For simplified, less computationally intensive, image recording of different spectral signal components using a plurality of color channels of a single image sensor, a targeted adjustment of a sensitivity of at least one of the color channels in relation to another one of the color channels of the image sensor is provided for a spectral separation of this reduced or adjusted color channel from the other color channel so that at least one certain spectral range (i.e., in particular a part of a first spectral range captured using the other color channel) is no longer detectable using the color channel that has been adjusted in terms of its sensitivity. This adjusted color channel becomes spectrally blind in the spectral range and can consequently spectrally selectively detect a further spectral range (specifically a second spectral range deviating from the first spectral range). The second spectral range may include a fluorescence wavelength.