title: PDF to tiff ImageMagick problem
body: <p>I'm trying to convert pdfs to tiff images for following OCR. I use "-density 300x300 -depth 8" as parameters. 
  The first problem is that from 500 KB pdf file i get 72 MB tiff file.
  The second problem is bad quality of resulting image causing OCR failing.
  Here you can see it yourself.
  Adobe acrobat reader generated (printed) tiff image:
  <img src="https://i.stack.imgur.com/PbPjL.png" alt="enter image description here"></p>
  
  <p>ImageMaggick tiff image:
  <img src="https://i.stack.imgur.com/pv5hR.png" alt="enter image description here"></p>
  
  <p>The difference is huge.
  How can i get as good as Adobe generated image using ImageMaggick?
  Not tiff neccesary, other formats also will be good.</p>
  
  <p>UPD: i've found 'antialias' option. Now it's much more better. 
  But still OCR result not so accurate as for Adobe version.</p>