Fig 7From: Assessing clarity and erasability of commercially available pens for surgical site marking: a comparative study in human volunteersDemonstrate the relationship between the observer data and the grayscale data comparing the PREP parameter from the grayscale data (0–1) to the synonymous change in percentage clarity parameter from the observer data (1–100 %) for the upper and lower limb sites respectively. The unity line represents complete agreement between the two sets of dataBack to article page