in my site i have pagespeed-corefilters enabled, however, when i execute some JQuery script that add a background image to a div, this image is not cached.
It seems that pagespeed can't see these images. In fact the response headers of all these images are not signed by x-page-speed
The problem occurs in this page https://mtgfiddle.me/deck
Is there any possibility to cache these images?
No, mod_pagespeed cannot cache extend resources added by JavaScript. However, it can still optimize them using InPlaceResourceOptimization: https://developers.google.com/speed/pagespeed/module/system#ipro