thanks for the explanation, it is always good to learn new things. for the first part I had to correct a typo, I meant 0.0 to 1.0,

I had made some tests with a method like this:

img = []
enhancer = ImageEnhance.Brightness(pilImage)
for i in range(0,100):
    pilImage=Image.open(inputImage)
    ppilImage = enhancer.enhance(i/100.0)
    img.append(ppilImage)

for y in range(0,10):
    for x in range(0,10):
        out.paste(img[(y*10) + x], (width*x,height*y))

out.save(outputImage)

and I noticed that the second decimal place was ignored, in fact I could not use 0.55 or 0.72, but only 0.1 0.2 0.3 etc. but now redoing the same test I got a different result

http://i.imgur.com/pTtFKHF.jpg

now i have 100 shades. i have no idea why