Like Paul said, it depends. HOG is not invariant to in-plane rotation, which may be ok if you are trying to detect pedestrians, which are typically not upside down. On the other hand, if you are trying to recognize objects form aerial images, invariance to rotation may be crucial. SIFT and SURF are invariant to rotation. SIFT can be a bit more accurate, but SURF is much faster.
Sheema it histogram can be used for extracting features. I am using histogram of a color image for extracting features in face segmentation. But in case of color images rgb image is first converted into hsv and then features are extracted. While extracting then features you have to use number of bins you needed which then depends on the size of the image and type.
I HAVE USED KMEAN AND FCM FOR SEGMENTATION AND NOW M SUPPOSE TO CLASSIFY NORMAL AND ABNORMAL BRAIN MRI AND IF IT IS ABNORMAL THEN BEGNIN OR MEGNIN..ANY SUGGESTION HOW TO PROCEED??