Opencv中的RNG类主要用来生成随机数，此类的定义如下：
class CV_EXPORTS RNG
{
public:
enum { UNIFORM=0, NORMAL=1 };
RNG();
RNG(uint64 _state);
//! updates the state and returns the next 32-bit unsigned integer random number
unsigned next();
operator uchar();
operator schar();
operator ushort();
operator short();
operator unsigned();
//! returns a random integer sampled uniformly from [0, N).
unsigned operator()(unsigned N);
unsigned operator ()();
operator int();
operator float();
operator double();
//! returns uniformly distributed integer random number from [a,b) range
int uniform(int a, int b);
//! returns uniformly distributed floating-point random number from [a,b) range
float uniform(float a, float b);
//! returns uniformly distributed double-precision floating-point random number from [a,b) range
double uniform(double a, double b);
void fill( InputOutputArray mat, int distType, InputArray a, InputArray b );
//! returns Gaussian random variate with mean zero.
double gaussian(double sigma);
uint64 state;
};
此类的定义中涉及到许多的运算符重载，在函数调用时应该予以注意。
double uniform(double a, double b)函数主要用来生成一个[a,b)范围内的一个随机数，主要通过如下实现
inline double RNG::uniform(double a, double b) { return ((double)*this)*(b - a) + a; }
这里的double用到了操作符的重载，*this主要作为一个右操作数，相等于函数的参数，重载操作的实现主要通过以下实现：
inline RNG::operator double()
{
unsigned t = next();
return (((uint64)t << 32) | next())*5.4210108624275221700372640043497e-20;
}