Some filters have always been required for monochrome film stock. Ultraviolet for use in snow areas cut down excessive glare, and the yellow K2 improved sky contrast as clouds had a tendency to wash out. Use of color introduced us to the Skylight 1a and1b, polarizing filter and graduated color filters, gray making for a more imposing, dramatic sky, and tobacco giving a softer 'sunset' look. There followed a plethora of filter effects, one of which stands out as owners of such a filter inevitably always abused it. The reference here is to the dreaded 'starburst' filter, able to put a multiple point star on every surface having a strong light source coming from it. Stars, stars, stars, stars everywhere, four point, six point, eight point. Aarrghhh.
The photo to the left of a young girl, circa 1940, has no obvious visual effects applied other than skillful lighting and the ability of the photograher to get a good dreamy, innocent 'pose' so reminiscent of the era. That is not to say that it has not been manipulated since, but it is a good example of classic monochrome portraiture, and works better because of it. The various elements within the photo are not lost to color or overdone effects.
The photo to the right of a young child with attitude to spare is definitely enhanced by the use of color. Using film stock good for skin tones and reds has given the photo a very punchy and 'in yer face' look. The pose has also had careful lighting applied, and I doubt that any parent has not seen a look like this, regardless of any effect used at the time or during preparation for publication.
OK. Lets assume that no trickery was employed at the point where the photo was captured. A skilled professional processor can use masks and varying exposure times while getting the image onto paper, which is further manipulated by carefully giving it the right time in the various processing baths. It can then be handed to an artist who can retouch any effect whatsoever. One can't manipulate the actual processing of transparencies in the same way as prints, other than to make time adjustments if the film stock has been 'pushed', but retouching applies to transparencies too.
Digital photography now promises every photographer in the land the chance to digitally alter and/or enhance any picture, for whatever purpose. Highly adept 'Adobe Photoshop' users can make us believe anything, and even lesser photo editor programs in the hands of outright amateurs can have us wondering. The photo to the left, of a very beautiful, self-assured young lady has elements of the 40's in that the hairstyle is of that time. Careful lighting as with any portrait is apparent, yet the overall color tone is a throw back to earlier times when Sepia tone was not just the rage, but all that was available. If one looks more closely, there is color in the eyes too.
How can a camera possibly lie, when all it does is capture a small slice of time? The possibilities are endless.