 | 1 | initial version |
Say I have an allocated cv::Mat img of size 100x100. Now I call img.create(50,50,img.type()).
Since the type is the same, there is, obviously, enough memory already allocated, and all that's needed is to set a proper "ROI" on the existing Mat.
Does create() actually do this, or does it release and re-allocate since the size is different (50x50 vs. 100x100)?
| | 2 | No.2 Revision |
Say I have an allocated cv::Mat img of size 100x100. Now I call img.create(50,50,img.type()).
Since the type is the same, there is, obviously, enough memory already allocated, and all that's needed is to set a proper "ROI" on the existing Mat.
Does create() actually do this, or does it release and re-allocate since the size is different (50x50 vs. 100x100)?
An std::vector<> uses the same stratgy. You can resize() it to 0, but it will still keep the internal buffer available so that growing again later, e.g. with push_back() does not reallocate.
The same thing could be done with ROIs.
