i completely agree with you we cannot expect aliens to interpret pictures movies sound and text the way we do even if they would be able to see the same spectrum as us it remains doubtful if those images will mean anything to them at first glance however the point here is to convey information while we can look at a picture at all wavelengths it is only in the visible spectrum that information on this picture patterns and variations start to appear at other wavelengths its blank an analogy would be satellites using sars to pierce the cloud cover of venus and image its surface there is little information in the visible spectrum but lots outside of it if the information is encoded in a digital form eg rgb rather than displayed using our technology then they will interpret it in colors they can see as this encoding is not relative to a specific spectrum still they should be able to figure out what king of colors we meant to encode in the first place by looking at the probes themselves and the markings on them i think that the aliens will be able to make sense of this information easily regardless i completely agree with you it will take them years to analyze what we have sent them and make sense of it ie convert it to something they can relate to but if they feel as lonely as us then i trust that they will invest the resources and time