The present disclosure relates to a supplementary device for attachment to an injection device including an imaging arrangement configured to capture an image of a moveable number sleeve of the injection device, a plurality of light sources, and a processor arrangement configured to control operation of the imaging arrangement and the plurality of light sources and to receive image data from the imaging arrangement. In some instances, the processor arrangement is configured to activate the plurality of light sources sequentially and to combine multiple images captured by the imaging apparatus under different illumination conditions into a single image.
