title: How to use opencv with cuda support python?
body: <p>I found example of cuda accelerated opencv python code in official opencv github repository. 
  <a href="https://github.com/opencv/opencv/blob/master/modules/python/test/test_cuda.py" rel="nofollow noreferrer">test_cuda.py</a></p>
  
  <pre><code>cuMat1 = cv.cuda_GpuMat()
  cuMat2 = cv.cuda_GpuMat()
  cuMat1.upload(npMat1)
  cuMat2.upload(npMat2)
  
  cuMat1 = cv.cuda.cvtColor(cuMat1, cv.COLOR_RGB2GRAY)
  cuMat2 = cv.cuda.cvtColor(cuMat2, cv.COLOR_RGB2GRAY)
  </code></pre>
  
  <p>But I found that module 'cv2.cuda' has no attribute 'cvtColor'.</p>
  
  <p>My opencv build information:</p>
  
  <pre><code>NVIDIA CUDA:                   YES (ver 10.0, CUFFT CUBLAS FAST_MATH)
  NVIDIA GPU arch:             61
  NVIDIA PTX archs:            61
  </code></pre>
  
  <p><a href="https://pastebin.com/U7v12Vhm" rel="nofollow noreferrer">Full build information</a></p>
  
  <p>How to fix it?</p>