title: changing image resolution in Python for a .bmp file
body: <p>I want to change the resolution of the .bmp image in python. ( i.e. the pixel/inch information) . Using PIL, for jpg image, for instance, the following code works fine</p>
  
  <pre><code>import Image 
  im = Image.open("myImg.jpg)
  im.save("output.jpg", dpi = (75, 75) )
  </code></pre>
  
  <p>If you view this in some image editing software like GIMP, it shows the Pixel per inch as 75, 75. </p>
  
  <p>But the above code doesn't work when the input image is a .bmp file. </p>
  
  <p>Could someone tell me how to change image resolution for any image  in python? </p>