Flashing checklist

Flashing checklist

Make sure your ad will pass our flashing testing

There are strict rules about the use of flashing images and regular patterns in adverts 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 our internal test system as part of the clearance process.

If your edit fails our flashing test, two options are available:

  • 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 you can provide us with a ‘Harding certificate’ that indicates the edit has passed a flashing test. The certificate must display the information below.

  • Ad title — this must include the ad’s full clock number.
  • Duration of material — this is the length of the ad.
  • Video standard — must be one of the following values:
    • 576i50
    • 576p25
    • 1080i50
    • 1080p50

  • Material status — this must be one of the following values:
    • PASSED
    • PASSED (with caution)

  • Testing algorithm used — must be v3.4.0 or more recent
    • This is the version of the HFPA-X analysis software that the ad has been tested with.

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 Mark or Greg in the Operations team via 020 7339 4700. .

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