I want to quantize HOG features of an image into 4-5 salient regions. How can I do so?

I have got the HOG features of an image using extractHOGFeatures function of matlab. But then I need to quantize them into salient regions to perform k means clustering on them. I got stuck at the quantization part.

[Dima Lisin]

Not sure, what you mean. Typically, a HOG feature vector describes the entire image.