Make sure users aren't asked to save for every image (may be settings-dependent)

[kevinsqi]

trafficstars

[blurymind]

https://developer.chrome.com/extensions/downloads#method-download

Suggestion: prompt the user where to save the first image, then use that path in order to save the rest

There are sone addons already that can pop out programatically a save as dialog

[blurymind]

http://stackoverflow.com/questions/20988041/how-to-set-the-file-download-location-for-chrome-extension-using-javascript

[blurymind]

Will that help you implement it now? :)