Photographs as historical records are invaluable. But, much before Adobe gave us Photoshop, political establishments have been liberally airbrushing people out of photographs, to suit their version of history. I came across this extremely interesting photo-gallery created by Time Magazine which shows how doctoring of photographs has been around since early years of photography.
Particularly interesting in these is the picture of Vladimir Lenin addressing the Russian troops before they left for Poland in 1920. During the Stalin era, two principal rivals of Stalin, Trotsky and Kramenev, were airbrushed from this widely published archival picture. This doctored picture was printed and reprinted right up to Gorbachev's time!
Another one is of Hitler, and the missing Gobbels who was evaporated awkwardly by the regime. Even weirder are instances of ultra-orthodox Israeli newspaper eliminating women cabinet members of Benjamin Netanhyu, and Paul McCartney losing his cigarette in the famous Beatles quartet walking down the Abbey Road picture.
Found another doctoring gem from Stalin era on Wikipedia. One moment you see Yezhov and another you don't.