When outsourcing work for a cover image for a book published on Amazon, what should the format of the image be?
I have a collection of poems written in a language other than English on Amazon, and I want to outsource the cover image to a freelancer, because it's so easy to hire someone on the Internet these days. However, I am not sure what the format of the image should be.
What file type should I use, what aspect ratio, what size? I am thinking of asking for different file size and different aspect ratio to make sure I get what I want, but I am unsure of what's the recommended format for the cover image. I have never downloaded a book from Amazon, so I have no idea how they appear, and I don't know how to take into account the different display sizes of the devices on which my book will be read.