Gaussian Blur (filter) example from scracth

gaussian-borroso.py

import numpy as np
import matplotlib.pyplot as plt
from scipy.signal import convolve2d


def build_filter(size, sigma):
    # Construir matriz gaussiana 3x3
    x = np.arange(-size / 2 + 1, size / 2 + 1)
    y = x[:, np.newaxis]

    x0 = y0 = size // 2
    gauss = (
        (1 / (2 * np.pi * sigma**2))
        * np.exp(-((x - x0) ** 2 + (y - y0) ** 2) / (2 * sigma ** 2))
    )

    # gauss /= np.sum(gauss)
    return gauss


def build_image(size):
    size = size
    image = np.ones((size, size))  # 1 is Black
    # Find center and paint around it
    center = size // 2
    white = 0
    image[center, center] = white
    image[center - 1, center - 1] = white
    image[center + 1, center + 1] = white
    image[center - 1, center] = white
    image[center + 1, center] = white
    image[center, center - 1] = white
    image[center, center + 1] = white
    return image


def plot(image, image_blur):
    _, (ax1, ax2) = plt.subplots(1, 2)
    ax1.imshow(image, cmap='gray')
    ax2.imshow(image_blur, cmap='gray')
    plt.show()


size = 3
sigma = 5
im_size = 10

gauss = build_filter(size, sigma)
image = build_image(im_size)

print(f"filter: \n{gauss}")
print(f"image: \n{image}")

image_blur = convolve2d(image, gauss, mode='same')

plot(image, image_blur)