Image enhancement of surface micro-structure on mucosa for polarimetric endoscopy

摘要

This paper describes a novel image processing method for endoscopy that enhances the appearance of microstructures on mucosa. The new technique employs two pairs of parallel- and crossed-nicols polarimetric images, from which an averaged subtracted polarization image (AVSPI) is calculated. Experiments were first executed using a manual experimental setup with ring-type lighting, two rotating polarizers and a color camera. A new objective evaluation method that uses texture analysis (GLCM) was developed and applied to evaluation of the enhanced microstructure images. Experiments using excised porcine stomach tissue showed better results than with conventional color intensity image processing. Next, an online rigid-type polarimetric endoscope system using a polarized ring-shaped LED and a special three-CCD color polarimetric camera was developed. The two types of equipment described above are quite different as to extinction ratio values, but show similarly enhanced image quality. Our results show that polarimetric endoscopy is not only effective but also practical for hardware implementation.