Reverse colormap

reverse_cmap.py

from skimage import io as sio
import skimage

import numpy as np
import matplotlib
import matplotlib.pyplot as plt


img = skimage.img_as_float(sio.imread('im2.tif'))

jet = plt.cm.jet
jet._init()
lut = jet._lut[..., :3]

z = img - lut[:, None, None, :]
z *= z
d = z.sum(axis=-1)

out = d.argmin(axis=0)


f, (ax0, ax1, ax2) = plt.subplots(1, 3)
ax0.imshow(img, cmap=plt.cm.gray)
ax1.imshow(out, cmap=plt.cm.gray)
ax2.imshow(out, cmap=plt.cm.jet)

plt.show()