[Image-SIG] What colour model does the image use

[export at hope.cz]

I use im.getpixel((x,y)) to find out the colour of a pixel.
But how can I find out in which color model  the  the  return value is?

For example  for png picture format

im.getpixel((20,50))  gives the result 60.

What does the value mean?
Is it possible to find out the RGB model values?

Thank you for help.
L.