It’s not news that it is possible to use a laptop computer (or other device)’s built in camera to take pictures without the current user being aware of it. I ran across some discussion of this recently which seemed odd. Some people suggest (e.g. here) that the standard security response of taping (or equivalent) over the camera is inadequate because a usable image might still be obtainable by post-processing. The suggestion may not be serious, but it hadn’t occurred to me; I have never thought much about whether a piece of metal foil tape or black tape would be better than the little square cut out of a post-it note I’ve been using all these years. I prefer a post-it note because it’s easy to remove if you ever actually want to use the camera — though there’s nothing stopping you using metal foil tape on top of a post-it note.

Anyhow, evidence. This is a self-portrait image taken with my laptop webcam, with a light shining directly on me, through a single layer of purple post-it note. The original image was almost black, so I ran it through the Photoshop Equalise filter.

The speckling is partly jpeg and partly low-light randomness. However, I suspect it would be a challenge to extract a usable image from this even if you could access the raw data. It doesn’t even give much opportunity for pareidolia. Semitransparent tapes might not give the same level of protection.

Result: Probably not a security issue in the foreseeable future. And I’m quite pleased with this picture. I look much prettier than usual.  

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