title: How to determine coordinate of grid elements of an image
body: <p>Given an image of with a known dimension (eg. 14782 x5495 pixels) and a desired square size (e.g. width,height = 696 pixels) size, how can I get the coordinates of each element in the grid?</p>
  
  <p><a href="https://i.stack.imgur.com/vdF8J.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vdF8J.jpg" alt="enter image description here"></a></p>
  
  <p>In actuality, my image has no grid. But I'd like to get the coordinate as if the grid exist as shown above.</p>
  
  <p>The coordinate is define as follows:</p>
  
  <blockquote>
    <p>The x and y are the coordinates (in pixels) of the upper left corner
    of the selection. The origin (0,0) of the coordinate system is the
    upper left corner of the image.</p>
  </blockquote>
  
  <p>The core majority of the grid element size is fixed for all given input image. (e.g. square with size width x height = 1000x1000 pixels). The shape of the surrounding elements of the grid is not squared, that's ok.</p>
  
  <p>So exactly like the grid scheme as shown in the image above.</p>
  
  <p>The actual image is <a href="https://dl.dropboxusercontent.com/u/16295340/04_709_channel-3.tif.zip" rel="nofollow noreferrer">downloadable here</a> (160MB).</p>