Making a gif from image files using PIL

.Making a gif from image files using PIL.md

Making a gif from image files using PIL

The pillow (fork of PIL, the Python Image Library) module presents a simple way to create a gif out of pre-existing image files, demonstrated below. More documentation can be found here. The intermediate image files which are generated by this Gist are not included directly, but can be generated by running the Python script.

make_gif.py

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

def make_gif(
    output_name,
    output_dir,
    input_path_list,
    duration=100,
    optimise=False,
):
    """ Make gif using pre-existing image files, and save to disk. The gif will
    loop indefinitely.

    Inputs:
    -   output_name: filename for the output gif (not including .gif file
        extension)
    -   output_dir: directory that the output gif will be saved to
    -   input_path_list: list of file names of images, each of which will form a
        single frame of the gif, in the order that they're specifed in the list.
        The file names should include the file extension (EG .png), as well as
        the directory name (if not in the current directory)
    -   duration: the duration each frame of the gif should last for, in
        milliseconds. Default is 100 seconds
    -   optimise: if True, attempt to compress the palette by eliminating unused
        colors. Default is False
    """
    first_frame = PIL.Image.open(input_path_list[0])
    if not os.path.isdir(output_dir):
        os.makedirs(output_dir)
    output_filename = "%s.gif" % output_name
    output_path = os.path.join(output_dir, output_filename)
    first_frame.save(
        output_path,
        format="gif",
        save_all=True,
        append_images=[PIL.Image.open(f) for f in input_path_list[1:]],
        loop=0,
        duration=duration,
        optimise=optimise
    )

def simple_plot(x, y, x_label, y_label, plot_name, dir_name, alpha):
    # Create figure and plot
    plt.figure(figsize=[8, 6])
    plt.plot(x, y, "bo", alpha=alpha)
    # Format, save and close the figure
    plt.title(plot_name)
    plt.xlabel(x_label)
    plt.ylabel(y_label)
    plt.tight_layout()
    plt.grid(True)
    if not os.path.isdir(dir_name):
        os.makedirs(dir_name)
    file_name = "%s.png" % plot_name
    full_path = os.path.join(dir_name, file_name)
    plt.savefig(full_path)
    plt.close()

n_frames = 10
x = np.linspace(0, 1, 100)
t = np.linspace(0, 1, n_frames, endpoint=False)
dir_name = "."
image_path_list = []
# First of all, save some image files to disk
for t_i in t:
    y = np.sin(2 * np.pi * (x - t_i))
    plot_name = "Test make gif, t = %.2f" % t_i
    simple_plot(x, y, "x", "y", plot_name, dir_name, 1)
    output_filename = "%s.png" % plot_name
    output_path = os.path.join(dir_name, output_filename)
    image_path_list.append(output_path)
# Now turn image files into a gif
make_gif("Test make gif", dir_name, image_path_list)

Test make gif.gif