CODEWITHSUNDEEP
numpymatplotlibimage-processingpython-imaging-library
Manik
Manik

Reputation: 595

png file shows bluish image when using plt.imshow()

I'm trying to plot a png file using matplotlib.pyplot.imshow() but it's showing a bluish image(see below). It works for jpeg file but not for png.

This is the code:

import matplotlib.pyplot as plt
import numpy as np
from PIL import Image
im = Image.open('apple_logo.png')
im.save('test.png') #test.png is same as original
data = np.array(im)
print(data) 
plt.imshow(data) #shows a bluish image of the logo

The image i'm using:

apple_logo image i'm using

bluish image:

bluish image of the apple_logo

Python 3.8.2
matplotlib 3.3.0
Pillow 7.2.0
numpy 1.19.0
OS: Windows 10

Upvotes: 1

Views: 609

Answers (1)

Warren Weckesser
Warren Weckesser

Reputation: 114976

The original PNG image is an indexed PNG file. That is, it has a palette (i.e. a lookup table for the colors), and the array of data that makes up the image is an array of indices into the lookup table. When you convert im to a numpy array with data = np.array(im), data is the array of indices into the palette, instead of the array of actual colors.

Use the convert() method before passing the image through numpy.array:

data = np.array(im.convert())

Upvotes: 2

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