Post processing vs 'pre-processing'

The subject of post processing, and whether it is acceptable or not, comes up frequently among photographers, both online and in person. The usual argument in favour of post processing centres around the 'good old darkroom days', and the fact that some of the best known film photographers in history were the first ones to use techniques such as dodging and burning, which have since translated to the digital world.



This is of course a valid theory, but the argument I hear less often - and one which I always explain to my clients when teaching - is that a digital camera's sensor has some technical limitations, vs what the eye/brain combination actually ‘sees’.


Take scenes with extremes of dynamic range for example – through the lens, you have to choose between exposing for the highlights in the sky or the shadows in the foreground – you can’t always do both. But you can adjust afterwards, to make the scene look far more like what your eye actually saw at the time. Whether by just reducing highlights and increasing shadows, or by merging three or more bracketed exposures.


To me this is a perfectly acceptable approach, as I’m just aiming to mitigate the limitations of the sensor technology. Not to ‘create’ something that wasn’t there originally. I'm not stripping in a totally different sky, I'm just 'recreating' what was actually there, using the data which the camera sensor captured, but which it needed a little additional work to maximise.


My most recent conversation on this subject led to an interesting debate about grad filters, and whether these are also an acceptable tool in photography. I've never heard anyone object to them as strongly as they might do to post processing - but the recent decision by the organisers of the Scottish Landscape Photographer of the Year competition to ban them for 2021 has raised the discussion to new levels.


Grad filters can also help to balance extremes of dynamic range, in the same way that post processing can – but by putting a grad filter in front of the lens when you take the shot, are you not just ‘pre-processing’ as opposed to post processing?! You’re still changing the image in some way, vs what the camera would actually have taken had you not used the grad filter - so why is that any different? And yet somehow photographers who use grad filters are not frowned upon in the same way by people who would disagree with post-processing.


Taking this to its logical conclusion, you could argue that anything which the photographer does before they take a shot - adjusting depth of field, exposure or possibly even composition - is 'pre processing' the image, and these are all perfectly normal photographic techniques. So why is it not acceptable to use computer-based post processing tools, just because they have been invented more recently? I'd be very interested to hear other people's thoughts on this!