The add-on "Save Images "at https://addons.mozilla.org/fr/firefox/addon/3404 does not actually deliver 100% what it promises. It starts downloading the images when asked to save. It should actually NOT be installed since it doesn't provide you with an option to redownload if the download stops sometimes for any reason. In case of direct download, at least you get a list of files downloaded or that failed to download so you can go to the download page again. (And, though not everyone may agree, it's a matter of ethics to not use an application that says something else and does something else.) I strongly hate this add-on now.
THE ADD-ON SAVE IMAGE AT https://addons.mozilla.org/fr/firefox/addon/3404 SHOULD NOT BE USED; IT TELLS YOU THAT IT SAVES IMAGES FROM CACHE WHICH IS ABSOLUTELY FALSE. IT DOWNLOADS THE IMAGES AGAIN WHEN YOU SAVE THE IMAGES THROUGH IT.
The other software at http://www.nirsoft.net/utils/m.....iewer.html does exactly what it promises and is quite good. But there's an inherent limitation to it: Since Firefox saves its cache data only when it exits, the mentioned program doesn't have access to the cache of the files currently being created by FF. In other words, when I open a web page and load it fully with its images, the cached data cannot be accessed just yet by the program MozillaCacheView, and hence I'm again unable to save it directly from cache. (I'll have to close FF every time I want to save a new image. You can imagine it's worse than downloading it again.)
Besides, not all the images displayed on the page are being cached and can be found in the cache after closing the browser; some are just loaded into RAM that vanish as soon as we close all the pages using them or when we exit the browser. There's no way to tell the browser which images to save in the cache and which to load into the RAM.
1-10.