Source file: class.photon.phpView in GitHub
(bool) Should Photon ignore images using the HTTPS scheme. Default to false.
Since: Jetpack 2.4.0
By default, Jetpack’s Photon service will fetch and serve all images on your site, whether you use HTTP or HTTPS. You consequently do not need to use this filter to be able to use Photon on a site using HTTPS.
However, in some situations you may not want Jetpack to serve your HTTPS images. In such edge-cases, you can use this filter like so:
add_filter( 'jetpack_photon_reject_https', '__return_true' );