Newspapers have 1000s of pages to print in every run, so, images are created in the most economical way possible, using the latest techniques available (but generally offset lithography). Images printed this way are comprised of a dots and shapes of varying sizes. With a small magnifier, you can easily see this pattern.
There is very little that can be done to clean up this type of print/image for wide format, or mural printing. For a recent project, I delivered the below. I changed the color to a crisper, non-sepia tone color, I deleted the background and replaced it with a consistent dot pattern background that mimics the print dot size, and I adjusted dot color in the FULL black areas. Optionally, I could have hired a portrait artist to paint over the image (I keep a plethora of designers with varied skills close by), but that was not an acceptable reproduction method for the customer.