Abstract: Calibration device for a diagnostic device, the diagnostic device comprising a digital imaging device arranged to record an image of at least one sample container containing at least one biological sample. According to the invention, methods include of digitally imaging said at least one sample container, thus obtaining a first image processing the first image, thus obtaining a second image printing a representation of the second image onto a substrate by means of a printing method, thus obtaining the calibration device, wherein said processing of the first image comprises applying at least one transfer function to the first image. The invention further relates to a corresponding calibration device, and a method of calibrating a diagnostic device by means of the calibration device.