`shape` and `sigma` not defined.

[suvojit-0x55aa]

https://github.com/jiawenzhou0627/image-quality-assessment-python/blob/eabea767542e873fd1543f9622dc29e67bd91972/brisque_features.py#L10

I'm getting the following error for this.
NameError: global name 'shape' is not defined

https://github.com/jiawenzhou0627/image-quality-assessment-python/blob/eabea767542e873fd1543f9622dc29e67bd91972/brisque_features.py#L12

And here for sigma.

[guptapraful]

replace this
def get_gaussian_filter():
with
def get_gaussian_filter(shape = 7, sigma = 7/6.0):

to reproduce results of the paper