Recently an image-enhanced endoscopic technology using a pre-processor band-limited light called Optical Enhancement system (OE system™), was developed by HOYA Co. (Tokyo, Japan) and is now equipped with the latest endoscopy system (Pentax Video Processor EPK-i7010; HOYA Co.). This new technology combines digital signal processing in a similar way to I-scan and optical filters that limit the spectral characteristics of the illumination light. Previous I-scan technology uses white light alone as an illumination light and digital post-processing of the reflection afterwards creates images yielding the virtual chromoendoscopic image. Emission of white light alone causes a potential limitation for the current I-scan technology to obtain higher contrast images of microvascular pattern on the mucosal surface in combination with high magnification as shown by NBI with optical magnification. The basic concept of OE is to overcome the darkness of NBI witch results in less usefulness for detectability in wide-range observation in the gastrointestinal lumen. The new innovated optical filters achieve higher overall transmittance by connecting the peaks of the hemoglobin absorption spectrum (415 nm, 540 nm and 570 nm) creating a continuous wavelength spectrum. There are two modes with different OE filters (Mode 1 and Mode 2). Mode 1 is designed mainly to improve visualization of microvessels with a sufficient amount of light, and Mode 2 is designed to improve contrast of white-light observation by bringing the color tone of the overall image closer to that of natural color (white color tone) with much more light than that of the Mode 1 filter.