How to convert 0-1 image float array to 0-255 int array

Question

import matplotlib
import numpy as np

photo=plt.imread('Feynman.png')
plt.figure
plt.subplot(121)
plt.imshow(photo)
photo*=255
plt.subplot(122)
plt.imshow(photo)

• Plot results in:
  • Clipping input data to the valid range for imshow with RGB data ([0..1] for floats or [0..255] for integers). and only displays an image in the first subplot

• Used image

Answer 1

• The issue is photo*=255 is still an array of floats.
  • Look at the photo array.
  • Add photo = photo.astype(int) after photo*=255.
  • X in .imshow should be int type when the array is 0-255: (M, N, 3): an image with RGB values (0-1 float or 0-255 int)

photo = plt.imread('Feynman.png')

fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(8, 5))

print(photo[0][0])

ax1.imshow(photo)

photo*=255

print(photo[0][0])

photo = photo.astype(int)

print(photo[0][0])

ax2.imshow(photo)

[output]:
[0.16470589 0.16470589 0.16470589]
[42. 42. 42.]
[42 42 42]