Where did you get the photo retouching info on this? The only photo retouching is the one photo your showing and that was done for the 2011 film of for Battle: Los Angeles, the original one from the 40s has been proven authentic and untouched by numerous labs. Kind of confused lol...are you meaning the producers of the film are trying to lay claim that photo was a hoax when it wasn't? Here is the original untouched photo from the 40s that is untouched, that above is the one the film makers recreated and touched up for the film:

I have actually done a lot of research on this over the years. Biggest key thing isn't about the news reports its the eye witness accounts from the soldiers and citizens that witnessed the thousands of rounds being fired off. Not one said it was weather balloon, most thought it was secret military aircraft, possibly the Japanese military which kind of ruled out for me even a remote chance at minimum a weather balloon was involved. Think about it this way, back then ammo was scarce due to the wars we had, military officials know a weather balloon due to working with them, why would they all freak out and fire so many wasted rounds on a suspected weather balloon?

Not sure what source you got about a retouched photo from the 40s but I dug just in case I missed something and all that pops up was the film makers for the 2011 film recreated the photo for the film due to the grain issues in the picture. So that photo above isn't the original at all, a recreation.

This is that same very photo taken from the Battle: Los Angeles IMDB

Compare the original and the recreation, totally different photos