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Query in face detection apps

asked 2013-07-01 23:18:44 -0500

Hardik gravatar image

In face detection apps, why only face is detected? why hands or background is not detected? what is the logic that only face is detected?

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please clarify, if you're talking about detection ( are there faces, where, and how many ) or recognition ( who is it )

a cascade based detection will return several faces, while the recognition will return the closest match from the training set.

berak gravatar imageberak ( 2013-07-02 04:27:24 -0500 )edit

Hardik, haar-like features are commonly used for face (or object) detection, but they can be used for face (object) recognition also. Check this paper: (The proposed system in this paper introduces the novel idea of using Haar-like features, which have commonly been used for object detection, along with a probabilistic classifier for face recognition.)


So, face detection and recognition are two different things

albertofernandez gravatar imagealbertofernandez ( 2013-07-02 08:01:10 -0500 )edit

albertofernandez, did you find a free version of above paper ?

berak gravatar imageberak ( 2013-07-02 13:36:25 -0500 )edit

thanks a ton ;)

berak gravatar imageberak ( 2013-07-03 02:46:45 -0500 )edit

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answered 2013-07-02 01:36:14 -0500

A detector is built in order to recognize faces. To train the detector, a set of face and non-face training images are used. For example:

The face training set consisted of 4916 hand labeled faces scaled and aligned to a base resolution of 24 by 24 pixels. The non-face subwindows used to train the detector come from 9544 images which were manually inspected and found to not contain any faces [1].

So this detector is designed to only detect faces. But you can train the detector to detect eyes, mouth,....

[1] Viola, P., & Jones, M. (2001). Rapid object detection using a boosted cascade of simple features. In Computer Vision and Pattern Recognition, 2001. CVPR 2001. Proceedings of the 2001 IEEE Computer Society Conference on (Vol. 1, pp. I-511). IEEE.

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Thank you very much.

Hardik gravatar imageHardik ( 2013-07-02 02:10:24 -0500 )edit
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Asked: 2013-07-01 23:18:44 -0500

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Last updated: Jul 02 '13