Display multiple images in one IPython Notebook cell?

Question

If I have multiple images (loaded as NumPy arrays) how can I display the in one IPython Notebook cell?

I know that I can use plt.imshow(ima) to display

Answer 1

If you don't mind an additional dependency here is a two liner using scikit-image:

from skimage.util import montage
plt.imshow(montage(np.array(images), multichannel=True))

Set multichannel=True for color images and multichannel=False for grayscale images.

Answer 2

You can do it really fast and easy with IPyPlot:

import ipyplot

ipyplot.plot_images(images_array, max_images=20, img_width=150)

You would get a plot similar to this:

It's using IPython.display and HTML under the hood and it can take images in following formats:

• string file paths
• PIL.Image objects
• numpy.ndarray objects representing images

It would take just a few seconds to display a numpy array of 500 images

Answer 3

Horizontal layout

Short answer

plt.figure(figsize=(20,10))
columns = 5
for i, image in enumerate(images):
    plt.subplot(len(images) / columns + 1, columns, i + 1)
    plt.imshow(image)

Long answer

import glob
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
%matplotlib inline

images = []
for img_path in glob.glob('images/*.jpg'):
    images.append(mpimg.imread(img_path))

plt.figure(figsize=(20,10))
columns = 5
for i, image in enumerate(images):
    plt.subplot(len(images) / columns + 1, columns, i + 1)
    plt.imshow(image)

Answer 4

You can display multiple images in one IPython Notebook cell by using display and HTML functions. You need to create the set of html img tags as a string as follows

from IPython.display import Image, HTML, display
from glob import glob
imagesList=''.join( ["<img style='width: 120px; margin: 0px; float: left; border: 1px solid black;' src='%s' />" % str(s) 
                 for s in sorted(glob('yourimage*.png')) ])
display(HTML(imagesList))

See a example of use from http://nbviewer.ipython.org/github/PBrockmann/Dodecahedron

You may need to refresh your browser (shift + load) to see new images if they have been changed from a previous cell.

Answer 5

based on @ChaosPredictor answer

from matplotlib.pyplot import figure, imshow, axis
from matplotlib.image import imread

def showImagesMatrix(list_of_files, col=10, wSize=5, hSize=5, mypath='.'):
    fig = figure(figsize=(wSize, hSize))
    number_of_files = len(list_of_files)
    row = number_of_files / col
    if (number_of_files % col != 0):
        row += 1
    for i in range(number_of_files):
        a=fig.add_subplot(row, col, i + 1)
        image = imread(mypath + '/' + list_of_files[i])
        imshow(image, cmap='Greys_r')
        axis('off')

then

from pathlib import Path
p = Path('.')
num_images = 30
list_of_image_paths = [str(x) for x in list(p.glob('../input/train/images/*'))[:num_images]]

showImagesMatrix(list_of_image_paths)

# or with named args
showImagesMatrix(list_of_image_paths, wSize=20, hSize=10, col=5)

Answer 6

Short answer:

call plt.figure() to create new figures if you want more than one in a cell:

for ima in images:
    plt.figure()
    plt.imshow(ima)

But to clarify the confusion with Image:

IPython.display.Image is for displaying Image files, not array data. If you want to display numpy arrays with Image, you have to convert them to a file-format first (easiest with PIL):

from io import BytesIO
import PIL
from IPython.display import display, Image

def display_img_array(ima):
    im = PIL.Image.fromarray(ima)
    bio = BytesIO()
    im.save(bio, format='png')
    display(Image(bio.getvalue(), format='png'))

for ima in images:
    display_img_array(ima)

A notebook illustrating both approaches.