title: Expected Ptr<cv::UMat> for argument 'src'
body: <p>I have to convert a video to gray format first, then to hsv but I get this error :</p>
  <pre><code>Traceback (most recent call last):
    File &quot;c:/Users/eycan/Desktop/serittakip.py&quot;, line 8, in &lt;module&gt;
      im = cv2.cvtColor(vid, cv2.COLOR_BGR2GRAY) # grayscale kopya
  TypeError: Expected Ptr&lt;cv::UMat&gt; for argument 'src'
  </code></pre>
  <p>My code:</p>
  <pre><code>import cv2
  import numpy as np
  
  vid = cv2.VideoCapture(&quot;C:\\Users\\eycan\\Desktop\\serit\\yol.mp4&quot;)
  
  while 1:    #frame cektıgımız ıcın whıle dongusune soktuk resım olsaydı boyle olmazdı
      _,frame = vid.read()
      im = cv2.cvtColor(vid, cv2.COLOR_BGR2GRAY) # grayscale kopya
      vid = cv2.cvtColor(frame,cv2.COLOR_BGR2HSV) #bgr dan hsv ye donusturduk
  
      lower_white = np.array([0, 0, 212])
      upper_white = np.array([131, 255, 255])
  
      mask = cv2.inRange(vid,lower_white,upper_white)
      cv2.imshow(&quot;Frame&quot;,frame)
      cv2.imshow(&quot;MASK&quot;,mask)
  </code></pre>
  <p>Pls help :/</p>