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how to detect smile of a person ??

Asked by Sivakumaran Chandrasekaran on 22 Aug 2012

how to detect the smile of the person. whats the technology involved behind this??


Jan Simon on 22 Aug 2012

@Siva: We had a question here about the automatic detection of age, gender and race. The purpose of the program has been the display of customer specific commercials in a shopping mall. This sounds ok, but I'm will not longer be convinced about the ethical correctness, when the method is used to manipulate my less than 16 year old children to buy a certain sort of beer. And exactly this happens in Germany. Therefore I'm always careful with any kind of biometric recognition methods.

Walter Roberson on 22 Aug 2012

Siva, the discussion here references previous discussion; see

Thanks Walter.. I shall check it

Sivakumaran Chandrasekaran


2 Answers

Answer by Babak on 22 Aug 2012
Accepted answer

First you got to detect the line between the lips. After that you need to compute the arc angle of that line if it is caved towards up or down making the person look sad or happy. To detect a line in an image you can see the DEMO that involves finding the lines of the street's cars' lanes.

1 Comment

Thanks Babak. You gave a clear cut idea.

Answer by Image Analyst on 22 Aug 2012

Since these are patented methods, they will be explained in the patents. That's the agreement in a patent: you get exclusive right to use it for 20 years, but the public gets to know how it's done (no secrets anymore). Have you searched the patent database:

For just one example, US Patent 8170298: Method for detecting facial expression and repairing smile face of portrait photo

It's probably already in digital cameras. If not yet, then it will be soon.


Thanks Image Analyst

Walter Roberson on 22 Aug 2012

It is in the Nikon Coolpix series of cameras for the last 2 or so years. (I have one that has the feature.)

Image Analyst

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