Publicity photo for City Lights...

with a photo from The Circus.

Note how Charlie only dyed the front part of his hair. His poorly done dye job is quite noticeable in certain scenes in the film, especially the tightrope scenes that were filmed after his divorce from Lita Grey, which evidently caused his already graying hair to turn even grayer (I disagree that his hair turned completely white as some of the books claim. It was still "salt and pepper" but with a little more salt added.)