Unique image analysis


As well as providing an analysis based upon ‘reports’ of child sexual abuse, where a report may contain one, or many tens, hundreds or even thousands of images, we can also provide an analysis based on individual images.

We use our bespoke grading and hashing software, called IntelliGrade, to enable us to perform an image-level assessment of images and videos, and to hash the image or video for sharing in our datasets to industry and law enforcement.

A hash is a type of digital fingerprint, or string value that identifies a picture of confirmed child sexual abuse.

Each hash is completely unique. Once an image has been hashed, it can be recognised quickly. This means thousands of criminal pictures can be blocked from ever being uploaded to the internet in the first place.

IWF began hashing child sexual abuse images in 2016.

By the end of 2023, we had accumulated 2,255,390 individual hashes of criminal images and videos.

In 2021 we launched our Taskforce, a team dedicated to hashing images, which was originally funded by Thorn and latterly the Home Office as part of our work with the Child Abuse Image Database. You can read more about this and our partnership with the UK Government’s Child Abuse Image Database here.

Total unique hashes by severity and age

This chart details unique hashes of child sexual abuse split by age and severity (category). The largest age category in both Categories A and B is where the youngest child in the image is estimated to be between 7-10 years old.

The total number of unique image and video hashes include 2,893 hashes of prohibited imagery which are not represented in the above severity chart.

In the UK, The Coroners and Justice Act 2009 criminalises the possession of “a prohibited image of a child”. These are non-photographic – generally cartoons, drawings, animations or similar. 

Total unique hashes by severity and sex

This chart shows the unique hashes of child sexual abuse split by severity (category) of abuse and sex of the child. Most of the hashed images across all severity categories depict girls. The ‘Unidentified’ bars are where it was not possible to identify whether the image or video was of a male or female child.

Analysis of IntelliGrade hashes; sexual activity metadata

This chart provides more detail on the exact nature of the abuse seen in an image which has been hashed by our analysts using our bespoke software, IntelliGrade.

Note: Some older hashes are not included in the above table of sexual activity metadata.