[[nodiscard]] is defined in C++17.
There is fallback alias for modern GCC / Clang compilers.

Add overloaded cv::PCACompute() that returns also the eigenvalues. Useful for Java and Python OpenCV where PCA is not available.

Function is very fast, so 0.000 ms results are useless.
1000 runs requires 25ms on i7-6700K.

Fixed Matx::solve function for non-square matrixes (#11904)

      - Changing the contrast and brightness of an image!
      - Operations with images

Temporary object lifetime must be greater than pointer usage.

use vload3 for half3 or float3 input vector reading,
also check read position to see if it exceed input width
Signed-off-by: Li Peng <peng.li@intel.com>

Add a note in the documentation about Mat::ones and mat::eye. With multi-channels type (e.g. CV_8UC3), only the first channel is treated.

"custom layers" feature will not work properly in these builds.