cnn_filters.py

# https://github.com/ageron/handson-ml2/blob/master/14_deep_computer_vision_with_cnns.ipynb

import sys
assert sys.version_info >= (3, 5)

# Scikit-Learn ≥0.20 is required
import sklearn
assert sklearn.__version__ >= "0.20"

# TensorFlow ≥2.0-preview is required
import tensorflow as tf
from tensorflow import keras
assert tf.__version__ >= "2.0"

# Common imports
import numpy as np
import os
import matplotlib.pyplot as plt

figdir = "../figures"
def save_fig(fname):
    if figdir: plt.savefig(os.path.join(figdir, fname))
    
# to make this notebook's output stable across runs
np.random.seed(42)
tf.random.set_seed(42)

def plot_image(image):
    plt.imshow(image, cmap="gray", interpolation="nearest")
    plt.axis("off")

def plot_color_image(image):
    plt.imshow(image, interpolation="nearest")
    plt.axis("off")
    
import numpy as np
from sklearn.datasets import load_sample_image

# Load sample images
china = load_sample_image("china.jpg") / 255
flower = load_sample_image("flower.jpg") / 255
images = np.array([china, flower])
batch_size, height, width, channels = images.shape

# Create 2 filters
filters = np.zeros(shape=(7, 7, channels, 2), dtype=np.float32)
filters[:, 3, :, 0] = 1  # vertical line
filters[3, :, :, 1] = 1  # horizontal line

outputs = tf.nn.conv2d(images, filters, strides=1, padding="SAME")

plt.imshow(outputs[0, :, :, 1], cmap="gray") # plot 1st image's 2nd feature map
plt.axis("off") # Not shown in the book
plt.show()

for image_index in (0, 1):
    for feature_map_index in (0, 1):
        plt.subplot(2, 2, image_index * 2 + feature_map_index + 1)
        plot_image(outputs[image_index, :, :, feature_map_index])

plt.show()

def crop(images):
    return images[150:220, 130:250]

plot_image(crop(images[0, :, :, 0]))
save_fig("china_original", tight_layout=False)
plt.show()

for feature_map_index, filename in enumerate(["china_vertical", "china_horizontal"]):
    plot_image(crop(outputs[0, :, :, feature_map_index]))
    save_fig(filename)
    plt.show()

plot_image(filters[:, :, 0, 0])
plt.show()
plot_image(filters[:, :, 0, 1])
plt.show()