The invention relates to a system for visualizing characteristic tissue with a colorant in a surgical region. The system contains a detection unit which detects light from at least one object point in the surgical region. The system has a computer unit which is connected to the detection unit and drives a visualization unit which displays an image of an area in the surgical region. The computer unit determines the color coordinate in a color space with respect to the light from a point from the object point in the surgical region. Depending on the position of the color coordinate determined with respect to the object point, the computer unit calculates a color coordinate information (“0”, “1”) for controlling the visualization unit by comparing information concerning the determined color coordinate of the object point with information concerning a characteristic reference color coordinate.