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Haar Cascades: Limiting detectMultiScale to just one set of facial features?

asked 2018-12-29 19:25:06 -0500

byoon gravatar image

I am currently running OpenCV version 3.4.4 on Python 3.7.1 and designed a program that utilizes the eye haar cascade classifiers. The program runs fine but often misinterprets the center lower lip or one of the nostrils as a false eye. Is this a problem with the cascade I am using? Are there ways to limit my program to only the two most prominent eye features?

Here is an example: image description

While on the subject of Haar Cascades, when using the detectMultiScale function to find the position of the face, I noticed that when the face is moved upwards, the y-value actually decreases. Why might that be the case?

Any and all help is appreciated, B

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answered 2018-12-29 22:29:50 -0500

berak gravatar image

updated 2018-12-29 23:16:24 -0500

misinterprets the center lower lip or one of the nostrils as a false eye.

indeed, the eye / mouth cascades are quite inaccurate. there are better alternatives, like facial landmarks (e.g. from dlib, flandmark, openpose. opencv also has pretrained landmarks models, however, they're not usable from python, currently)

when the face is moved upwards, the y-value actually decreases

the image origin (0,0) is top-left, and the y axis is pointing down

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Asked: 2018-12-29 19:25:06 -0500

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Last updated: Dec 29 '18