User requirement analysis is one of the most important steps in the design process of computer applications, and one of the very first. Based on a multi-purpose model of designing human interfaces, the U-T-S (User-Task-System) model, user characteristics and task analysis as analysis of user requirements are presented for a computer application in the visual arts area, the VASARI system. Viewing environment conditions are included as an additional feature. As a parsimonious and surveyable instrument, a table of user requirements including all relevant information from requirement analysis, and some requirements are compared with relevant conditions of the perceptual environment.