What is a .COL file: a .col file is a minecraft color plate file used for console and maybe soon windows 10 edition where it allows in a resource pack for environmental colors to be changed. If you have the ability to change these colors in your own resource pack / dlc you bought then this is the tool for you.
Why do I need to view/edit Color Plate File: You need to view it if your cursious about the colors of the dlc/custom resource pack you got for console edition and you need to edit it for just the fun of it. In your favorite resource pack why not make the sky purple in a specific biome such as the plains for example.
Where is the .COL file located: The .col file is located in the .pck file of the resolution of your texture pack. Use ravioli explorer to extract it. If you don't see directories contact me I have the plugin if the creator hasn't released it yet.
For a converter to conver .col to .txt or .csv (if you ever find the need for that) check here: