title: Get image file size from height and width values
body: <p>According to this answer <a href="https://stackoverflow.com/questions/477572/strange-out-of-memory-issue-while-loading-an-image-to-a-bitmap-object/823966#823966">here</a>, it is possible to read an image <code>height</code> and <code>width</code> without loading the whole image into memory.</p>
  
  <p>There is a sentence bit further down in the answer telling that</p>
  
  <blockquote>
    <p>bitmap of approximately 512x384. Loading this into memory uses 0.75MB
    rather than 12MB for the full image (assuming a bitmap configuration
    of ARGB_8888).</p>
  </blockquote>
  
  <p>My question is how you can calculate the <strong>image file size (or maybe I must say memory usage)</strong> of the image using the <code>height</code> and <code>width</code> like in the answer above. Also, what is this <code>ARGB_8888</code> value or how to get it?</p>