CODEWITHSUNDEEP
pythonmatplotlibimshowsavefig
Ahmet Tuğrul Bayrak
Ahmet Tuğrul Bayrak

Reputation: 3786

Removing white space around a saved image

I need to take an image and save it after some process. The figure looks fine when I display it, but after saving the figure, I got some white space around the saved image. I have tried the 'tight' option for savefig method, did not work either. The code:

import matplotlib.image as mpimg
import matplotlib.pyplot as plt

fig = plt.figure(1)
img = mpimg.imread("image.jpg")
plt.imshow(img)
ax = fig.add_subplot(1, 1, 1)

extent = ax.get_window_extent().transformed(fig.dpi_scale_trans.inverted())
plt.savefig('1.png', bbox_inches=extent)

plt.axis('off') 
plt.show()

I am trying to draw a basic graph by using NetworkX on a figure and save it. I realized that without a graph it works, but when added a graph I get white space around the saved image;

import matplotlib.image as mpimg
import matplotlib.pyplot as plt
import networkx as nx

G = nx.Graph()
G.add_node(1)
G.add_node(2)
G.add_node(3)
G.add_edge(1, 3)
G.add_edge(1, 2)
pos = {1:[100, 120], 2:[200, 300], 3:[50, 75]}

fig = plt.figure(1)
img = mpimg.imread("image.jpg")
plt.imshow(img)
ax = fig.add_subplot(1, 1, 1)

nx.draw(G, pos=pos)

extent = ax.get_window_extent().transformed(fig.dpi_scale_trans.inverted())
plt.savefig('1.png', bbox_inches=extent)

plt.axis('off') 
plt.show()

Upvotes: 349

Views: 349526

Answers (16)

P. Rathje
P. Rathje

Reputation: 118

I usually need to crop whitespace from PDF files for scientific papers. Tweaking matplotlib to truly remove all the whitespace never worked perfectly, and some whitespace remained… If you are using pdflatex, the included pdfcrop executable proved very useful to remove whitespace from exported figures. Hence, after exporting the PDF, pdfcrop removes remaining whitespace. Here is a Python snippet to automatically crop your saved figure using pdfcrop. Just call the function instead of plt.savefig:

import subprocess
import os

def save_and_crop(path, *args, **kwargs):
    filename, file_extension = os.path.splitext(path)
    plt.savefig(path, *args, **kwargs)
    if file_extension == ".pdf":
        cropped_path = filename + "_cropped" + file_extension
        subprocess.run(["pdfcrop", path, cropped_path], stdout=subprocess.DEVNULL)

Upvotes: 0

Kolibril
Kolibril

Reputation: 1423

In a Jupyter notebook, one can add this line:

%config InlineBackend.print_figure_kwargs = {'pad_inches':0}

Here is a minimal example

import matplotlib.pyplot as plt
import numpy as np

%config InlineBackend.print_figure_kwargs = {'pad_inches':0}

fig, ax = plt.subplots()
ax.axis("off")
ax.imshow(np.fromfunction(lambda i, j: np.sin(j), (15, 15)), cmap="YlGnBu")

enter image description here

Upvotes: 2

Razorocean
Razorocean

Reputation: 398

So the solution depend on whether you adjust the subplot. If you specify plt.subplots_adjust (top, bottom, right, left), you don't want to use the kwargs of bbox_inches='tight' with plt.savefig, as it paradoxically creates whitespace padding. It also allows you to save the image as the same dims as the input image (600x600 input image saves as 600x600 pixel output image).

If you don't care about the output image size consistency, you can omit the plt.subplots_adjust attributes and just use the bbox_inches='tight' and pad_inches=0 kwargs with plt.savefig.

This solution works for matplotlib versions 3.0.1, 3.0.3 and 3.2.1. It also works when you have more than 1 subplot (eg. plt.subplots(2,2,...).

def save_inp_as_output(_img, c_name, dpi=100):
    h, w, _ = _img.shape
    fig, axes = plt.subplots(figsize=(h/dpi, w/dpi))
    fig.subplots_adjust(top=1.0, bottom=0, right=1.0, left=0, hspace=0, wspace=0) 
    axes.imshow(_img)
    axes.axis('off')
    plt.savefig(c_name, dpi=dpi, format='jpeg')

Upvotes: 3

Keto
Keto

Reputation: 2177

The most straightforward method is to use plt.tight_layout transformation which is actually more preferable as it doesn't do unnecessary cropping when using plt.savefig

import matplotlib as plt    
plt.plot([1,2,3], [1,2,3])
plt.tight_layout(pad=0)
plt.savefig('plot.png')

However, this may not be preferable for complex plots that modifies the figure. Refer to Johannes S's answer that uses plt.subplots_adjust if that's the case.

Upvotes: 19

Mohammed
Mohammed

Reputation: 2701

This worked for me plt.savefig(save_path,bbox_inches='tight', pad_inches=0, transparent=True)

Upvotes: 18

user1410665
user1410665

Reputation: 759

You may try this. It solved my issue.

import matplotlib.image as mpimg
img = mpimg.imread("src.png")
mpimg.imsave("out.png", img, cmap=cmap)

Upvotes: 0

Johannes S.
Johannes S.

Reputation: 3104

I cannot claim I know exactly why or how my “solution” works, but this is what I had to do when I wanted to plot the outline of a couple of aerofoil sections — without white margins — to a PDF file. (Note that I used matplotlib inside an IPython notebook, with the -pylab flag.)

plt.gca().set_axis_off()
plt.subplots_adjust(top = 1, bottom = 0, right = 1, left = 0, 
            hspace = 0, wspace = 0)
plt.margins(0,0)
plt.gca().xaxis.set_major_locator(plt.NullLocator())
plt.gca().yaxis.set_major_locator(plt.NullLocator())
plt.savefig("filename.pdf", bbox_inches = 'tight',
    pad_inches = 0)

I have tried to deactivate different parts of this, but this always lead to a white margin somewhere. You may even have modify this to keep fat lines near the limits of the figure from being shaved by the lack of margins.

Upvotes: 308

SuaveSouris
SuaveSouris

Reputation: 1342

After trying the above answers with no success (and a slew of other stack posts) what finally worked for me was just

plt.gca().set_axis_off()
plt.subplots_adjust(top = 1, bottom = 0, right = 1, left = 0, 
            hspace = 0, wspace = 0)
plt.margins(0,0)
plt.savefig("myfig.pdf")

Importantly this does not include the bbox or padding arguments.

Upvotes: 41

Khan
Khan

Reputation: 1498

i followed this sequence and it worked like a charm.

plt.axis("off")
fig=plt.imshow(image array,interpolation='nearest')
fig.axes.get_xaxis().set_visible(False)
fig.axes.get_yaxis().set_visible(False)
plt.savefig('destination_path.pdf',
    bbox_inches='tight', pad_inches=0, format='pdf', dpi=1200)

Upvotes: 9

Simon Thomas
Simon Thomas

Reputation: 187

For anyone who wants to work in pixels rather than inches this will work.

Plus the usual you will also need

from matplotlib.transforms import Bbox

Then you can use the following:

my_dpi = 100 # Good default - doesn't really matter

# Size of output in pixels
h = 224
w = 224

fig, ax = plt.subplots(1, figsize=(w/my_dpi, h/my_dpi), dpi=my_dpi)

ax.set_position([0, 0, 1, 1]) # Critical!

# Do some stuff
ax.imshow(img)
ax.imshow(heatmap) # 4-channel RGBA
ax.plot([50, 100, 150], [50, 100, 150], color="red")

ax.axis("off")

fig.savefig("saved_img.png",
            bbox_inches=Bbox([[0, 0], [w/my_dpi, h/my_dpi]]),
            dpi=my_dpi)

enter image description here

Upvotes: 4

Parth92
Parth92

Reputation: 379

A much simpler approach I found is to use plt.imsave :

    import matplotlib.pyplot as plt
    arr = plt.imread(path)
    plt.imsave('test.png', arr)

Upvotes: 6

TomNorway
TomNorway

Reputation: 3162

The following function incorporates johannes-s answer above. I have tested it with plt.figure and plt.subplots() with multiple axes, and it works nicely.

def save(filepath, fig=None):
    '''Save the current image with no whitespace
    Example filepath: "myfig.png" or r"C:\myfig.pdf" 
    '''
    import matplotlib.pyplot as plt
    if not fig:
        fig = plt.gcf()

    plt.subplots_adjust(0,0,1,1,0,0)
    for ax in fig.axes:
        ax.axis('off')
        ax.margins(0,0)
        ax.xaxis.set_major_locator(plt.NullLocator())
        ax.yaxis.set_major_locator(plt.NullLocator())
    fig.savefig(filepath, pad_inches = 0, bbox_inches='tight')

Upvotes: 18

Richard Yu Liu
Richard Yu Liu

Reputation: 119

I found the following codes work perfectly for the job.

fig = plt.figure(figsize=[6,6])
ax = fig.add_subplot(111)
ax.imshow(data)
ax.axes.get_xaxis().set_visible(False)
ax.axes.get_yaxis().set_visible(False)
ax.set_frame_on(False)
plt.savefig('data.png', dpi=400, bbox_inches='tight',pad_inches=0)

Upvotes: 11

Alejandro Sazo
Alejandro Sazo

Reputation: 795

This works for me saving a numpy array plotted with imshow to file

import matplotlib.pyplot as plt

fig = plt.figure(figsize=(10,10))
plt.imshow(img) # your image here
plt.axis("off")
plt.subplots_adjust(top = 1, bottom = 0, right = 1, left = 0, 
        hspace = 0, wspace = 0)
plt.savefig("example2.png", box_inches='tight', dpi=100)
plt.show()

Upvotes: -4

unclerico
unclerico

Reputation: 445

I found something from Arvind Pereira (http://robotics.usc.edu/~ampereir/wordpress/?p=626) and seemed to work for me:

plt.savefig(filename, transparent = True, bbox_inches = 'tight', pad_inches = 0)

Upvotes: 32

Hooked
Hooked

Reputation: 88118

You can remove the white space padding by setting bbox_inches="tight" in savefig:

plt.savefig("test.png",bbox_inches='tight')

You'll have to put the argument to bbox_inches as a string, perhaps this is why it didn't work earlier for you.

Possible duplicates:

Matplotlib plots: removing axis, legends and white spaces

How to set the margins for a matplotlib figure?

Reduce left and right margins in matplotlib plot

Upvotes: 398

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