In contact I have member photos(JPEG files). I am creating a UI to display (using Apex and visualforce) all the attachments with a check box by it's side. The User will have the ability to choose the files they like to download and click a download button all the slected records should get  downloaded without viewing the record. how can i acheive this? I tried using java script i n the code its not working. \

Note:The files are getting downloaded automatically it the file is a word document or a XLS document. If the document is a Image file how we can do this?