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

by

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 & CV_MAT_DEPTH_MASK;
  uchar chans = 1 + (type >> 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.

More Related Contents:

  1. How to crop a CvMat in OpenCV?
  2. opencv c++ Edge detection to find edge that the top of it is white and the bottom is black
  3. Detect semicircle in OpenCV
  4. How to verify the correctness of calibration of a webcam?
  5. opencv drawing a 2d histogram
  6. How to capture the desktop in OpenCV (ie. turn a bitmap into a Mat)?
  7. Computing x,y coordinate (3D) from image point
  8. Displaying stitched images together without cutoff using warpAffine
  9. Configuring an c++ OpenCV project with Cmake
  10. ‘unresolved external symbol’ error when linking with OpenCV 3.0
  11. sift = cv2.xfeatures2d.SIFT_create() not working even though have contrib installed
  12. How to reduce number of classes in YOLOv3 files?
  13. CMake Error: Variables are set to NOTFOUND
  14. MinAreaRect angles – Unsure about the angle returned
  15. OpenCV / SURF How to generate a image hash / fingerprint / signature out of the descriptors?
  16. Sift implementation with OpenCV 2.2
  17. Why cv2.so missing after opencv installed?
  18. How to load png images with 4 channels?
  19. OpenCV as a static library (cmake options)
  20. Filling gaps in shape edges
  21. Can’t access webcam with OpenCV
  22. cv2.imshow() function is opening a window that always says not responding – python opencv
  23. How to use Bazel to build project uses OpenCV [closed]
  24. OpenCV Mat element types and their sizes
  25. initialize an OpenCV Mat with an 2D array
  26. Are there any fast alternatives to SURF and SIFT for scale-invariant feature extraction?
  27. Superimpose heatmap on a base image OpenCV Python
  28. Q matrix for the reprojectImageTo3D function in opencv
  29. How can I get ellipse coefficient from fitEllipse function of OpenCV?
  30. Preprocessing image for Tesseract OCR with OpenCV

Leave a Comment