I recently had an epub update rejected - eventually (after some back and forth to have them be explicit) being told that eBookstore (ie. Sony) will not accept books with images greater than 320000 pixels in size. I can't find any details on the Sony site or via Google etc., but I did find this (
ibooks increase size limit to 3.2 Million pixels), so maybe my distributor made a typo in their email and they really meant the iBookstore, it doesn't really matter, the result is the same.
But this seems strangely at odds with details like these:
Smashwords blog and
Smashwords FAQ for Covers recommending/suggestiong a size of 1600x2400 (3840000 pixels).
And then
Amazon KDP - Cover Image recommends a size of 1563x2500 (3907500 pixels).
In my case the cover is 1500x2400 (3600000 pixels) - which just happens to be a neat direct copy of the front of my 5"x8" 300dpi print cover (adjusted to 72dpi to keep screen stuff happier). This same cover went through without complaint twelve months ago (the update I wanted was just to the interior).
Now obviously I can reduce this image, it's not hard to do, but I am puzzled, reducing it seems contrary to the direction everything else is going. If it is just iBookstore (or eBookstore) then I don't really care, I'm happy to leave them off the distribution - if the distributor would then accept the epub. (My current one may not, but judging from what Smashwords say on the above links, they will accept it.)
Anyone shed any light on this?