The following code will load an image from a file image.png and will display it as grayscale.
import numpy as np
import matplotlib.pyplot as plt
from PIL import Image
fname = ‘image.png’
image = Image.open(fname).convert(“L”)
arr = np.asarray(image)
plt.imshow(arr, cmap=’gray’, vmin=0, vmax=255)
plt.show()
If you want to display the inverse grayscale, switch the cmap to cmap=’gray_r’.
Try to use a grayscale colormap?
E.g. something like
imshow(…, cmap=pyplot.cm.binary)
For a list of colormaps, see http://scipy-cookbook.readthedocs.org/items/Matplotlib_Show_colormaps.html