title: A note on the marker-based watershed method for X-ray image segmentation.
abstract: OBJECTIVE
  A relatively new marker-based watershed method was proposed with international readership circulation. In this letter, we put forward a note on the use of max and min symbols in their study.
  
  
  METHODS
  We deduced the mathematical equations in their study.
  
  
  RESULTS
  We found the ``min'' operation should be changed to ``max'' in original Eqs. (1) and (5).
  
  
  CONCLUSIONS
  In spite of the two minor problems, the paper contains many important academic points.
authors.affiliation: Nanjing Normal University, Nanjing, Jiangsu 210023, PR China.
authors.forename: Siyuan
authors.initials: S
authors.lastname: Lu
authors.affiliation: Nanjing Normal University, Nanjing, Jiangsu 210023, PR China; Jiangsu Key Laboratory of Advanced Manufacturing Technology, Huaiyin, Jiangsu 223003, PR China.
authors.forename: Shuihua
authors.initials: S
authors.lastname: Wang
authors.affiliation: Nanjing Normal University, Nanjing, Jiangsu 210023, PR China. Electronic address: zhangyudong@njnu.edu.cn.
authors.forename: Yudong
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D014965:X-Rays
keywords: Direct radiography; Watershed segmentation; X-ray image