Here is an example of photographic alteration from history. In 1939, Hitler and Stalin agreed upon a Russian-German Non-Agression pact. And as you know, it didn't hold, and in less than two years, they were at war.
But in August 1939, Hitler sent a team to Moscow to sign the documents and have a formal ceremony. And it included his personal photography, Heinrich Hoffman. For some reason, Hitler didn't go himself. Maybe he didn't like to travel. But, he instructed Hoffman to take as many photos of Stalin as he could.
And Hoffman complied, capturing over 60 images. However, in every single one of them, Stalin was sporting a cigarette.
That didn't go over too well with Hitler, who was a non-smoker. He didn't like smoking. And he thought it was an insult to the German people that Stalin conducted the ceremony while smoking. He felt it reduced the solemnity of the occasion.
So, Hitler instructed Hoffman to either throw them out or do something to remove the cigarettes from the images. And Hoffman did the latter.
This is probably the most famous image from the occasion. It was taken by Hoffman's assistant, and Hoffman is the one toasting his glass with Stalin. Stalin's left hand actually harbored a cigarette. But, Hoffman did the retouching to remove it, and this was the result:
So, if things like this could be done in 1939, I dare say they could alter the Altgens photo in 1963.