Hello,
i'm trying to calculate the contrast of pictures. At first a split the Array of the picture, so that I get little part arrays in these part arrays I calculate the the standard derivation and the mean score after that I divide these two values so that I get the contrast.
At first I tried to do this in LV (picture) but unfortunately the speed was not high enough, so I tried to write dll and hoped that this would do it more fast. Now the C Compiler doesn't deliver a error message but LV hangs every time I start it. So I don't know if my code is just very slow or if theres a problem with the code that I can't find.
Perhaps anybody here knows how I can improve or correct my C code if theres a problem with it or how I can speed up this calculations by other ways, perhaps theres even a better method in LV that I don't see.
Here is my Code:
[code]
/* Call Library source file */
#include "extcode.h"
#include
#include
#include
#ifdef __cplusplus
extern "C" {
#endif
/* LabVIEW created typedef */
typedef struct {
int32 dimSizes[2];
double elt[1];
} TD1;
typedef TD1 **TD1Hdl;
double* callocvector(int);
double* freevector(double*);
double** callocmatrix(int, int);
double** freematrix(double**,int);
_declspec(dllexport) long KontrastC(long *Brows, long *Bcols, long *Lcols, long *Lrows, TD1Hdl Bild, TD1Hdl Kontrast,long *test);
#ifdef __cplusplus
} // extern "C"
#endif
//Hauptprogramm Kontrastberechnung
long KontrastC(long *Brows, long *Bcols, long *Lcols, long *Lrows, TD1Hdl Bild, TD1Hdl Kontrast,long *test)
{
double** Mittelwert = callocmatrix(*Brows,*Bcols);
int i=0,j=0,m=0,n=0;
double ZWt=1.0/(*Lrows * *Lcols);
int ZWm=0, ZWn=0, ZWk=0;
/* dimSizes[0] is the number of rows */
int numrow = (*Bild)->dimSizes[0];
/* dimSizes[1] is the number of columns */
int numcol = (*Bild)->dimSizes[1];
numrow=floor(numrow / *Lrows);
numcol=floor(numcol / *Lcols);
//(*Kontrast)->elt[(3*numcol)+2]=(*Bild)->elt[(3*numcol)+2]*1000;
// Mittelwertsberechnung
for (m=0;m {
ZWm=m* *Lrows;
for(n=0;n {
ZWn=n* *Lcols;
for (i=0;i<*Lrows;i++)
{
for(j=0;j<*Lcols;j++)
{
Mittelwert[m][n]=Mittelwert[m][n]+ (*Bild)->elt[((i+ZWm)* numcol) + (j+ZWn)] ;
}
}
Mittelwert[m][n]=ZWt* Mittelwert[m][n];
(*Kontrast)->elt[(m*numcol)+n]=Mittelwert[m][n];
}
}
ZWm=0, ZWn=0;
//Kontrastberechnung
for (m=0;m {
ZWm=m* *Lrows;
for(n=0;n {
ZWn=n* *Lcols;
for (i=0;i<*Lrows;i++)
{
for(j=0;j<*Lcols;j++)
{
ZWk=((*Bild)->elt[((i+ZWm)*numcol) + (j+ZWn)]-Mittelwert[m][n]);
(*Kontrast)->elt[(m* numcol)+n]= (*Kontrast)->elt[(m*numcol)+n] + ( ZWk*ZWk );
}
}
(*Kontrast)->elt[(m*numcol)+n]=ZWt * (*Kontrast)->elt[(m*numcol)+n];
(*Kontrast)->elt[(m*numcol)+n]=(*Kontrast)->elt[(m*numcol)+n]/Mittelwert[m][n];
}
}
//Freigeben des reservierten Speichers
Mittelwert = freematrix(Mittelwert,*Lrows);
return 0;
}
//Unterprogramme zur dynamischen Speicherallokation
/*--------------------------------------------
"callocvector" allocates the memory for a
dynamic vector of length n and initializes it
--------------------------------------------*/
double* callocvector(int n)
{
int j;
double* vector = calloc(n,sizeof(double));
for (j=0; j {
vector[j] = 0;
}
return(vector);
}
/*--------------------------------------------
"freevector" dis-allocates the memory of
a dynamic vector of arbitrary length and
sets the pointer to NULL
--------------------------------------------*/
double* freevector(double* vector)
{
free(vector);
return(NULL);
}
/*--------------------------------------------
"callocmatrix" allocates the memory for a
dynamic matrix of size (m \times n)
and initializes it
--------------------------------------------*/
double** callocmatrix(int m, int n)
{
int i;
double** matrix = calloc(m,sizeof(double));
for (i=0; i {
matrix[i] = callocvector(n);
}
return(matrix);
}
/*--------------------------------------------
"freematrix" dis-allocates the memory of
a dynamic matrix of size (m \times n)
and sets the pointer to NULL
--------------------------------------------*/
double** freematrix(double** matrix,int m)
{
int i;
for (i=0; i {
free(matrix[i]);
}
free(matrix);
return(NULL);
}
[/code]
