I upload my photos for each postcard. The quality always ends up compressed and bad. Which is strange because the photo I take is high quality. I don’t scan the postcards, only a photo. I don’t know what I’m doing wrong.
If the cards in your profile were uploaded by you, than at least here on my screen I see no problem. Quality looks fine.
Maybe you could make the pictures/cards smaller on your own (pixelsize around 350 for the smaller size), then the software doesn’t have to/won’t change the look.
(Of course, the galleries don’t show download-printable versions (per se), otherwise we’d be even more in the copyright-violations-area)
I also photograph my postcards, but then edit for the best looks, and scale the image to 500 pixels on the long side, and make sure the shorter side is at least 300 pixels. I think these are the minimum sizes the system will accept, and images are scaled to fit.