@richo - maybe you could use the Unpack tool on the ePub. You will probably need to add Unpack to a toolbar or menu. Explode the book (the tool will put the components into a temporary location), use an image editor to upscale, sharpen ... the images, and then Rebuild the book.
I found an image about the same size as the ones you have (400x200), and I resized it to 1200x1600 using Lancoz resampling. The two images are attached.
If there were a more than a handful of images, and they were 'important' - e.g. if it was a cook book or a travelogue I would wince whenever I saw the resized images on a tablet.
I would even consider looking for an epub edition with larger images and get calibre to convert to a Kindle PW compatible format with downscaled images.
BR
Last edited by BetterRed; 05-28-2017 at 05:07 AM.
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