An image processing device (100) for a medical observation device (102), such as a microscope (104) or endoscope, is disclosed. The image processing device (100) comprises an image processor (106). The image processor (106) is configured to obtain a digital pseudocolor pattern (116), which has a pattern characteristic (118) and comprises a pseudocolor (120). The image processor (106) is further adapted to combine the digital pseudocolor pattern (116) with an input area (122) of retrieved digital input image (108, 110), thus forming a patterned region (124). Moreover, the image processor (106) is adapted to vary the pattern characteristic at a location (126) in the patterned region (124) depending on one of the intensity (I) and brightness (B) at a corresponding location (128) in the input area (122) of at least one of the digital input images (108, 110) and retrieved digital input image (108, 110); and to output at least one digital output image (130) comprising the patterned region (124).