importmatplotlibprintmatplotlib.__version__## 1.5.0importmatplotlib.imageasima=im.imread('lena.jpg')print'a: ',a.min(),a.max(),a.dtype## a:  0 255 uint8# This works fineim.imsave('test0.png',a)# vmin and vmax are ignored. Expected a saturated imageim.imsave('test1.png',a,vmin=0,vmax=128)a_expected=a.astype('float')/128im.imsave('test1_expected.png',a_expected)b=a.astype('float')print'b: ',b.min(),b.max(),b.dtype## b:  0.0 255.0 float64# imsave should use b.min() and b.max() as limits.im.imsave('test2.png',b)im.imsave('test2_expected.png',b/255)# vmin and vmax are ignored. Expected an image equal to the originalim.imsave('test3.png',b,vmin=0,vmax=255)im.imsave('test3_expected.png',b/255)c=b/b.max()print'c: ',c.min(),c.max(),c.dtype##c:  0.0 1.0 float64# This works fineim.imsave('test4.png',c)# vmin and vmax are ignored. Expected a saturated imageim.imsave('test5.png',c,vmin=0,vmax=0.5)im.imsave('test5_expected.png',c*2)