title: Get unique ID for pictures using Exif metada
body: <p>I've made a file crawler using python to read all my pictures in my computer (around 250 K files) and saving this information on a MySQL Database. I also save all the EXIF metadata for each file. 
  Next, I'll like to add tags to them associating them to an unique ID but that is always the same for the same picture, just in case I run my crawler again and the file changes it's location or it's name.
  For that purpuse I created a hash using string with relevant Exif information.</p>
  
  <p>I've taken into consideration that over the years I've taken pictures with different camaras or phones, and some Exif tags are not present in all cameras. I've also have seen that most tags don't have many different values that can make the string unique.</p>
  
  <p>Im using: </p>
  
  <p>Exif_Image_Length * Exif_Image_Width   (area of the picture)
  + Image_DateTime +   Image_Make + Image_Model</p>
  
  <p>and making a hash out of that string. I still get duplicates hashes instead of unique hashes.</p>
  
  <p>I'll love if someone has a better approach for what I'm trying to do.</p>
  
  <p>Thanks in advance,</p>
  
  <p>Pablo</p>
  
  <p>EDIT: I need to get an unique ID for images that every time I proccess that filename / exif metadata I get the same ID considering the filename and location might change (but EXIF data will remain intact)</p>