I'm trying to display a grayscale image using matplotlib.pyplot.imshow(). My problem is that the grayscale image is displayed as a colormap. I need the grayscale because I want to draw on top of the image with color.
I read in the image and convert to grayscale using PIL's Image.open().convert("L")
image = Image.open(file).convert("L")
Then I convert the image to a matrix so that I can easily do some image processing using
matrix = scipy.misc.fromimage(image, 0)
However, when I do
figure() matplotlib.pyplot.imshow(matrix) show()
it displays the image using a colormap (i.e. it's not grayscale).
What am I doing wrong here?
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
Try to use a grayscale colormap?
E.g. something like
For a list of colormaps, see http://scipy-cookbook.readthedocs.org/items/Matplotlib_Show_colormaps.html