# cv::Mat Class Reference

`#include <core.hpp>`

Inheritance diagram for cv::Mat:

List of all members.

## Classes

struct | MSize
struct | MStep

## Public Types

enum | { MAGIC_VAL = 0x42FF0000, AUTO_STEP = 0, CONTINUOUS_FLAG = CV_MAT_CONT_FLAG, SUBMATRIX_FLAG = CV_SUBMAT_FLAG }

## Public Member Functions

void | addref ()
| increases the reference counter; use with care to avoid memleaks
Mat & | adjustROI (int dtop, int dbottom, int dleft, int dright)
| moves/resizes the current matrix ROI inside the parent matrix.
void | assignTo (Mat &m, int type=-1) const
template<typename _Tp >
_Tp & | at (int i0=0)
| the same as above, with the pointer dereferencing
template<typename _Tp >
const _Tp & | at (int i0=0) const
template<typename _Tp >
_Tp & | at (int i0, int i1)
template<typename _Tp >
const _Tp & | at (int i0, int i1) const
template<typename _Tp >
_Tp & | at (int i0, int i1, int i2)
template<typename _Tp >
const _Tp & | at (int i0, int i1, int i2) const
template<typename _Tp >
_Tp & | at (const int *idx)
template<typename _Tp >
const _Tp & | at (const int *idx) const
template<typename _Tp , int n>
_Tp & | at (const Vec< int, n > &idx)
template<typename _Tp , int n>
const _Tp & | at (const Vec< int, n > &idx) const
template<typename _Tp >
_Tp & | at (Point pt)
| special versions for 2D arrays (especially convenient for referencing image pixels)
template<typename _Tp >
const _Tp & | at (Point pt) const
template<typename _Tp >
MatIterator_< _Tp > | begin ()
| template methods for iteration over matrix elements.
template<typename _Tp >
MatConstIterator_< _Tp > | begin () const
int | channels () const
| returns element type, similar to CV_MAT_CN(cvmat->type)
int | checkVector (int elemChannels, int depth=-1, bool requireContinuous=true) const
| returns N if the matrix is 1-channel (N x ptdim) or ptdim-channel (1 x N) or (N x 1); negative number otherwise
Mat | clone () const
| returns deep copy of the matrix, i.e. the data is copied
Mat | col (int x) const
| returns a new matrix header for the specified column
Mat | colRange (const Range &r) const
Mat | colRange (int startcol, int endcol) const
| ... for the specified column span
void | convertTo (Mat &m, int rtype, double alpha=1, double beta=0) const
| converts matrix to another datatype with optional scalng. See cvConvertScale.
void | copySize (const Mat &m)
| internal use function; properly re-allocates _size, _step arrays
void | copyTo (Mat &m) const
| copies the matrix content to "m".
void | copyTo (Mat &m, const Mat &mask) const
| copies those matrix elements to "m" that are marked with non-zero mask elements.
template<typename _Tp >
void | copyTo (vector< _Tp > &v) const
void | create (Size _size, int _type)
void | create (int _rows, int _cols, int _type)
| allocates new matrix data unless the matrix already has specified size and type.
void | create (int _ndims, const int *_sizes, int _type)
Mat | cross (const Mat &m) const
| computes cross-product of 2 3D vectors
void | deallocate ()
| deallocates the matrix data
int | depth () const
| returns element type, similar to CV_MAT_DEPTH(cvmat->type)
Mat | diag (int d=0) const
| ... for the specified diagonal
double | dot (const Mat &m) const
| computes dot-product
size_t | elemSize () const
| returns element size in bytes,
size_t | elemSize1 () const
| returns the size of element channel in bytes.
bool | empty () const
| returns true if matrix data is NULL
template<typename _Tp >
MatIterator_< _Tp > | end ()
template<typename _Tp >
MatConstIterator_< _Tp > | end () const
MatExpr | inv (int method=DECOMP_LU) const
| matrix inversion by means of matrix expressions
bool | isContinuous () const
| returns true iff the matrix data is continuous
bool | isSubmatrix () const
| returns true if the matrix is a submatrix of another matrix
void | locateROI (Size &wholeSize, Point &ofs) const
| locates matrix header within a parent matrix. See below
| Mat (int _rows, int _cols, int _type, const Scalar &_s)
| constucts 2D matrix and fills it with the specified value _s.
| Mat (const CvMatND *m, bool copyData=false)
| converts old-style CvMatND to the new matrix; the data is not copied by default
| Mat (const Mat &m)
| copy constructor
| Mat (const IplImage *img, bool copyData=false)
| converts old-style IplImage to the new matrix; the data is not copied by default
| Mat (int _rows, int _cols, int _type)
| constructs 2D matrix of the specified size and type
template<typename _Tp >
| Mat (const vector< _Tp > &vec, bool copyData=false)
| builds matrix from std::vector with or without copying the data
| Mat (int _rows, int _cols, int _type, void *_data, size_t _step=AUTO_STEP)
| constructor for matrix headers pointing to user-allocated data
template<typename _Tp , int n>
| Mat (const Vec< _Tp, n > &vec, bool copyData=true)
| builds matrix from cv::Vec; the data is copied by default
template<typename _Tp , int m, int n>
| Mat (const Matx< _Tp, m, n > &mtx, bool copyData=true)
| builds matrix from cv::Matx; the data is copied by default
| Mat (Size _size, int _type, void *_data, size_t _step=AUTO_STEP)
template<typename _Tp >
| Mat (const Point_< _Tp > &pt, bool copyData=true)
| builds matrix from a 2D point
| Mat (Size _size, int _type, const Scalar &_s)
| Mat (int _ndims, const int *_sizes, int _type, void *_data, const size_t *_steps=0)
template<typename _Tp >
| Mat (const Point3_< _Tp > &pt, bool copyData=true)
| builds matrix from a 3D point
template<typename _Tp >
| Mat (const MatCommaInitializer_< _Tp > &commaInitializer)
| builds matrix from comma initializer
| Mat (int _ndims, const int *_sizes, int _type)
| constructs n-dimensional matrix
| Mat (const Mat &m, const Range &rowRange, const Range &colRange=Range::all())
| creates a matrix header for a part of the bigger matrix
| Mat (const Mat &m, const Rect &roi)
| Mat ()
| default constructor
| Mat (const Mat &m, const Range *ranges)
| Mat (int _ndims, const int *_sizes, int _type, const Scalar &_s)
| Mat (Size _size, int _type)
| Mat (const CvMat *m, bool copyData=false)
| converts old-style CvMat to the new matrix; the data is not copied by default
MatExpr | mul (const Mat &m, double scale=1) const
| per-element matrix multiplication by means of matrix expressions
MatExpr | mul (const MatExpr &m, double scale=1) const
| operator CvMat () const
| converts header to CvMat; no data is copied
| operator CvMatND () const
| converts header to CvMatND; no data is copied
| operator IplImage () const
| converts header to IplImage; no data is copied
template<typename _Tp , int m, int n>
| operator Matx< _Tp, m, n > () const
template<typename _Tp , int n>
| operator Vec< _Tp, n > () const
template<typename _Tp >
| operator vector< _Tp > () const
Mat | operator() (Range rowRange, Range colRange) const
| extracts a rectangular sub-matrix
Mat | operator() (const Rect &roi) const
Mat | operator() (const Range *ranges) const
Mat & | operator= (const Scalar &s)
| sets every matrix element to s
Mat & | operator= (const Mat &m)
| assignment operators
Mat & | operator= (const MatExpr &expr)
void | pop_back (size_t nelems=1)
| removes several hyper-planes from bottom of the matrix
template<typename _Tp , int n>
_Tp * | ptr (const Vec< int, n > &idx)
template<typename _Tp >
const _Tp * | ptr (int i0=0) const
template<typename _Tp >
const _Tp * | ptr (int i0, int i1) const
const uchar * | ptr (int i0, int i1, int i2) const
template<typename _Tp >
const _Tp * | ptr (const int *idx) const
template<typename _Tp >
const _Tp * | ptr (int i0, int i1, int i2) const
uchar * | ptr (int i0, int i1)
| returns pointer to (i0,i1) submatrix along the dimensions #0 and #1
const uchar * | ptr (int i0, int i1) const
template<typename _Tp , int n>
const _Tp * | ptr (const Vec< int, n > &idx) const
uchar * | ptr (int i0=0)
| returns pointer to i0-th submatrix along the dimension #0
const uchar * | ptr (int i0=0) const
template<typename _Tp >
_Tp * | ptr (const int *idx)
template<typename _Tp >
_Tp * | ptr (int i0=0)
| template version of the above method
template<int n>
uchar * | ptr (const Vec< int, n > &idx)
template<typename _Tp >
_Tp * | ptr (int i0, int i1)
uchar * | ptr (int i0, int i1, int i2)
| returns pointer to (i0,i1,i3) submatrix along the dimensions #0, #1, #2
template<int n>
const uchar * | ptr (const Vec< int, n > &idx) const
const uchar * | ptr (const int *idx) const
| returns read-only pointer to the matrix element
uchar * | ptr (const int *idx)
| returns pointer to the matrix element
template<typename _Tp >
_Tp * | ptr (int i0, int i1, int i2)
void | push_back (const Mat &m)
template<typename _Tp >
void | push_back (const Mat_< _Tp > &elem)
template<typename _Tp >
void | push_back (const _Tp &elem)
| adds element to the end of 1d matrix (or possibly multiple elements when _Tp=Mat)
void | push_back_ (const void *elem)
| internal function
void | release ()
| decreases reference counter;
void | reserve (size_t sz)
| reserves enough space to fit sz hyper-planes
Mat | reshape (int _cn, int _newndims, const int *_newsz) const
Mat | reshape (int _cn, int _rows=0) const
| creates alternative matrix header for the same data, with different
void | resize (size_t sz, const Scalar &s)
| resizes matrix to the specified number of hyper-planes; initializes the newly added elements
void | resize (size_t sz)
| resizes matrix to the specified number of hyper-planes
Mat | row (int y) const
| returns a new matrix header for the specified row
Mat | rowRange (const Range &r) const
Mat | rowRange (int startrow, int endrow) const
| ... for the specified row span
Mat & | setTo (const Scalar &s, const Mat &mask=Mat())
| sets some of the matrix elements to s, according to the mask
size_t | step1 (int i=0) const
| returns step/elemSize1()
MatExpr | t () const
| matrix transposition by means of matrix expressions
size_t | total () const
| returns the total number of matrix elements
int | type () const
| returns element type, similar to CV_MAT_TYPE(cvmat->type)
| ~Mat ()
| destructor - calls release()

## Static Public Member Functions

static Mat | diag (const Mat &d)
| constructs a square diagonal matrix which main diagonal is vector "d"
static MatExpr | eye (int rows, int cols, int type)
static MatExpr | eye (Size size, int type)
static MatExpr | ones (int ndims, const int *sz, int type)
static MatExpr | ones (int rows, int cols, int type)
static MatExpr | ones (Size size, int type)
static MatExpr | zeros (int ndims, const int *sz, int type)
static MatExpr | zeros (int rows, int cols, int type)
| Matlab-style matrix initialization.
static MatExpr | zeros (Size size, int type)

## Public Attributes

MatAllocator * | allocator
| custom allocator
int | cols
uchar * | data
| pointer to the data
uchar * | dataend
uchar * | datalimit
uchar * | datastart
| helper fields used in locateROI and adjustROI
int | dims
| the matrix dimensionality, >= 2
int | flags
int * | refcount
| pointer to the reference counter;
int | rows
| the number of rows and columns or (-1, -1) when the matrix has more than 2 dimensions
MSize | size
MStep | step

## Detailed Description

The n-dimensional matrix class.

The class represents an n-dimensional dense numerical array that can act as a matrix, image, optical flow map, 3-focal tensor etc. It is very similar to CvMat and CvMatND types from earlier versions of OpenCV, and similarly to those types, the matrix can be multi-channel. It also fully supports ROI mechanism.

There are many different ways to create cv::Mat object. Here are the some popular ones:

- using cv::Mat::create(nrows, ncols, type) method or the similar constructor cv::Mat::Mat(nrows, ncols, type[, fill_value]) constructor. A new matrix of the specified size and specifed type will be allocated. "type" has the same meaning as in cvCreateMat function, e.g. CV_8UC1 means 8-bit single-channel matrix, CV_32FC2 means 2-channel (i.e. complex) floating-point matrix etc:

           // make 7x7 complex matrix filled with 1+3j.
           cv::Mat M(7,7,CV_32FC2,Scalar(1,3));
           // and now turn M to 100x60 15-channel 8-bit matrix.
           // The old content will be deallocated
           M.create(100,60,CV_8UC(15));

  As noted in the introduction of this chapter, Mat::create() will only allocate a new matrix when the current matrix dimensionality or type are different from the specified.

- by using a copy constructor or assignment operator, where on the right side it can be a matrix or expression, see below. Again, as noted in the introduction, matrix assignment is O(1) operation because it only copies the header and increases the reference counter. cv::Mat::clone() method can be used to get a full (a.k.a. deep) copy of the matrix when you need it.

- by constructing a header for a part of another matrix. It can be a single row, single column, several rows, several columns, rectangular region in the matrix (called a minor in algebra) or a diagonal. Such operations are also O(1), because the new header will reference the same data. You can actually modify a part of the matrix using this feature, e.g.

           // add 5-th row, multiplied by 3 to the 3rd row
           M.row(3) = M.row(3) + M.row(5)*3;

           // now copy 7-th column to the 1-st column
           // M.col(1) = M.col(7); // this will not work
           Mat M1 = M.col(1);
           M.col(7).copyTo(M1);

           // create new 320x240 image
           cv::Mat img(Size(320,240),CV_8UC3);
           // select a roi
           cv::Mat roi(img, Rect(10,10,100,100));
           // fill the ROI with (0,255,0) (which is green in RGB space);
           // the original 320x240 image will be modified
           roi = Scalar(0,255,0);

  Thanks to the additional cv::Mat::datastart and cv::Mat::dataend members, it is possible to compute the relative sub-matrix position in the main "container" matrix using cv::Mat::locateROI():

           Mat A = Mat::eye(10, 10, CV_32S);
           // extracts A columns, 1 (inclusive) to 3 (exclusive).
           Mat B = A(Range::all(), Range(1, 3));
           // extracts B rows, 5 (inclusive) to 9 (exclusive).
           // that is, C ~ A(Range(5, 9), Range(1, 3))
           Mat C = B(Range(5, 9), Range::all());
           Size size; Point ofs;
           C.locateROI(size, ofs);
           // size will be (width=10,height=10) and the ofs will be (x=1, y=5)

  As in the case of whole matrices, if you need a deep copy, use cv::Mat::clone() method of the extracted sub-matrices.

- by making a header for user-allocated-data. It can be useful for

  1. processing "foreign" data using OpenCV (e.g. when you implement a DirectShow filter or a processing module for gstreamer etc.), e.g.

                  void process_video_frame(const unsigned char* pixels,
                                           int width, int height, int step)
                  {
                     cv::Mat img(height, width, CV_8UC3, pixels, step);
                     cv::GaussianBlur(img, img, cv::Size(7,7), 1.5, 1.5);
                  }

  2. for quick initialization of small matrices and/or super-fast element access

                  double m[3][3] = {{a, b, c}, {d, e, f}, {g, h, i}};
                  cv::Mat M = cv::Mat(3, 3, CV_64F, m).inv();

  partial yet very common cases of this "user-allocated data" case are conversions from CvMat and IplImage to cv::Mat. For this purpose there are special constructors taking pointers to CvMat or IplImage and the optional flag indicating whether to copy the data or not.

  Backward conversion from cv::Mat to CvMat or IplImage is provided via cast operators cv::Mat::operator CvMat() an cv::Mat::operator IplImage(). The operators do not copy the data.

             IplImage* img = cvLoadImage("greatwave.jpg", 1);
             Mat mtx(img); // convert IplImage* -> cv::Mat
             CvMat oldmat = mtx; // convert cv::Mat -> CvMat
             CV_Assert(oldmat.cols == img->width && oldmat.rows == img->height &&
                 oldmat.data.ptr == (uchar*)img->imageData && oldmat.step == img->widthStep);

- by using MATLAB-style matrix initializers, cv::Mat::zeros(), cv::Mat::ones(), cv::Mat::eye(), e.g.:

         // create a double-precision identity martix and add it to M.
         M += Mat::eye(M.rows, M.cols, CV_64F);

- by using comma-separated initializer:

         // create 3x3 double-precision identity matrix
         Mat M = (Mat_<double>(3,3) << 1, 0, 0, 0, 1, 0, 0, 0, 1);

  here we first call constructor of cv::Mat_ class (that we describe further) with the proper matrix, and then we just put "<<" operator followed by comma-separated values that can be constants, variables, expressions etc. Also, note the extra parentheses that are needed to avoid compiler errors.

Once matrix is created, it will be automatically managed by using reference-counting mechanism (unless the matrix header is built on top of user-allocated data, in which case you should handle the data by yourself). The matrix data will be deallocated when no one points to it; if you want to release the data pointed by a matrix header before the matrix destructor is called, use cv::Mat::release().

The next important thing to learn about the matrix class is element access. Here is how the matrix is stored. The elements are stored in row-major order (row by row). The cv::Mat::data member points to the first element of the first row, cv::Mat::rows contains the number of matrix rows and cv::Mat::cols - the number of matrix columns. There is yet another member, cv::Mat::step that is used to actually compute address of a matrix element. cv::Mat::step is needed because the matrix can be a part of another matrix or because there can some padding space in the end of each row for a proper alignment.

Given these parameters, address of the matrix element M_{ij} is computed as following:

addr(M_{ij})=M.data + M.step*i + j*M.elemSize()

if you know the matrix element type, e.g. it is float, then you can use cv::Mat::at() method:

addr(M_{ij})=&M.at<float>(i,j)

(where & is used to convert the reference returned by cv::Mat::at() to a pointer). if you need to process a whole row of matrix, the most efficient way is to get the pointer to the row first, and then just use plain C operator []:

       // compute sum of positive matrix elements
       // (assuming that M is double-precision matrix)
       double sum=0;
       for(int i = 0; i < M.rows; i++)
       {
           const double* Mi = M.ptr<double>(i);
           for(int j = 0; j < M.cols; j++)
               sum += std::max(Mi[j], 0.);
       }

Some operations, like the above one, do not actually depend on the matrix shape, they just process elements of a matrix one by one (or elements from multiple matrices that are sitting in the same place, e.g. matrix addition). Such operations are called element-wise and it makes sense to check whether all the input/output matrices are continuous, i.e. have no gaps in the end of each row, and if yes, process them as a single long row:

       // compute sum of positive matrix elements, optimized variant
       double sum=0;
       int cols = M.cols, rows = M.rows;
       if(M.isContinuous())
       {
           cols *= rows;
           rows = 1;
       }
       for(int i = 0; i < rows; i++)
       {
           const double* Mi = M.ptr<double>(i);
           for(int j = 0; j < cols; j++)
               sum += std::max(Mi[j], 0.);
       }

in the case of continuous matrix the outer loop body will be executed just once, so the overhead will be smaller, which will be especially noticeable in the case of small matrices.

Finally, there are STL-style iterators that are smart enough to skip gaps between successive rows:

       // compute sum of positive matrix elements, iterator-based variant
       double sum=0;
       MatConstIterator_<double> it = M.begin<double>(), it_end = M.end<double>();
       for(; it != it_end; ++it)
           sum += std::max(*it, 0.);

The matrix iterators are random-access iterators, so they can be passed to any STL algorithm, including std::sort().

## Member Enumeration Documentation

anonymous enum

Enumerator:

  MAGIC_VAL |
  AUTO_STEP |
  CONTINUOUS_FLAG |
  SUBMATRIX_FLAG |

## Constructor & Destructor Documentation

cv::Mat::Mat | ( | ) | `[inline]`

default constructor

cv::Mat::Mat | ( | int | _rows,
|  | int | _cols,
|  | int | _type
| ) |  | `[inline]`

constructs 2D matrix of the specified size and type

cv::Mat::Mat | ( | Size | _size,
|  | int | _type
| ) |  | `[inline]`

cv::Mat::Mat | ( | int | _rows,
|  | int | _cols,
|  | int | _type,
|  | const Scalar & | _s
| ) |  | `[inline]`

constucts 2D matrix and fills it with the specified value _s.

cv::Mat::Mat | ( | Size | _size,
|  | int | _type,
|  | const Scalar & | _s
| ) |  | `[inline]`

cv::Mat::Mat | ( | int | _ndims,
|  | const int * | _sizes,
|  | int | _type
| ) |  | `[inline]`

constructs n-dimensional matrix

cv::Mat::Mat | ( | int | _ndims,
|  | const int * | _sizes,
|  | int | _type,
|  | const Scalar & | _s
| ) |  | `[inline]`

cv::Mat::Mat | ( | const Mat & | m ) | `[inline]`

copy constructor

cv::Mat::Mat | ( | int | _rows,
|  | int | _cols,
|  | int | _type,
|  | void * | _data,
|  | size_t | _step = `AUTO_STEP`
| ) |  | `[inline]`

constructor for matrix headers pointing to user-allocated data

cv::Mat::Mat | ( | Size | _size,
|  | int | _type,
|  | void * | _data,
|  | size_t | _step = `AUTO_STEP`
| ) |  | `[inline]`

cv::Mat::Mat | ( | int | _ndims,
|  | const int * | _sizes,
|  | int | _type,
|  | void * | _data,
|  | const size_t * | _steps = `0`
| ) |  |

cv::Mat::Mat | ( | const Mat & | m,
|  | const Range & | rowRange,
|  | const Range & | colRange = `Range::all()`
| ) |  |

creates a matrix header for a part of the bigger matrix

cv::Mat::Mat | ( | const Mat & | m,
|  | const Rect & | roi
| ) |  |

cv::Mat::Mat | ( | const Mat & | m,
|  | const Range * | ranges
| ) |  |

cv::Mat::Mat | ( | const CvMat * | m,
|  | bool | copyData = `false`
| ) |  | `[inline]`

converts old-style CvMat to the new matrix; the data is not copied by default

cv::Mat::Mat | ( | const CvMatND * | m,
|  | bool | copyData = `false`
| ) |  |

converts old-style CvMatND to the new matrix; the data is not copied by default

cv::Mat::Mat | ( | const IplImage * | img,
|  | bool | copyData = `false`
| ) |  |

converts old-style IplImage to the new matrix; the data is not copied by default

template<typename _Tp >

cv::Mat::Mat | ( | const vector< _Tp > & | vec,
|  | bool | copyData = `false`
| ) |  | `[inline, explicit]`

builds matrix from std::vector with or without copying the data

template<typename _Tp , int n>

cv::Mat::Mat | ( | const Vec< _Tp, n > & | vec,
|  | bool | copyData = `true`
| ) |  | `[inline, explicit]`

builds matrix from cv::Vec; the data is copied by default

template<typename _Tp , int m, int n>

cv::Mat::Mat | ( | const Matx< _Tp, m, n > & | mtx,
|  | bool | copyData = `true`
| ) |  | `[inline, explicit]`

builds matrix from cv::Matx; the data is copied by default

template<typename _Tp >

cv::Mat::Mat | ( | const Point_< _Tp > & | pt,
|  | bool | copyData = `true`
| ) |  | `[inline, explicit]`

builds matrix from a 2D point

template<typename _Tp >

cv::Mat::Mat | ( | const Point3_< _Tp > & | pt,
|  | bool | copyData = `true`
| ) |  | `[inline, explicit]`

builds matrix from a 3D point

template<typename _Tp >

cv::Mat::Mat | ( | const MatCommaInitializer_< _Tp > & | commaInitializer ) | `[inline, explicit]`

builds matrix from comma initializer

cv::Mat::~Mat | ( | ) | `[inline]`

destructor - calls release()

## Member Function Documentation

void cv::Mat::addref | ( | ) | `[inline]`

increases the reference counter; use with care to avoid memleaks

Mat& cv::Mat::adjustROI | ( | int | dtop,
|  | int | dbottom,
|  | int | dleft,
|  | int | dright
| ) |  |

moves/resizes the current matrix ROI inside the parent matrix.

Reimplemented in cv::Mat_< _Tp >.

void cv::Mat::assignTo | ( | Mat & | m,
|  | int | type = `-1`
| ) |  | const`[inline]`

template<typename _Tp >

_Tp & cv::Mat::at | ( | int | i0 = `0` ) | `[inline]`

the same as above, with the pointer dereferencing

template<typename _Tp >

const _Tp & cv::Mat::at | ( | int | i0 = `0` ) | const`[inline]`

template<typename _Tp >

const _Tp & cv::Mat::at | ( | Point | pt ) | const`[inline]`

template<typename _Tp >

_Tp & cv::Mat::at | ( | int | i0,
|  | int | i1
| ) |  | `[inline]`

template<typename _Tp >

const _Tp & cv::Mat::at | ( | int | i0,
|  | int | i1
| ) |  | const`[inline]`

template<typename _Tp >

_Tp & cv::Mat::at | ( | int | i0,
|  | int | i1,
|  | int | i2
| ) |  | `[inline]`

template<typename _Tp >

const _Tp & cv::Mat::at | ( | int | i0,
|  | int | i1,
|  | int | i2
| ) |  | const`[inline]`

template<typename _Tp >

_Tp & cv::Mat::at | ( | const int * | idx ) | `[inline]`

template<typename _Tp >

const _Tp & cv::Mat::at | ( | const int * | idx ) | const`[inline]`

template<typename _Tp , int n>

_Tp& cv::Mat::at | ( | const Vec< int, n > & | idx ) |

template<typename _Tp , int n>

const _Tp& cv::Mat::at | ( | const Vec< int, n > & | idx ) | const

template<typename _Tp >

_Tp & cv::Mat::at | ( | Point | pt ) | `[inline]`

special versions for 2D arrays (especially convenient for referencing image pixels)

template<typename _Tp >

MatIterator_< _Tp > cv::Mat::begin | ( | ) | `[inline]`

template methods for iteration over matrix elements.

Reimplemented in cv::Mat_< _Tp >.

template<typename _Tp >

MatConstIterator_< _Tp > cv::Mat::begin | ( | ) | const`[inline]`

Reimplemented in cv::Mat_< _Tp >.

int cv::Mat::channels | ( | ) | const`[inline]`

returns element type, similar to CV_MAT_CN(cvmat->type)

Reimplemented in cv::Mat_< _Tp >.

int cv::Mat::checkVector | ( | int | elemChannels,
|  | int | depth = `-1`,
|  | bool | requireContinuous = `true`
| ) |  | const

returns N if the matrix is 1-channel (N x ptdim) or ptdim-channel (1 x N) or (N x 1); negative number otherwise

Mat cv::Mat::clone | ( | ) | const`[inline]`

returns deep copy of the matrix, i.e. the data is copied

Reimplemented in cv::Mat_< _Tp >.

Mat cv::Mat::col | ( | int | x ) | const`[inline]`

returns a new matrix header for the specified column

Reimplemented in cv::Mat_< _Tp >.

Mat cv::Mat::colRange | ( | const Range & | r ) | const`[inline]`

Mat cv::Mat::colRange | ( | int | startcol,
|  | int | endcol
| ) |  | const`[inline]`

... for the specified column span

void cv::Mat::convertTo | ( | Mat & | m,
|  | int | rtype,
|  | double | alpha = `1`,
|  | double | beta = `0`
| ) |  | const

converts matrix to another datatype with optional scalng. See cvConvertScale.

void cv::Mat::copySize | ( | const Mat & | m ) |

internal use function; properly re-allocates _size, _step arrays

void cv::Mat::copyTo | ( | Mat & | m ) | const

copies the matrix content to "m".

template<typename _Tp >

void cv::Mat::copyTo | ( | vector< _Tp > & | v ) | const`[inline]`

void cv::Mat::copyTo | ( | Mat & | m,
|  | const Mat & | mask
| ) |  | const

copies those matrix elements to "m" that are marked with non-zero mask elements.

void cv::Mat::create | ( | int | _rows,
|  | int | _cols,
|  | int | _type
| ) |  | `[inline]`

allocates new matrix data unless the matrix already has specified size and type.

void cv::Mat::create | ( | int | _ndims,
|  | const int * | _sizes,
|  | int | _type
| ) |  |

void cv::Mat::create | ( | Size | _size,
|  | int | _type
| ) |  | `[inline]`

Mat cv::Mat::cross | ( | const Mat & | m ) | const

computes cross-product of 2 3D vectors

void cv::Mat::deallocate | ( | ) |

deallocates the matrix data

int cv::Mat::depth | ( | ) | const`[inline]`

returns element type, similar to CV_MAT_DEPTH(cvmat->type)

Reimplemented in cv::Mat_< _Tp >.

Mat cv::Mat::diag | ( | int | d = `0` ) | const

... for the specified diagonal

Reimplemented in cv::Mat_< _Tp >.

Mat cv::Mat::diag | ( | const Mat & | d ) | `[inline, static]`

constructs a square diagonal matrix which main diagonal is vector "d"

double cv::Mat::dot | ( | const Mat & | m ) | const

computes dot-product

size_t cv::Mat::elemSize | ( | ) | const`[inline]`

returns element size in bytes,

Reimplemented in cv::Mat_< _Tp >.

size_t cv::Mat::elemSize1 | ( | ) | const`[inline]`

returns the size of element channel in bytes.

Reimplemented in cv::Mat_< _Tp >.

bool cv::Mat::empty | ( | ) | const`[inline]`

returns true if matrix data is NULL

template<typename _Tp >

MatIterator_< _Tp > cv::Mat::end | ( | ) | `[inline]`

Reimplemented in cv::Mat_< _Tp >.

template<typename _Tp >

MatConstIterator_< _Tp > cv::Mat::end | ( | ) | const`[inline]`

Reimplemented in cv::Mat_< _Tp >.

static MatExpr cv::Mat::eye | ( | int | rows,
|  | int | cols,
|  | int | type
| ) |  | `[static]`

static MatExpr cv::Mat::eye | ( | Size | size,
|  | int | type
| ) |  | `[static]`

MatExpr cv::Mat::inv | ( | int | method = `DECOMP_LU` ) | const

matrix inversion by means of matrix expressions

bool cv::Mat::isContinuous | ( | ) | const`[inline]`

returns true iff the matrix data is continuous

bool cv::Mat::isSubmatrix | ( | ) | const`[inline]`

returns true if the matrix is a submatrix of another matrix

void cv::Mat::locateROI | ( | Size & | wholeSize,
|  | Point & | ofs
| ) |  | const

locates matrix header within a parent matrix. See below

MatExpr cv::Mat::mul | ( | const Mat & | m,
|  | double | scale = `1`
| ) |  | const

per-element matrix multiplication by means of matrix expressions

MatExpr cv::Mat::mul | ( | const MatExpr & | m,
|  | double | scale = `1`
| ) |  | const

static MatExpr cv::Mat::ones | ( | int | ndims,
|  | const int * | sz,
|  | int | type
| ) |  | `[static]`

static MatExpr cv::Mat::ones | ( | int | rows,
|  | int | cols,
|  | int | type
| ) |  | `[static]`

static MatExpr cv::Mat::ones | ( | Size | size,
|  | int | type
| ) |  | `[static]`

cv::Mat::operator CvMat | ( | ) | const`[inline]`

converts header to CvMat; no data is copied

cv::Mat::operator CvMatND | ( | ) | const

converts header to CvMatND; no data is copied

cv::Mat::operator IplImage | ( | ) | const

converts header to IplImage; no data is copied

template<typename _Tp , int m, int n>

cv::Mat::operator Matx< _Tp, m, n > | ( | ) | const`[inline]`

template<typename _Tp , int n>

cv::Mat::operator Vec< _Tp, n > | ( | ) | const`[inline]`

template<typename _Tp >

cv::Mat::operator vector< _Tp > | ( | ) | const`[inline]`

Reimplemented in cv::Mat_< _Tp >.

Mat cv::Mat::operator() | ( | Range | rowRange,
|  | Range | colRange
| ) |  | const`[inline]`

extracts a rectangular sub-matrix

Mat cv::Mat::operator() | ( | const Rect & | roi ) | const`[inline]`

Reimplemented in cv::Mat_< _Tp >.

Mat cv::Mat::operator() | ( | const Range * | ranges ) | const`[inline]`

Reimplemented in cv::Mat_< _Tp >.

Mat & cv::Mat::operator= | ( | const MatExpr & | expr ) | `[inline]`

Reimplemented in cv::Mat_< _Tp >.

Mat& cv::Mat::operator= | ( | const Scalar & | s ) |

sets every matrix element to s

Mat & cv::Mat::operator= | ( | const Mat & | m ) | `[inline]`

assignment operators

Reimplemented in cv::Mat_< _Tp >.

void cv::Mat::pop_back | ( | size_t | nelems = `1` ) |

removes several hyper-planes from bottom of the matrix

template<typename _Tp >

const _Tp* cv::Mat::ptr | ( | int | i0,
|  | int | i1
| ) |  | const

template<typename _Tp >

_Tp* cv::Mat::ptr | ( | int | i0 = `0` ) |

template version of the above method

const uchar * cv::Mat::ptr | ( | const int * | idx ) | const`[inline]`

returns read-only pointer to the matrix element

uchar * cv::Mat::ptr | ( | const int * | idx ) | `[inline]`

returns pointer to the matrix element

const uchar * cv::Mat::ptr | ( | int | i0,
|  | int | i1,
|  | int | i2
| ) |  | const`[inline]`

uchar * cv::Mat::ptr | ( | int | i0,
|  | int | i1
| ) |  | `[inline]`

returns pointer to (i0,i1) submatrix along the dimensions #0 and #1

template<typename _Tp , int n>

const _Tp* cv::Mat::ptr | ( | const Vec< int, n > & | idx ) | const

const uchar * cv::Mat::ptr | ( | int | i0,
|  | int | i1
| ) |  | const`[inline]`

_Tp * cv::Mat::ptr | ( | int | i0 = `0` ) | `[inline]`

returns pointer to i0-th submatrix along the dimension #0

const _Tp * cv::Mat::ptr | ( | int | i0 = `0` ) | const`[inline]`

uchar * cv::Mat::ptr | ( | int | i0,
|  | int | i1,
|  | int | i2
| ) |  | `[inline]`

returns pointer to (i0,i1,i3) submatrix along the dimensions #0, #1, #2

template<typename _Tp >

const _Tp* cv::Mat::ptr | ( | int | i0,
|  | int | i1,
|  | int | i2
| ) |  | const

template<int n>

uchar* cv::Mat::ptr | ( | const Vec< int, n > & | idx ) |

template<int n>

const uchar* cv::Mat::ptr | ( | const Vec< int, n > & | idx ) | const

template<typename _Tp >

_Tp* cv::Mat::ptr | ( | int | i0,
|  | int | i1
| ) |  |

template<typename _Tp >

_Tp* cv::Mat::ptr | ( | const int * | idx ) |

template<typename _Tp , int n>

_Tp* cv::Mat::ptr | ( | const Vec< int, n > & | idx ) |

template<typename _Tp >

_Tp* cv::Mat::ptr | ( | int | i0,
|  | int | i1,
|  | int | i2
| ) |  |

template<typename _Tp >

const _Tp* cv::Mat::ptr | ( | const int * | idx ) | const

template<typename _Tp >

const _Tp* cv::Mat::ptr | ( | int | i0 = `0` ) | const

template<typename _Tp >

void cv::Mat::push_back | ( | const Mat_< _Tp > & | elem ) | `[inline]`

void cv::Mat::push_back | ( | const Mat & | m ) |

template<typename _Tp >

void cv::Mat::push_back | ( | const _Tp & | elem ) | `[inline]`

adds element to the end of 1d matrix (or possibly multiple elements when _Tp=Mat)

void cv::Mat::push_back_ | ( | const void * | elem ) |

internal function

void cv::Mat::release | ( | ) | `[inline]`

decreases reference counter;

void cv::Mat::reserve | ( | size_t | sz ) |

reserves enough space to fit sz hyper-planes

Mat cv::Mat::reshape | ( | int | _cn,
|  | int | _rows = `0`
| ) |  | const

creates alternative matrix header for the same data, with different

Mat cv::Mat::reshape | ( | int | _cn,
|  | int | _newndims,
|  | const int * | _newsz
| ) |  | const

void cv::Mat::resize | ( | size_t | sz,
|  | const Scalar & | s
| ) |  |

resizes matrix to the specified number of hyper-planes; initializes the newly added elements

void cv::Mat::resize | ( | size_t | sz ) |

resizes matrix to the specified number of hyper-planes

Mat cv::Mat::row | ( | int | y ) | const`[inline]`

returns a new matrix header for the specified row

Reimplemented in cv::Mat_< _Tp >.

Mat cv::Mat::rowRange | ( | int | startrow,
|  | int | endrow
| ) |  | const`[inline]`

... for the specified row span

Mat cv::Mat::rowRange | ( | const Range & | r ) | const`[inline]`

Mat& cv::Mat::setTo | ( | const Scalar & | s,
|  | const Mat & | mask = `Mat()`
| ) |  |

sets some of the matrix elements to s, according to the mask

size_t cv::Mat::step1 | ( | int | i = `0` ) | const`[inline]`

returns step/elemSize1()

Reimplemented in cv::Mat_< _Tp >.

MatExpr cv::Mat::t | ( | ) | const

matrix transposition by means of matrix expressions

size_t cv::Mat::total | ( | ) | const`[inline]`

returns the total number of matrix elements

int cv::Mat::type | ( | ) | const`[inline]`

returns element type, similar to CV_MAT_TYPE(cvmat->type)

Reimplemented in cv::Mat_< _Tp >.

static MatExpr cv::Mat::zeros | ( | int | rows,
|  | int | cols,
|  | int | type
| ) |  | `[static]`

Matlab-style matrix initialization.

static MatExpr cv::Mat::zeros | ( | int | ndims,
|  | const int * | sz,
|  | int | type
| ) |  | `[static]`

static MatExpr cv::Mat::zeros | ( | Size | size,
|  | int | type
| ) |  | `[static]`

## Member Data Documentation

MatAllocator* cv::Mat::allocator

custom allocator

int cv::Mat::cols

uchar* cv::Mat::data

pointer to the data

uchar* cv::Mat::dataend

uchar* cv::Mat::datalimit

uchar* cv::Mat::datastart

helper fields used in locateROI and adjustROI

int cv::Mat::dims

the matrix dimensionality, >= 2

int cv::Mat::flags

includes several bit-fields:

- the magic signature
- continuity flag
- depth
- number of channels

int* cv::Mat::refcount

pointer to the reference counter;

int cv::Mat::rows

the number of rows and columns or (-1, -1) when the matrix has more than 2 dimensions

MSize cv::Mat::size

MStep cv::Mat::step

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

- /usr/obj/OpenCV-2.2.0/OpenCV-2.2.0/modules/core/include/opencv2/core/core.hpp
- /usr/obj/OpenCV-2.2.0/OpenCV-2.2.0/modules/core/include/opencv2/core/mat.hpp

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