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The other thing is that JPEG is what's called a "lossy" format. It uses algorithms to compress the information in the photograph so that instead of having information about every single pixel in the picture, it does tricks like "next 10 pixels are identical" or "keep the green levels the same for the next 20 pixels".

This is whats known as resampling, I don't know what the obsession with DPI/PPI is on the board when DPI/PPI only effects an image if it's printed (mrcakey is 100% correct), you can raise the DPI/PPI to 800 in the editor of an image thats only 200 DPI/PPI  to edit it then lower it back down to 150 and it will be clear enough to be printed on a billboard in the street, DPI doesn't effect quality whatsoever, only editing.
DPI doesn't equal resolution, if editing for a print TIFF is the best format but if showcasing online just use PNG or JPEG.
learn more here on DPI/ppi.

As I understand it reducing image size resamples the dpi, so the only way to get a pic on here for others to edit it to it's full quality is host it off site.

here's your mac driver https://esmepatterson.com/epson-perfection-v600-driver/

Did 1 for funs