We all tend to think that photo manipulation, cosmetic touch ups, etc. are all a product of the last few years and only possible in the computer age as we now all know it with the advent of Photoshop and other technologies. Nothing could be further from the truth.
There is a Chevrolet advertisement from 1969 with the picture of a '69 Camaro base convertible, as I recall the car was yellow (not sure if the yellow was Daytona or Butternut yellow) that was very prominently used as advertising "back in the day". I'm sure that many of you would recognize the picture I'm referring to if you saw it. Thought I had a copy of it somewhere, but at the moment it escapes me. If I can find it, I'll post it.
In any event, there are two versions of that picture - one from early in the '69 production year and one later (post Jan 1969). The difference is that the early production picture shows an engine front fender badge of "327" an the late production picture shows a front fender badge of "307". Obviously the same picture, the latter being the first picture "touched up" to reflect the base V8 engine change in Jan '69 from 327 to 307 cid.
I would consider any advertising or promotional pictures as just that - as stated previousy, they may or may not reflect production reality. Although it was much more difficult in 1968-69, photo manipulation and "touch up" was not unheard of - just done manually by the artist's hand instead of electronically by the computer.