Detect Disguises with a Raspberry Pi


Computer vision based face detection systems are getting better every day. Authorities have been using face detection and criminal databases for several years now. But what if a person being detected is wearing a mask? High quality masks have been making their way out of Hollywood and into the mainstream. It isn’t too far-fetched to expect someone to try to avoid detection using such a mask. To combat this, [Neil] has created a system which detects face masks.

The idea is actually rather simple. The human face has a well-defined heat signature. A mask will not have the same signature. Even when worn for hours, a mask still won’t mimic the infrared signature of the human face. The best tool for this sort of job would be a high resolution thermal imaging camera. These cameras are still relatively expensive, so [Neil] used a Melexis MLX90620 64×8 16×4 array sensor. The Melexis sensor is interfaced to an Arduino nano which then connects to a Raspberry Pi via serial.

The Raspberry Pi uses a Pi camera to acquire an image. OpenCV’s face detection is then used to search for faces. If a face is detected, the data from the Melexis sensor is then brought into play. In [Neil's] proof of concept system, a temperature variance over ambient is all that is needed to detect a real face vs a fake one. As can be seen in the video after the break, the system works rather well. Considering the current climate of government surveillance, we’re both excited and a bit apprehensive to see where this technology will see real world use.


  1. Truth says:

    MLX90620 is 16×4. Where did you get 64×8 I can’t see that he is using 8 sensors which would explain your 64×8 ? It is late where I am may I’m missing something.

    • Adam Fabio says:

      You’re right, it 16×4 – I did catch and correct this this while writing, so I’m going go to with wordpress’ editor being out of sync. I should have given it one last check though.
      Either way – I’ve corrected it in the live article.

    • You still can’t see through the mask to determine the facial identity of the wearer. So it’s not as helpful as it could be if it were, say, backscatter microwave scanning everyone.

  2. ChopSueyAR says:

    So as long as it doesn’t detect a face, you’re good…

  3. Whatnot says:

    So he’s an amateur wannabe asshole government surveillance state bastard? To each his own I guess..

  4. truthspew says:

    If only – my RasPi is a piece of crap. The OS – it can hardly deal with my external WiFi adapter.

  5. Chuckt says:

    They will just have to enter masks in the criminal database.

  6. John Yossarian says:

    So just modify the masks to emit heat… not like all CCTV is running thermal imaging as it is very expensive.

  7. nomnoms says:

    so what happens to all the ladies wearing ten lbs of makeup?

  8. Erin says:

    It would be interesting to try to combat this. Thermographs don’t directly read temperature–they read emissivity in a certain band of IR light. I wonder if there are materials suitable to build up the IR profile that wouldn’t make the mask look weird in the visual spectrum.

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