That’s a good question! I work on the Jetpack team, but I’m not familiar enough with how LiteSpeed Cache works to give you the perfect answer. I can, however, tell you how Jetpack’s Photon works, so the folks from the LiteSpeed Cache team can then jump in ??
Photon does not make any changes to the images in your media library, or to the image links you add to your posts in the post editor. That part won’t change. What we do change is the path of the images on the front end of your site. For example https://jeremy.hu/wp-content/uploads/loxv7Howo5NoD5r5fXwlDT2HqLr-700x240.jpg becomes https://i1.wp.com/jeremy.hu/wp-content/uploads/loxv7Howo5NoD5r5fXwlDT2HqLr.jpg?resize=700%2C240
Behind the scenes, when that i1.wp.com is loaded by a reader on your site, the Photon bot visits your site, downloads the original image (https://jeremy.hu/wp-content/uploads/loxv7Howo5NoD5r5fXwlDT2HqLr.jpg in this case), resizes that image to match the requirements, optimizes it with a lossless image compression algorithm, creates a WebP version of the image, caches the end-result, and serves it to the reader on the site.
Once that’s all done, we do not fetch the original image again. We rely on the cached image we have instead.
I’m not entirely sure how LiteSpeed Cache’s image optimization works, but it seems it is something that does not happen on image upload by default. Instead, it is something you can trigger with a button in the dashboard. That also means that by the time you click on that button, the image may have already been cached by Photon. The changes made by LiteSpeed Cache would consequently not be visible on the site. They would not hurt either; nothing would break. But it may not be that useful to use the 2 features together.
I’ll let the LiteSpeed Cache team jump in and confirm that it is indeed how the plugin works ??
