[Plugin: NextGEN Gallery] NextGEN Thumbnails Question

I was wondering if there was a way to edit thumbnails so that when the thumbnails are displayed in the gallery parts of the image may be obscured, but when the thumbnail is clicked on and the full image is displayed the image is in its original form.

My question stems from my site, wwww.thelastbraincell.com, and sometimes I need to hide boobs and such from the front page. What I do now is create two seperate galleries. One for the images that are free of nudity, and one for the images that contain the boobies. The nude galleries are places on their own page protected by a password. So, if I was able to edit the thumbnails and hide the boobs and such from plain view I could post both the nude and non-nude galleries within the post on the front page instead of having to seperate them and requiring people to register for a password to the nude galleries page.

Thanks.