title: How to use the convertScaleAbs() function in OpenCV?
body: <p>I am trying to convert an image back to grayscale after applying Sobel filtering on it. I have the following code:</p>
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  import cv2
  
  image = cv2.imread(&quot;train.jpg&quot;)
  img = np.array(image, dtype=np.uint8)
  
  #convert to greyscale
  img_grey = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
  
  #remove noise
  img_smooth = cv2.GaussianBlur(img_grey, (13,13), 0)
  
  sobely = cv2.Sobel(img_smooth,cv2.CV_64F,0,1,ksize=9)
  </code></pre>
  <p>I want to convert the image <code>sobely</code> back to greyscale using the convertScaleAbs() function.</p>
  <p>I know that the function takes a source (the image to be converted to grayscale) and destination array as arguments, but I am not sure what is the best way to go about creating the destination array.</p>
  <p>Any insights are appreciated.</p>