title: sys.argv[1]. IndexError: list index out of range
body: <p>I want to find out the similarity between 2 images but I'm getting this error</p>
  
  <pre><code>if __name__ == '__main__':
    img1 = sys.argv[0]
    img2 = sys.argv[1]
  
    # Create image objects
    image1 = Image.open(img1)
    image2 = Image.open(img2)
  
    # Test pixel by pixel
    get_image_pixel_similarity(img1, img2)
  </code></pre>
  
  <blockquote>
    <p>sys.argv[1]. IndexError: list index out of range</p>
  </blockquote>
  
  <p>How can I sort out my problem?</p>