The invention relates to a medical observation device (1) such as a microscope or endoscope. Further, the invention relates to a method for processing medical images. Input image data (52) are generated by a visible-light camera (28) and overlaid with auxiliary input data (58) such as fluorescent-light image data (65) generated from auxiliary input data (58) e.g. a fluorescence camera (32) or an ultrasound sensor (40, 42). From the auxiliary input data (58), subsequent sets (84) of pseudo-color image data (86) are generated by an image processor (80). The pseudo-color images (84) are merged with the input image data (52) to obtain output image data (94). A pseudo-color pattern field (88) comprising at least one of a temporally and/or spatially modulated pattern (87) is generated depending on the content of at least one of the image input data (52) and the auxiliary input data (58).
