show multiple image in matplotlib from numpy array

Question

I have an array with the shape (1, 64, 224, 224). 64 Single channel images of size 224*224. When I do this:

plt.imshow(output_image[0,1,:,:], interpolation='nearest')

The image is displayed properly.

But when I do:

for i in range(64):
    plt.imshow(output_image[0,i,:,:], interpolation='nearest')

I see only 1 image as result even though there are 64 images.

How can I get a line of 64 images? What am I doing wrong?

You need to use the extent kwarg to move them from overlapping. — tacaswell
– tacaswell, Commented Jan 2, 2017 at 19:56
@tacaswell Thanks! I am new to Python , an example of how I might do this will be nice — Abhik
– Abhik, Commented Jan 2, 2017 at 20:02

Mike Müller · Accepted Answer · 2017-01-02 20:13:37Z

9

You can create a new subplot for each image:

fig = plt.figure(figsize=(50, 50))  # width, height in inches

for i in range(64):
    sub = fig.add_subplot(64, 1, i + 1)
    sub.imshow(output_image[0,i,:,:], interpolation='nearest')

This will put all 64 images in one column. Change to:

sub = fig.add_subplot(8, 8, i + 1)

for eight columns and eight rows.

edited Jan 2, 2017 at 20:13

answered Jan 2, 2017 at 20:04

Mike Müller

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2 Comments

Abhik Over a year ago

This works ! but the images are really small . The original image is 224*224 quite big. How do i increase the image size in the plot ?

Mike Müller Over a year ago

You can specify a figure size. See my updated answer.

Sakhri Houssem · Accepted Answer · 2018-03-15 16:24:14Z

1

this function creates subplot for each image:
the img has shape of (n,height,width,channel)

import numpy as np
def picshow(img):
    num = len(img)
    ax = np.ceil(np.sqrt(num)) 
    ay = np.rint(np.sqrt(num)) 
    fig =plt.figure()
    for i in range(1,num+1):
        sub = fig.add_subplot(ax,ay,i)
        sub.set_title("titre",i)
        sub.axis('off')
        sub.imshow(data[i-1])
    plt.show()

edited Mar 15, 2018 at 16:24

answered Mar 13, 2018 at 21:08

Sakhri Houssem

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