I would like to buy a few color filters 81A and 82A. And I found the Cokin system very flexible. However, the salesperson told me that most people using Cokin would only buy their funny filters. For serious use, like polarizer and color correction filters, the common glass filter would be more preferred. My questions: 1. Are those Cokin polarizer, ND, gradual and color filters quality good enough to be used? 2. I would scan all my film into computer for processing instead of printing out. Should I make the color correction with my PC instead of those color filters?