In an example, a capture system includes a content capture mechanism, an isolation engine, a mark strength engine, and a parameter controller. In that example, the isolation engine generates mark data, the mark strength engine identifies a first variance level in a first region of a first set of mark data, and the parameter controller adjusts a parameter of the content capture mechanism in accordance with a strength change based on a comparison of the first variance level to a second variance level in a first region of a second set of mark data.