We have all decided which colors are by agreement. No one really knows what each other sees since seeing takes place in the brain,not the eye. You know how things look to you. That is your best guide for viewing. You can use a couple of hundred dollar disc, a shareware one or a THX setup. You could still get it wrong. The best dice about viewing and adjustment maximized to the lighting that you view in is great. If you watch TV at different times of the day or a whole family watches your TV then there is no one optimal adjustment. If you try to become a perfectionists at this, you will never get it right. Make sure the Reds don't bleed past their borders and that will give you a good start on the overall color adjustment. Look out your windows and see if you can match reality with what you see on your TV. That is the best way to calibrate.