You could use the context menu with
;c and choose the 'save as'-option. Alternatively open the image in a new tab with
;I and save it with
ctrl+s, but it's slow when wanting to save a lot of images.
This is a somewhat "hidden" feature in Vimperator:
For some reason it's not listed in the online version of Vimperator's Hint documentation, only on the one included in the addon (using