How to detect sunglasses in a human/facial region?

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Hi guys,

I am working on a project to detect human and check whether he/she is wearing a protection goggle(I simply assume its a sunglasses-like object)

This is what I did:

Trained my own classifier with linear SVM and HOG features,the data set came from Dalal's paper's resource plus my own images. Its performance is acceptable but not that good. (a very high FP rate when detecting). It worked fine in a given background..

Then I tried to detect the goggle in the human body region. I took 50 more pictures and saved the [forehead+sunglasses+noses] regions and trained them with linear SVM and HOG (2x2 pixels each cell and 2x2 cells each block) then almost every thing can be detected on the body excepted for the real sunglasses region....I am wondering if there is a good way to conduct the sunglasses detection? I am in hurry and have not time to try each features one by one....

(My training set is like this )

Sorry for my english and a great many thanks guys!

Nick