title: when i use imagemagic montage by im4java,the -tile row x clos option throws a file unable to open exception
body: <p>./magick -version
  Version: ImageMagick 7.0.8-46 Q16 x86_64 2019-05-19 
  <a href="https://imagemagick.org" rel="nofollow noreferrer">https://imagemagick.org</a>
  Copyright: © 1999-2019 ImageMagick Studio LLC
  License: <a href="https://imagemagick.org/script/license.php" rel="nofollow noreferrer">https://imagemagick.org/script/license.php</a>
  Features: Cipher DPC HDRI 
  Delegates (built-in): bzlib freetype jng jpeg png tiff xml zlib</p>
  
  <p>im4java-1.4.0.jar</p>
  
  <p>when i run the command,it throws a exception</p>
  
  <pre><code>org.im4java.core.CommandException: org.im4java.core.CommandException: magick: unable to open image ' 9x4': No such file or directory @ error/blob.c/OpenBlob/3497.
      at org.im4java.core.ImageCommand.run(ImageCommand.java:219)
      at dsl.Tools.ImageDealTool.ex(ImageDealTool.java:246)
      at dsl.Tools.ImageDealTool.montage(ImageDealTool.java:122)
      at dsl.Tools.ImageDealService.imageLayout(ImageDealService.java:106)
      at dsl.controller.ImageDealController$2.run(ImageDealController.java:133)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:745)
  Caused by: org.im4java.core.CommandException: magick: unable to open image ' 9x4': No such file or directory @ error/blob.c/OpenBlob/3497.
      at org.im4java.core.ImageCommand.finished(ImageCommand.java:253)
      at org.im4java.process.ProcessStarter.run(ProcessStarter.java:314)
      at org.im4java.core.ImageCommand.run(ImageCommand.java:215)
      ... 7 more
  
  
  
  
  
  files.stream().forEach(s-&gt;{
      if (!s.equals("transparency")) {
        op.addImage(PIC_MODEL_PATH+s+".png");
      }else {
        op.addImage(MODEL_PATH+s+".png");
      }
  });
  op.geometry(+0,+0);
  op.addRawArgs("-geometry","+0+0");
  op.addRawArgs("-background","none");
  op.addRawArgs("-tile",cols+"x"+rows);
  op.addImage(ARRAY_RESULT_PATH+result+".png");
  ImageCommand cmd = new MontageCmd(false);
  cmd.run(op);     
  </code></pre>
  
  <p>why the -tile 9x4 option not work?</p>