Jet is discouraged for MRI images. Google Image Search shows the vast majority are grayscale http://www.research.ibm.com/dx/proceedings/pravda/truevis.htm

endolith · endolith · commit 9614b1155c2a · 2012-05-31T01:04:18.000-03:00
diff --git a/examples/pylab_examples/mri_demo.py b/examples/pylab_examples/mri_demo.py
@@ -10,7 +10,7 @@
 im.shape = 256, 256
 
 #imshow(im, ColormapJet(256))
-imshow(im, cmap=cm.jet)
+imshow(im, cmap=cm.gray)
 axis('off')
 
 show()
