A capture system comprising: a content capture mechanism (102; 302; 502) configured to capture image frames of an image containing a mark; an isolation engine (104; 304; 504) to identify mark data representing pixel values of covert data based on a first color channel data in the image frames captured by the content capture mechanism, the first color channel data of a first color channel having a pixel value emphasis to identify pixels associated with the mark; a mark strength engine (106; 306; 506) to divide the identified mark data into a number of regions, and evaluate strength change scores, wherein the strength represents detectability of the covert data in each region, by: identifying a first variance level in each region of the mark data of a first frame; identifying a second variance level of each region of the mark data of a second frame; determining a first strength score for each region of the mark data of the first frame based on the first variance level; determining a second strength score for each region of the mark data of the second frame based on the second variance level; and determining the strength change score for each of the number of regions from a corresponding difference between the first strength score and the second strength score; and a parameter controller (108; 308; 508) to adjust an exposure parameter of the content capture mechanism (102; 302; 502) in accordance with the strength change scores. a content capture mechanism (102; 302; 502) configured to capture image frames of an image containing a mark; an isolation engine (104; 304; 504) to identify mark data representing pixel values of covert data based on a first color channel data in the image frames captured by the content capture mechanism, the first color channel data of a first color channel having a pixel value emphasis to identify pixels associated with the mark; a mark strength engine (106; 306; 506) to divide the identified mark data into a number of regions, and evaluate strength change scores, wherein the strength represents detectability of the covert data in each region, by: identifying a first variance level in each region of the mark data of a first frame; identifying a second variance level of each region of the mark data of a second frame; determining a first strength score for each region of the mark data of the first frame based on the first variance level; determining a second strength score for each region of the mark data of the second frame based on the second variance level; and determining the strength change score for each of the number of regions from a corresponding difference between the first strength score and the second strength score; and identifying a first variance level in each region of the mark data of a first frame; identifying a second variance level of each region of the mark data of a second frame; determining a first strength score for each region of the mark data of the first frame based on the first variance level; determining a second strength score for each region of the mark data of the second frame based on the second variance level; and determining the strength change score for each of the number of regions from a corresponding difference between the first strength score and the second strength score; and a parameter controller (108; 308; 508) to adjust an exposure parameter of the content capture mechanism (102; 302; 502) in accordance with the strength change scores.