The risk for colon cancer in patients with longstanding ulcerative colitis exceeding the rectum is increased and therefore patients should be enrolled in a surveillance program eight years after the diagnosis. Until today, official international guidelines for endoscopic screening in patients with ulcerative colitis advise to take 4 biopsies every 10 centimeters (with a minimum of 32) and of each suspected visible lesion. These guidelines are merely based on consensus during expert opinion meetings rather than evidence based. Recent studies have shown that chromo-endoscopy guided biopsies significantly reduced the number of biopsies for each procedure and detected more neoplastic lesions. Chromo-endoscopy is therefore considered the gold standard in this study in which we want to compare it to the performance and efficiency of new endoscopic imaging techniques. Narrow-Band Imaging (NBI) selectively uses certain wavelengths of the visible light leading to a shift in the excitation spectrum towards blue light. The first studies with NBI showed that the additional value of NBI in the detection of neoplastic lesions is comparable to chromo-endoscopy, but time saving and easier to perform. The Fujinon Intelligent Chromo-Endoscopy (FICE) system uses a similar theoretical principal as NBI but this is achieved via the use of post hoc computer algorithms, applying different filters to the stored endoscopic images and enabling a theoretically endless number of combinations of filters that can be used. The Pentax I-scan system also allows post hoc modification of the images. On the one hand, surface enhancement enables to better highlight mucosal changes. Spectral modification allows to apply different modes in analogy with to FICE system. These new imaging techniques have a theoretical advantage which is extendedly used for sales purposes but has however so far not been proven in ulcerative colitis patients. We want to test their clinical use in the screening for neoplastic lesions in patients with long standing ulcerative colitis.