Ulcerative colitis is an idiopathic inflammatory disorder affecting the mucosa of the colon with superficial erosions and ulcers associated with bleeding. Severity assessment using current scoring schemes such as UCEIS and MAYO relies on the subjective interpretation of the physician and fails to take into account the size of the different lesions, their number and their distribution throughout the colon. Automatic lesion detection and grading procedures can enable fine-grained assessment of lesion severity for treatment follow-up.