As the UK government pushes ahead with plans to crack down on pornography, Twitter is reportedly set to join Facebook in implementing a tagging system to prevent indecent images from being posted to the service. According to The Guardian, Twitter will introduce Microsoft's PhotoDNA technology to process and filter images uploaded to its platform by the end of the year, but will come independently of UK policies. The software uses a mathematical hash to match images against a list of known pictures, recognizing offending images even if they have been altered.

PhotoDNA was developed in conjunction with the National Center for Missing and Exploited Children and has already become an industry standard for monitoring images online. Facebook licensed it in 2011, becoming the first service to use the technology, while authorities also use it to conduct reverse image searches and filter copyrighted content. In a bid to limit the influence of pornography on children, the UK government will introduce new measures requiring UK residents to declare whether they want access to adult content in their home, also outlawing the possession of violent pornography and illegal image searches.