We conducted a study of a newly developed "computed virtual chromoendoscopy" (CVC) system that enhances the contrast of the mucosal surface without the use of dyes. The CVC imaging technique is based on narrowing the bandwidth of the conventional endoscopic image arithmetically, using spectral estimation technology. Preliminary clinical tests comparing CVC-enhanced visualization of neoplastic and non-neoplastic lesions with images obtained by conventional endoscopy show that CVC enhances the vascular network as well as the pit pattern. CVC might therefore complement high-resolution endoscopy by facilitating the assessment of the nature and extent of gastrointestinal mucosal lesions.