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How to categorize the images based on Illumination / shadow ?

asked 2012-11-06 08:33:23 -0500

UserOpenCV gravatar image

My Question in short form: How to categorize the images based on Illumination / shadow ?

Input: Cropped face or Non Cropped face images.

Detailed explanation: My project is face authentication. I am using OpenCV face detector to crop face from images. I am using OpenCV implementation of LBP for face recognition. My face recognition system works good when the the test images are not much variant (illumination) w.r.t training images. The constraint is, I don't have many variants during training; so, I need to categorize the images based on light/shadow and need to label each image . So that similarity score threshold value can be set dynamically based on the labels. I am not getting the desired results with the Illumination normalization algorithms (like Difference of Gaussian) and with the static threshold values for all variants of images . So, I need to know how to identify the quality(illumination) of images, to check the possibility of dynamic thresholds.

Any guidance on any of my above said process are appreciated and helpful to me.

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answered 2012-11-06 14:14:11 -0500

alexcv gravatar image

updated 2012-11-07 07:48:38 -0500

Hi, Actually, measuring illumination amplitude may be not correlated to your application context. Indeed, your interest is related to facial features, luminance is only a distractor. So your features extraction should rather be robust against luminance rather than finding thresholds, etc to adapt to it in a risky way. In previous research, we used as a preprocessing tool the retina model recently proposed in OpenCV (check the contrib module). The aim was to limit the impact of lighting and enhance local face features. It can also enable face motion extraction. Have a look at it, it can improve your algorithm robustness and generalization potential.

Regards Some references : Benoit A., Caplier A., Durette B., Herault, J., "USING HUMAN VISUAL SYSTEM MODELING FOR BIO-INSPIRED LOW LEVEL IMAGE PROCESSING", Elsevier, Computer Vision and Image Understanding 114 (2010), pp. 758-773: http://dx.doi.org/10.1016/j.cviu.2010.01.011. Benoit A., Caplier A., "FUSING BIO-INSPIRED VISION DATA FOR SIMPLIFIED HIGH LEVEL SCENE INTERPRETATION: APPLICATION TO FACE MOTION ANALYSIS", Elsevier,Computer Vision and Image Understanding 114 (2010), pp. 774-789: http://dx.doi.org/10.1016/j.cviu.2010.01.010.

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Thanks for your reply.I ll have a look into it and get back to you if I have any queries. By the way the links you have provided are broken am getting some error message!! Can you please have a look into my other posts too? these are the links for my post. Hope you could suggest me some ideas on this too. http://answers.opencv.org/question/3777/face-detect-and-cropping/ http://answers.opencv.org/question/3776/red-eye-detection/

UserOpenCV gravatar imageUserOpenCV ( 2012-11-06 23:21:31 -0500 )edit

Hi, thank you for the remark, i updated doi links. it should work now. regards

alexcv gravatar imagealexcv ( 2012-11-07 07:49:43 -0500 )edit

Thanks a lot. Please have a look at my other posts too and pour your suggestions!! http://answers.opencv.org/question/3776/red-eye-detection/ http://answers.opencv.org/question/3777/face-detect-and-cropping/

UserOpenCV gravatar imageUserOpenCV ( 2012-11-07 08:27:03 -0500 )edit
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Asked: 2012-11-06 08:33:23 -0500

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Last updated: Nov 07 '12