Strip exif data from images
You can do this by implementing hook_file_presave($file)


  This hook is called when a file has been added to the database. The hook doesn't distinguish between files created as a result of a copy or those created by an upload.


In this hook, you need to:


Test if file is really an image. I suggest using mimetype for this task: $file-&gt;filemime
Recognize which image processing library your Drupal is using. See image_get_available_toolkits(), image_gd_check_settings() and ImageMagick.
Process that file. This part is general programming issue already well answered on Stack Overflow - I see no point in reposting it here, I think I covered Drupal part of the question now.