turn on the google version of "child safe" in your google browser options - called safe search
" child safe", like all other non-core virgin products is a POS. ( deliberate language choice)- though to be charitable, child safe is a program that checks for dodgy web site addresses , then blocks either everything or nothing. and do you really want it to block all of google ?
it is not easy to write code that detects sexuality in images, even facebook has had some well publicised recent fails at that.
google definitely has an image censor built in, google " google safe search"
and for better filtering generally you can change your PC to use open DNS instead of virgin defaults, and then use a free open DNS account to set exactly what you want blocked.