utils.py

# Most code in this file was borrowed from https://github.com/Hvass-Labs/TensorFlow-Tutorials/blob/master/15_Style_Transfer.ipynb

import matplotlib.pyplot as plt
import numpy as np
import PIL.Image

"""Helper-functions for image manipulation"""
# This function loads an image and returns it as a numpy array of floating-points.
# The image can be automatically resized so the largest of the height or width equals max_size.
# or resized to the given shape
def load_image(filename, shape=None, max_size=None):
    image = PIL.Image.open(filename)

    if max_size is not None:
        # Calculate the appropriate rescale-factor for
        # ensuring a max height and width, while keeping
        # the proportion between them.
        factor = float(max_size) / np.max(image.size)

        # Scale the image's height and width.
        size = np.array(image.size) * factor

        # The size is now floating-point because it was scaled.
        # But PIL requires the size to be integers.
        size = size.astype(int)

        # Resize the image.
        image = image.resize(size, PIL.Image.LANCZOS) # PIL.Image.LANCZOS is one of resampling filter

    if shape is not None:
        image = image.resize(shape, PIL.Image.LANCZOS) # PIL.Image.LANCZOS is one of resampling filter

    # Convert to numpy floating-point array.
    return np.float32(image)

# Save an image as a jpeg-file.
# The image is given as a numpy array with pixel-values between 0 and 255.
def save_image(image, filename):
    # Ensure the pixel-values are between 0 and 255.
    image = np.clip(image, 0.0, 255.0)

    # Convert to bytes.
    image = image.astype(np.uint8)

    # Write the image-file in jpeg-format.
    with open(filename, 'wb') as file:
        PIL.Image.fromarray(image).save(file, 'jpeg')

# This function plots the content-, mixed- and style-images.
def plot_images(content_image, style_image, mixed_image):
    # Create figure with sub-plots.
    fig, axes = plt.subplots(1, 3, figsize=(10, 10))

    # Adjust vertical spacing.
    fig.subplots_adjust(hspace=0.1, wspace=0.1)

    # Plot the content-image.
    # Note that the pixel-values are normalized to
    # the [0.0, 1.0] range by dividing with 255.
    ax = axes.flat[0]
    ax.imshow(content_image / 255.0, interpolation='sinc')
    ax.set_xlabel("Content")

    # Plot the mixed-image.
    ax = axes.flat[1]
    ax.imshow(mixed_image / 255.0, interpolation='sinc')
    ax.set_xlabel("Output")

    # Plot the style-image
    ax = axes.flat[2]
    ax.imshow(style_image / 255.0, interpolation='sinc')
    ax.set_xlabel("Style")

    # Remove ticks from all the plots.
    for ax in axes.flat:
        ax.set_xticks([])
        ax.set_yticks([])

    # Ensure the plot is shown correctly with multiple plots
    # in a single Notebook cell.
    plt.show()