Many factors affect the true resolution of an image — the actual detail resolvable — including lens quality, sensor size and technology, noise and noise reduction, motion blur and camera technique, and even just the subject. It's essential to have enough pixel resolution to capture this, but more than that seems like waste.
I have a lot of pictures from my smartphone or my sports camera that may just have too many pixels. Is there a software way to detect this "overweight" and reduce it? (Preferably, command line on Linux.)
If there is no existing tool, I'll try a script or a Python program, but then the hardest part would be "define picture overweight": I can easily fetch resolution and other values from
exiftool, but I would need a parameter like "how much are contiguous pixel similar", which, when very high, would mean that resolution is too high (i.e. can be reduced without perceptible loss of quality). Any hint here?