Function to fix a problem with Photon (Jetpack module from WordPress/Automattic) ignoring image crops that are made through the CMS (with plugins like https://wordpress.org/plugins/manual-image-crop/).

get_image_url.php

/**
 * Get URL of an Editor cropped (manual or automatic) version of an image (and get Photon URL if wanted)
 * https://gist.github.com/dominicfallows/457334ef84e3a805f7201fd8762ce569
 *
 * @param integer $imgID The attachment media ID
 * @param string $size (optional) The registered image size you want. Default 'full'
 * @param bool $photon_if_available (optional) If Photon is available, return the Photon-ized URL Default true
 * @return string
 */
 
function get_image_url($imgID, $size = 'full', $photon_if_available = true) {
  
  // Is Photon available and not in development mode
  $photon_if_available = class_exists('Jetpack') && method_exists('Jetpack', 'get_active_modules') && in_array('photon', Jetpack::get_active_modules()) && !Jetpack::is_development_mode();
      
  // If Jetpack is installed, Photon is active and we're not in development mode - then disable Photon
  if($photon_if_available) {
    $photon_removed = remove_filter( 'image_downsize', array( Jetpack_Photon::instance(), 'filter_image_downsize' ) );
  }  
  
  // Get the local URL of the Editor cropped (manual or automatic) version of the image
  $local_img_src = wp_get_attachment_image_src ($imgID, $size);
  
  // If we've previously disabled Photon, renable it
  if($photon_removed) {
    add_filter( 'image_downsize', array( Jetpack_Photon::instance(), 'filter_image_downsize' ), 10, 3 );
  }
  
  // If we want to, now Photon-ize the image, otherwise keep the local url
  $img_url = $photon_if_available ? jetpack_photon_url($local_img_src[0]) : $local_img_src[0];
  
  return $img_url; 
  
}

Add this function to your themes function.php or your plugin includes to use it in place of other image retrieval functions