title: Resize image to specific width and fix height
body: <p>I want to resize big images to have a width of 150 pixels and the height will be fixed.
  and then save the image into a folder in my website.</p>
  
  <p>examples: (width,height)
  if I resize an image 300px*300px I will get a resized image of 150px*150px.
  if I resize an image 450px*300px I will get a resized image of 150px*100px.</p>
  
  <p>the point is that the ratio between width and height will be saved always keeping a width of 150 pixels.</p>
  
  <p>Any Help?</p>