Now I am working on NCR. I have used hog,phog,co-occurence hog for natural character recognition. Even i have tried deep learning with RBM. But I got 50% accuracy only so please suggest me a best feature extraction method.
In the attached paper a feature called Oriented Basic image Feature is compared with other features ( SIFT, ABBYY, Shape Context, HOG...). It may help you.
Conference Paper Natural Image Character Recognition Using Oriented Basic Ima...
I think your approach of using HoG is very appropriate, because HoG has always proven to be the best for natural scenes. However, I think you should consider combining HoG with Bag-of-word Modelling and a dimension reduction approach. Please, have a look at this paper, where we used HoG in combination with PLSA, and achieved good accuracies.
The state of the art natural image recognition algorithms are generally a variant of Deep Convolutional Neural Networks (CNN). Recently, these algorithms win Large Scale Visual Recognition Challenge 2014. Some of the algorithms reported as surpasses human-level performance. I write a summary and review on the following link: