A biometric is A measurable physical characteristic or personal behavioural trait used to recognise the identity of an enrollee or verify a claimed identity.

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• Bio -> life -> (LIVING) individual or group Metric -> measure -> comparable for establishing identity of "biometric" refers to a characteristic that satisfies the TWO.
• Face is then a biometric. Scars or tattoos can be if they are able to do the above. The same biometric can be in many forms - photographs, digital images.
• It can also be transformed from raw -> features -> templates.
• Provided the photograph has been captured in line with ISO 19794-5 then it is "a measurable physical characteristic" of a person, ergo it is.
• But if it is a photograph of a house, a silhouette of a person, a photograph of multiple people - then it would not pass the ISO 19794-5 tests, so it would not be.
• Given that ISO-compliant hardcopy photos (and sometimes ones that aren't) can be scanned and uploaded to generate templates that work with facial matching systems, you'd have to say in that sense a photograph also is a biometric.
• By our ISO 19794-5 definition, for the photo to be a biometric, there is an intent that the photo is captured for biometric matching PURPOSES and QA checked against standards as part of that process, against a neutral background. So we'd argue that a passport style photo of a person taken at random at home would not be a biometric because it was not taken for biometric measurement purposes.
• A biometric is any biological attribute that can be used for identification - hence strictly a photo qualifies, as does in fact a picture or video of any part of the body. However just because a selection of photos exists of employees for instance (ICAO compliant or not) this does not mean there is the capability or intention to do anything biometric with the photos. 
• In other words they could be called 'latent' biometrics - similar to a latent fingerprint that is left on a surface but that MAY not be used. Any clear photo of a person contains some biometric information - but if there is no intention to convert it to a template or match it against a facial gallery then I would say it is open to debate as to its status as a biometric in the technical or legal sense.
• It's the purpose that counts. A driver licence authority that has photos stored for the purpose of identification (biometric) might be different from a human resources use or facebook style application ('latent' biometrics). For instance consider video LIBRARIES and TV stations or newspapers, they might be considered vast biometric repositories if any photo of a human qualified as a biometric. Obviously purpose can change - and so what was a 'latent' biometric might become an actual biometric with a change of usage.

A biometric is A measurable physical characteristic or personal behavioural trait used to recognise the identity of an enrollee or verify a claimed identity.

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