title: cache resources exhausted Imagemagick
body: <p>I'm using Imagemagick on a rails app with Minimagick and I generate some pictogram with it.</p>
  <p>When I launch my process I have this error and I don't find a solution:</p>
  <pre><code>MiniMagick::Error (`convert -limit memory 2GiB -limit map 2GiB -limit   disk 4GiB -background none -fill #000000 -font ttf/SELIS006N.ttf -pointsize 300 label: S public/pictogram_images/RECINTAN-EL-064-layer-1.png` failed with error:
  convert.im6: cache resources exhausted ` S' @ error/cache.c/OpenPixelCache/4078.
  convert.im6: no images defined `public/pictogram_images/RECINTAN-EL-064-layer-1.png' @ error/convert.c/ConvertImageCommand/3044.
  ):
  </code></pre>
  <p>My process is simple, I have some .tff file and each character is a pictogram. I just want to generate all preview of this character in png.</p>