Make sure your ad will pass our flashing testing
There are strict rules about the use of flashing images and regular patterns in adverts. This is to reduce the risk of exposing TV viewers that suffer from photosensitive epilepsy to potentially harmful stimuli.
Ofcom has produced guidelines on Flashing Images, see Annex 1 of the document below.
Ofcom Guidance on Harm and Offence
When you submit an ad to us, we automatically run it through a system that tests for this issue as part of the clearance process. The test is commonly known as the Harding test after the inventor of the system.
If your edit fails our flashing test, you have two options:
- You can use our Online Flash Test service to see where in the ad the fail has occurred, amend the edit and re-submit with a new clock number. We can help you make these amends as part of our edit-to-clear service
- Alternatively we will accept a certificate from any device on the DPP (Digital Production Partnership) list that indicates the clocked ad has passed an accepted flashing test (new from October 2018). Note that certain criteria, minimum product and algorithm versions must be observed see Checklist.
The certificate generated by the system must display the information below. Amended certificates will not be accepted..
- Ad Title Field — this must include the ad’s full clock number.
- Duration of material tested — the exact duration of the file tested including any pre and post-roll.
- Video standard — this must be at least Standard Definition and one of the following values:
- Frame Rate - this must be either: 25 frames (if interlaced) or 50 frames (if progressive).
See the full Checklist PDF document: Checklist.
For further details about the Harding certificate, or general questions about testing your ad for flashing images and regular patterns, get in touch with either your Clearcast contact or the Operations team via 020 7339 4780. You can also visit our help desk.
- See our legal supers test card
- What is a clock number?
- Use our duration of hold calculator
- Use our online flash test