I tried to Google-search the images on my site. Some of them appeared. But if I check the "Safe search" option there are no of them displayed. All images absolutely free of adult content or something like that. Text placed on the pages shouldn't scare Google as well. What should I do to prevent Google from filtering my images?
this http://www.webpronews.com/could-googles-safesearch-be-costing-you-traffic-by-filtering-your-safe-images-2013-10 may help you, but in general check the following:
check your text content and image filenames for things that Google could view as adult words
make sure your outbound links aren’t pointing to any adult areas
make sure you’re not hosted on the same server as an adult site.
If you have third party ads in your site, make sure they're not adult-related