The Vector Scope is essentially used to measure color. It is a circular measuring device the breaks up the color spectrum into six areas: Red, Magenta, Blue, Green, Cyan, and Yellow. When your image is being measured on the vector scope you will have a complex machine of indicated lines and points that will inevitably migrate slightly into the direction that your color is in. For example, if there is a large amount of green in your image or the entire image has a green tint it will be much close to the Green section of the vectorscope.