title: delete pixel from the raster image with specific range value
body: <p><strong>update :</strong>
  any idea how to delete pixel from specific range value raster image with 
  using <code>numpy/scipy</code> or <code>gdal</code>?</p>
  
  <p><strong>or how to can create new raster with some class using raster calculation expressions</strong>(better)</p>
  
  <p>for example i have a raster image with the 
  5 class : </p>
  
  <pre><code>1. 0-100 
  2. 100-200 
  3. 200-300 
  4. 300-500 
  5. 500-1000 
  </code></pre>
  
  <p>and i want to delete class 1 range value 
  or maybe class <code>1,2,4,5</code> </p>
  
  <p>i begin with this script :</p>
  
  <pre><code>import numpy as np
  from osgeo import gdal
  ds = gdal.Open("raster3.tif")
  myarray = np.array(ds.GetRasterBand(1).ReadAsArray())
  #print myarray.shape
  #print myarray.size
  #print myarray
  new=np.delete(myarray[::2], 1)
  </code></pre>
  
  <p>but i cant to complete</p>
  
  <p>the image
  <a href="http://i.stack.imgur.com/S4bk4.jpg" rel="nofollow">White in class 5 and black class 1</a></p>