Abstract: The disclosure relates to a method for optically inspecting at least partially transparent objects, in particular pharmaceutical containers, wherein a first and a second image of an object to be inspected are captured, wherein, for this purpose, the object is captured and/or illuminated from different angles, wherein the images differ from one another on the basis of the angular offset, wherein an abnormality in the second image is identified, wherein a mask is calculated based on the identified abnormality and the mask is applied to the first image in order to obtain a masked image of the object, and wherein the masked image is analysed to identify abnormalities in an inspection region of the object. The disclosure further relates to a corresponding inspection device and to a set for retrofitting an existing inspection device.