title: How to check image quality in opencv?
body: <p>I am kind of new to Image processing and OpenCV. In my project, I am doing OCR. But before that, I want to check quality of image is enough good or not. The library I am using for doing OCR says that image should have more than 300 DPI. As far as I know, DPI is related to printer/scanner.</p>
  
  <p>So what can OpenCV give it to me which is directly proportional to DPI ?</p>