Can anyone help me implement the iradon transform (back-projection) without filter??? I kinda know the concept but it's hard to implement it.

This is my code for radon transform (forward projection)

```
def sinogram(img):
radon = np.zeros((len(img), len(img)), dtype='float64')
for i in range(len(img)):
rot = misc.imrotate(img, -i * 180 / len(img)).astype('float64')
radon[:, i] = sum(rot) # Sum is the integral in Radon transform
return radon
```