How to find out what type of a Mat object is with Mat type in OpenCV

Question

I am kind of confused with type   method of Mat object in OpenCV If I have following lines   mat   imread  C  someimage jpg    type   mat type      and type   16  How do I find out what type of mat matrix is  I tried to find the answer in its manual or in a couple of books in vain

User · Answer

I ve added some usability to the function from the answer by  Octopus  for debugging purposes   void MatType  Mat inputMat         int inttype   inputMat type         string r  a      uchar depth   inttype  amp  CV MAT DEPTH MASK      uchar chans   1    inttype  gt  gt  CV CN SHIFT       switch   depth             case CV 8U   r    8U     a    Mat at lt uchar gt  y x    break            case CV 8S   r    8S     a    Mat at lt schar gt  y x    break            case CV 16U  r    16U    a    Mat at lt ushort gt  y x    break           case CV 16S  r    16S    a    Mat at lt short gt  y x    break           case CV 32S  r    32S    a    Mat at lt int gt  y x    break           case CV 32F  r    32F    a    Mat at lt float gt  y x    break           case CV 64F  r    64F    a    Mat at lt double gt  y x    break           default      r    User   a    Mat at lt UKNOWN gt  y x    break                r     C       r     chans  0        cout  lt  lt   Mat is of type    lt  lt  r  lt  lt    and should be accessed with    lt  lt  a  lt  lt  endl

User · Answer

I always use this link to see what type is the number I get with type   LIST OF MAT TYPE IN OPENCV I hope this can help you

User · Answer

Here is a handy function you can use to help with identifying your opencv matrices at runtime  I find it useful for debugging  at least   string type2str int type      string r     uchar depth   type  amp  CV MAT DEPTH MASK    uchar chans   1    type  gt  gt  CV CN SHIFT      switch   depth         case CV 8U   r    8U   break      case CV 8S   r    8S   break      case CV 16U  r    16U   break      case CV 16S  r    16S   break      case CV 32S  r    32S   break      case CV 32F  r    32F   break      case CV 64F  r    64F   break      default      r    User   break         r     C     r     chans  0       return r      If M is a var of type Mat you can call it like so   string ty    type2str  M type      printf  Matrix   s  dx d  n   ty c str    M cols  M rows      Will output data such as   Matrix  8UC3 640x480  Matrix  64FC1 3x2    Its worth noting that there are also Matrix methods Mat  depth   and Mat  channels    This function is just a handy way of getting a human readable interpretation from the combination of those two values whose bits are all stored in the same value

User · Answer

This was answered by a few others but I found a solution that worked really well for me  System out println CvType typeToString yourMat type

User · Answer

For debugging purposes in case you want to look up a raw Mat  type in a debugger     -------- ---- ---- ---- ---- ------ ------ ------ ------             C1   C2   C3   C4   C 5    C 6    C 7    C 8     -------- ---- ---- ---- ---- ------ ------ ------ ------    CV 8U     0    8   16   24     32     40     48     56     CV 8S     1    9   17   25     33     41     49     57     CV 16U    2   10   18   26     34     42     50     58     CV 16S    3   11   19   27     35     43     51     59     CV 32S    4   12   20   28     36     44     52     60     CV 32F    5   13   21   29     37     45     53     61     CV 64F    6   14   22   30     38     46     54     62    -------- ---- ---- ---- ---- ------ ------ ------ ------    So for example  if type   30 then OpenCV data type is CV 64FC4   If type   50 then the OpenCV data type is CV 16UC 7

User · Answer

In OpenCV header  types c h  there are a set of defines which generate these  the format is CV bits U S F C lt number of channels gt  So for example CV 8UC3 means 8 bit unsigned chars  3 colour channels - each of these names map onto an arbitrary integer with the macros in that file   Edit  See  types c h  for example    define CV 8UC3 CV MAKETYPE CV 8U 3   define CV MAKETYPE depth cn   CV MAT DEPTH depth       cn -1   lt  lt  CV CN SHIFT    eg  depth   CV 8U   0 cn   3 CV CN SHIFT   3  CV MAT DEPTH 0    0    cn -1   lt  lt  CV CN SHIFT     3-1   lt  lt  3   2 lt  lt 3   16   So CV 8UC3   16  but you aren t supposed to use this number  just check type      CV 8UC3 if you need to know what type an internal OpenCV array is  Remember OpenCV will convert the jpeg into BGR  or grey scale if you pass  0  to imread  - so it doesn t tell you anything about the original file

[opencv] How to find out what type of a Mat object is with Mat::type() in OpenCV

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