What if- Compulsory photo categorization on Internet

These days you can hardly spend two hours with friends without discussing something on Facebook. A couple of my friends shared about their friends who posted graphic images of people eating dogs and broken heads on the Facebook. They complained that these images spoilt their mood. What if it was made compulsory for all websites that before uploading any image the user has to specify whether it contains any nude and graphic content or not. This should be enforced on all websites through the Internet regulatory bodies. And the web browser should be able to block the images with nude and graphic content which will only show upon clicking.