Quantitative endoscopic classification of esophagitis by means of computerized image processing. Part 1: Theoretical background.

The potential sources of error for quantitative mapping of pathological areas in tubular organs are investigated mathematically and discussed. The first of the main errors stems from a predominance of red in the illuminating light reflected and re-reflected from the side wall of the tubular organ as compared with the white illuminating light coming directly from the light source in the endoscope. A mathematical model for this has been constructed to define an allowed interval of observation distance. The second error is due to geometrical projection, and results from the fact that more distant parts of the inside of a tube subtends a smaller solid angle than closer parts.