This capability is called out as a specific Option, since it may be extremely burdensome in practice to implement and is unnecessary for the vast majority of anatomic sites and modalities.

In the case of full-face photographs, the risk of visual identification is obvious, and numerous techniques are well established for de-identification, such as applying black rectangles over the eyes, etc.

In the case of high-resolution cross-sectional imaging of the entire head and neck, it has been suggested that a 3D volume or surface rendering of the pixel data may be sufficient to allow identification (or matching against a constrained subset of individuals) under some circumstances.

Application of this Option may render the pixel data unusable for the purpose for which it has been collected, and hence its use may require a compromise between de-identification and utility based on obtaining appropriate ethical approval and informed consent. Consider for example, the case of dental images.

Since the Referenced Patient Photo Sequence is removed as part of the Basic Profile, support of the Clean Recognizable Visual Features Option does not add requirements for that Attribute.