I think I understand it a little bit. With 8 keypoints this range is wider then with more keypoints. Also you can change the keypoint influence.
To make my question more clear: “Is there another way to have influence on the wideness of this range of colors changing to another range of colors?” I would like to have the possibility to change the wideness of this range, for each color seperately.
edit: So I am asking to have more influence on this interpolation for seperate source colors and target colors.