title: What is the difference for sample/resample/scale/resize/adaptive-resize/thumbnail operators in ImageMagick convert?
body: <p>I found multiple ways to change the resolution of an image using <code>convert</code>:</p>
  
  <pre><code>-sample
  -resample
  -scale
  -resize
  -adaptive-resize
  -thumbnail
  </code></pre>
  
  <p>What's the difference of those?</p>
  
  <p>If I need to make various size large picture thumbnail with fixed aspect ratio (cropping needed) -- what's my best choice?</p>