Does anyone have the code for Lee Sigma Filter in python?

I have been working on implementing Lee Sigma Filter for SAR images.I created a noisy image and filtered it using the code that i have written. But the SSIM value between the non-noisy image and the filtered image comes out too 0.45 only. Can someone help me identify the mistake in my code?

def std(image):

    np_img = np.array(image)
    d = np.std(np_img)
    return d
    
def sigma(image , k ):

    x_pixels,y_pixels=image.shape
    new_im = np.zeros((x_pixels,y_pixels), np.uint8)
    n_r = k // 2
    s = std(image)

    for x in range(x_pixels):
        for y in range(y_pixels):

            total = 0
            t = 0
            m=0
            M=0
            int_max = image[x,y] + (2 * s)
            int_min = image[x,y] - (2 * s)

            for x_i in range(max(0,x -n_r),min(x_pixels-1 , x +n_r) + 1):
                for y_i in range(max(0,y -n_r),min(y_pixels-1 , y +n_r) + 1):
                    
                    t += image[x_i,y_i]
                    m+=1
                    if (image[x_i,y_i] >= int_min and image[x_i,y_i] <= int_max):
                            total += image[x_i,y_i]
                            M = M + 1 
                total-=image[x,y]
                M-=1
                t -= image[x,y]
                m-=1
                if M >= 3  :
                            new_im[x, y] = total / M
                else :
                    new_im[x, y] = t / m
    return new_im