The dark region to the right has some strange looking things in it but is not the original "Face" feature.
The region in the rectangular outline is the reason that artificiality is suggested.
The hypothesis was that the feature under consideration from the Viking images of 20 + years ago is artificial. If someone were to test this hypothesis they might say get me a closer image realizing that this would cut down the field. If they were given a closer image that only contained what looked like the "eyebrow" region on the Viking images (there are at least 8 Viking images of this feature)a prediction might be, if the feature was artificial a closer better resolution image might give an artistic impression of individual eyebrow hairs if the feature was natural the law of increasing entropy would make any "dunes"
disperse and look less like an "eyebrow".
The result was that the "dunes" didn't randomly disperse after 24 years in the Martian wind, but rather upon closer inspection the feature looked even more like an "eyebrow" with individual eyebrow hairs being visible.
Theories have been suggested that the structure was "drawn" by a particle beam from above (the "face" is aproximately 6 miles by 6 miles) melting sand to a dark glassy material. The region to the right could have been "doodles" as the aerial artist tested his euiptment.