In its recent search engine updates, Google has modified its search algorithm that makes hard to find p0rnographic content on the web. Google clarifies that it has not censored any p0rn material but unless a user specifically asks for p0rn, p0rn links will not be shown in the results even with SafeSearch off. This will be applicable to Image Search as well as Web Search.
About the update, a Google representative said :
We are not censoring any adult content, and want to show users exactly what they are looking for—but we aim not to show sexually-explicit results unless a user is specifically searching for them. We use algorithms to select the most relevant results for a given query. If you’re looking for adult content, you can find it without having to change the default setting — you just may need to be more explicit in your query if your search terms are potentially ambiguous. The image search settings now work the same way as in Web search.
It appears that Google is concentrating on delivering more answer centric results i.e. to answer a specific query. Knowledge Graph was successfully implemented this year on May 16, 2012 to fetch more valuable encyclopedic data about specific queries, with first trials in USA.
The updates are however now only applicable for Google users in USA, but Google is planning to implement it soon to more languages and regions, after there is favorable trial in USA.