OpenCV  3.3.1-dev
Open Source Computer Vision
Public Member Functions | Public Attributes | Protected Attributes | List of all members
cv::NAryMatIterator Class Reference

n-ary multi-dimensional array iterator. More...

#include "mat.hpp"

Public Member Functions

 NAryMatIterator ()
 the default constructor More...
 
 NAryMatIterator (const Mat **arrays, uchar **ptrs, int narrays=-1)
 the full constructor taking arbitrary number of n-dim matrices More...
 
 NAryMatIterator (const Mat **arrays, Mat *planes, int narrays=-1)
 the full constructor taking arbitrary number of n-dim matrices More...
 
void init (const Mat **arrays, Mat *planes, uchar **ptrs, int narrays=-1)
 the separate iterator initialization method More...
 
NAryMatIteratoroperator++ ()
 proceeds to the next plane of every iterated matrix More...
 
NAryMatIterator operator++ (int)
 proceeds to the next plane of every iterated matrix (postfix increment operator) More...
 

Public Attributes

const Mat ** arrays
 the iterated arrays More...
 
int narrays
 the number of arrays More...
 
size_t nplanes
 the number of hyper-planes that the iterator steps through More...
 
Matplanes
 the current planes More...
 
uchar ** ptrs
 data pointers More...
 
size_t size
 the size of each segment (in elements) More...
 

Protected Attributes

size_t idx
 
int iterdepth
 

Detailed Description

n-ary multi-dimensional array iterator.

Use the class to implement unary, binary, and, generally, n-ary element-wise operations on multi-dimensional arrays. Some of the arguments of an n-ary function may be continuous arrays, some may be not. It is possible to use conventional MatIterator 's for each array but incrementing all of the iterators after each small operations may be a big overhead. In this case consider using NAryMatIterator to iterate through several matrices simultaneously as long as they have the same geometry (dimensionality and all the dimension sizes are the same). On each iteration it.planes[0], it.planes[1],... will be the slices of the corresponding matrices.

The example below illustrates how you can compute a normalized and threshold 3D color histogram:

void computeNormalizedColorHist(const Mat& image, Mat& hist, int N, double minProb)
{
const int histSize[] = {N, N, N};
// make sure that the histogram has a proper size and type
hist.create(3, histSize, CV_32F);
// and clear it
hist = Scalar(0);
// the loop below assumes that the image
// is a 8-bit 3-channel. check it.
CV_Assert(image.type() == CV_8UC3);
MatConstIterator_<Vec3b> it = image.begin<Vec3b>(),
it_end = image.end<Vec3b>();
for( ; it != it_end; ++it )
{
const Vec3b& pix = *it;
hist.at<float>(pix[0]*N/256, pix[1]*N/256, pix[2]*N/256) += 1.f;
}
minProb *= image.rows*image.cols;
// initialize iterator (the style is different from STL).
// after initialization the iterator will contain
// the number of slices or planes the iterator will go through.
// it simultaneously increments iterators for several matrices
// supplied as a null terminated list of pointers
const Mat* arrays[] = {&hist, 0};
Mat planes[1];
NAryMatIterator itNAry(arrays, planes, 1);
double s = 0;
// iterate through the matrix. on each iteration
// itNAry.planes[i] (of type Mat) will be set to the current plane
// of the i-th n-dim matrix passed to the iterator constructor.
for(int p = 0; p < itNAry.nplanes; p++, ++itNAry)
{
threshold(itNAry.planes[0], itNAry.planes[0], minProb, 0, THRESH_TOZERO);
s += sum(itNAry.planes[0])[0];
}
s = 1./s;
itNAry = NAryMatIterator(arrays, planes, 1);
for(int p = 0; p < itNAry.nplanes; p++, ++itNAry)
itNAry.planes[0] *= s;
}

Constructor & Destructor Documentation

§ NAryMatIterator() [1/3]

cv::NAryMatIterator::NAryMatIterator ( )

the default constructor

§ NAryMatIterator() [2/3]

cv::NAryMatIterator::NAryMatIterator ( const Mat **  arrays,
uchar **  ptrs,
int  narrays = -1 
)

the full constructor taking arbitrary number of n-dim matrices

§ NAryMatIterator() [3/3]

cv::NAryMatIterator::NAryMatIterator ( const Mat **  arrays,
Mat planes,
int  narrays = -1 
)

the full constructor taking arbitrary number of n-dim matrices

Member Function Documentation

§ init()

void cv::NAryMatIterator::init ( const Mat **  arrays,
Mat planes,
uchar **  ptrs,
int  narrays = -1 
)

the separate iterator initialization method

§ operator++() [1/2]

NAryMatIterator& cv::NAryMatIterator::operator++ ( )

proceeds to the next plane of every iterated matrix

§ operator++() [2/2]

NAryMatIterator cv::NAryMatIterator::operator++ ( int  )

proceeds to the next plane of every iterated matrix (postfix increment operator)

Member Data Documentation

§ arrays

const Mat** cv::NAryMatIterator::arrays

the iterated arrays

§ idx

size_t cv::NAryMatIterator::idx
protected

§ iterdepth

int cv::NAryMatIterator::iterdepth
protected

§ narrays

int cv::NAryMatIterator::narrays

the number of arrays

§ nplanes

size_t cv::NAryMatIterator::nplanes

the number of hyper-planes that the iterator steps through

§ planes

Mat* cv::NAryMatIterator::planes

the current planes

§ ptrs

uchar** cv::NAryMatIterator::ptrs

data pointers

§ size

size_t cv::NAryMatIterator::size

the size of each segment (in elements)


The documentation for this class was generated from the following file: