Fuzzy thumbnails

[3x5]

Hi, I have noticed that thumbnails look good up to 192x144. Bigger than that, they look fuzzy. Even regenerating thumbnails doesn't help. Is there anything I can do to fix this?

[xnview]

you need to check in catalog>thumbnail size

[3x5]

Thanks so much.

edit: Although I should mention that this only sharpened some thumbs. Others stayed fuzzy. If I go into a folder and select view > update catalog from files, only some will be fixed.