Autofluorescence of the tumor and surrounding tissue is the largest background source in fluorescence diagnosis. A new system which applied computer image processing technique to lung cancer localization by laser fluorescence bronchoscopy has been developed to subtract the autofluorescence background. The results of our trial tests in tissue- simulating phantom and the porcine thigh muscle models are satisfied. There is great hope that this computer-assisted image processing system will significantly enhance the contrast of fluorescence image and drop false results for early human lung cancer examination.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.