram 2/3 degrees */ 
float hyperbolic_cube_root(unsigned char* inbuf, unsigned char* outbuf, int height, int width){

int g_min=255;
int g_max=0;
double* histogram = new double[256]; /* histogram array 0..255*/
double* cdf = new double[256]; /*Pf(f) cumulative distrib function */
double* out = new double[height*width];
int start = GetTickCount();
   for(int i=0;i<256;i++) {
     histogram[i] = 0;
     out[i]=0;
   }
/* Counting histogram values */
double d=1.0/(double)(height*width);
for(int i=0;i<height;i++){
   for(int j=0;j<width;j++)
   {
     if(inbuf[i*width+j]<g_min) g_min = inbuf[i*width+j];
     if(inbuf[i*width+j]>g_max) g_max = inbuf[i*width+j];
     histogram[inbuf[i*width+j]]+=d;
   }
 }
/*Counting Pf(f) function [cumsum]*/
cdf[0]=histogram[0];
 for(int i=1;i<256;i++)
   cdf[i]=(cdf[i-1]+histogram[i]);

double max=-999,min=999;
for(int i=0;i<height;i++){
   for(int j=0;j<width;j++){

/*finding elements of out by function */

out[i*width+j]=pow( ( pow(g_max,0.33) - pow(g_min,0.33) ) * cdf[inbuf[i*width+j]] + pow(g_min,0.33), 3 );
   if(out[i*width+j]>max)max=out[i*width+j];
   if(out[i*width+j]<min)min=out[i*width+j];
   }
}
//double to unsigned char
for(int i=0;i<height;i++)
   for(int j=0;j<width;j++)
      outbuf[i*width+j]=(unsigned char)(out[i*width+j]-min)/(max-min)*255;

return (float)(GetTickCount()-start);
}