Two-step iterative registration for 2D-gel electrophoresis images

2D-Gel Electrophoresis (2D-GE) is a central technique for separation of protein samples in proteomic research. A 2D-GE image usually contains hundreds of protein spots that should be detected by an image processing technique. Identifying the missing proteins by comparison of two samples such as from healthy person and patient can be helpful in developing medicine or disease control. This matching process is a laborious work that needs to be automatically done by computers with less user intervention as much as possible. In this paper, we propose a two-step iterative registration algorithm for protein spots in 2D-GE images. The algorithm estimates the geometrical differences between the corresponding landmarks and iteratively moves the spot points in the matched gel in order to be closer to its correspondence in the reference gel. The amount of movement of each spot is affected by the Euclidian distances from the spot to all landmarks. The single-step matching is defined with its pros and cons; then the motivation to a two-step iterative registration algorithm and its results are discussed.