New answers tagged rescaling
You could use python and one of a number of libraries, (such as SciPy/Numpy), to get a measure of the noise in the image as shown in the answer to this Stack Overflow question. Some of the same libraries and also perform image scaling and denoise e.g. SciKit Image has both denoise and scale image functions. You could also take a look at the python ...
Any photo you're never going to use again is taking up "unnecessary" space, and frankly no matter what happens to image processing technologies in the future, you're probably not going to go back and reprocess some low quality photos from 10 years ago. On the other hand, disk space is cheap (unless you're Google, Amazon, etc). Very roughly, my SLR has a ...
There might indeed be technologies (like deconvolution, eg. Focus Magic) that can restore some information from those unsharp images. This will probably improve in the future, so you might regret discarding your larger files. Plus, storage is really cheap nowadays.
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