CORRECTION OF DISTORTION IN ENDOSCOPE IMAGES

Images formed with endoscopes suffer from a spatial distortion due to the wide-angle nature of the endoscope's objective lens. The distortio n causes areas in the image farther from the center of the field to ap pear significantly smaller than they really are. This change in the si ze of objects with position precludes quantitative measurement of the area of the objects. Quantitative area determinations are important in endoscopy for accurately measuring ulcer and lesion sizes over time, so that a need exists for correcting the distortion of the image. We p resent our method for correcting the distortion characteristic of endo scope images. A polynomial correction formula was developed for the en doscope lens and validated by comparing quantitative test areas before and after the distortion correction. The distortion correction has be en incorporated into a computer program that could readily be applied to electronic images obtained at endoscopy using a desk-top computer. The research presented here is a key step towards the quantitative det ermination of the area of regions of interest in endoscopy.