title: C# how to use OpenCV to remove noise of a captcha?
body: <p>I'm trying to learn how to remove noise of a captcha image. I started trying to find patterns in the images.</p>
  
  <p>1) The background are always orange:</p>
  
  <p><a href="https://i.stack.imgur.com/YhpZ3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YhpZ3.png" alt="captcha 1"></a> <a href="https://i.stack.imgur.com/E5fYA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/E5fYA.png" alt="captcha 2"></a> <a href="https://i.stack.imgur.com/8TFtJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8TFtJ.png" alt="captcha 3"></a></p>
  
  <p>2) The font are aways the same and aways are in the same size.</p>
  
  <p><a href="https://i.stack.imgur.com/tz0y8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tz0y8.png" alt="captcha 4"></a></p>
  
  <p>Now its time to try to remove the noise, but in my searches I coudnt understand how to remove noise effectively with the captchas I have.</p>
  
  <p>I'm familiar with C# and I was reading about OpenCV, how can I use it to remove the noise in the images I have?</p>