Getting started Image processing python

[Vindhyachal Takniki]

1. I want to learn basic image processing in python. (working on raspberry pi 2 board)

2. I have a image with different color dots like red,white, etc.After taking image, need to identify how many are red,white etc. 
I am looking for free image processing libs for that. Which one is better for begineers : http://scikit-image.org/download.html  or http://opencv-python-tutroals.readthedocs.org/en/latest/index.html ?