Generally the answer is no. You are providing only one cover in your source -- but you can easily test how it renders in both color and greyscale. So there should be high contrast and not so much color-dependent.

The next question is required resolution and file size. Generally, Amazon and others require one high res cover but will downconvert the file size depending on the display size.

I'm not an expert on accessibility (and am certainly no artist), but know a lot about formatting and what is possible for ebooks. I work often with graphic designers. The key thing is reducing the key elements in the cover -- unless you are going with something that looks like a picture.

By the way, from a marketing perspective it is crucial to have only one cover for a ebook. Even if a second cover is a simplified view of the original cover, it can confuse customers and ebook distributors.

One thing you should absolutely consider is how the cover appears in a thumbnail. I wrote a little piece about ebook covers and noticed these constraints on ebook deal ads.

One last thing. A common way to advertise your ebooks is through ebook newsletters. Each daily newsletter normally brings 20+ book ads with the ebook cover. The art included with these newsletters tends to be small, so you should make sure that a thumbnail conveys the cover concept adequately. I haven't verified these dimensions, but a quick check in my browser reveals that Bookbub uses 215 pixels, Bookgorilla uses 180 pixels, Bargainbooksy uses 250 pixels, and Fussy Librarian uses 170 pixels...Typically on Amazon, the ebook covers appear as 150-175 pixels wide on the search results page and 300 pixels wide on the ebook product page.

Generally the answer is no. You are defining only one cover in your source -- but you can easily test how it renders in both color and greyscale. So it should be high contrast and not so much color-dependent.

The next question is required resolution and file size. Generally, Amazon and others require one high res cover but will downconvert the file size depending on the display size.

I'm not an expert on accessibility (and am certainly no artist), but know a lot about formatting and what is possible for ebooks. The key thing is reducing the key elements in the cover -- unless you are going with something that looks like an actual scenic view. Even that is hard to pull off (although in scifi, it is more commonly done).

By the way, from a marketing perspective it is crucial to have only one cover for a ebook. Even if a second cover is a simplified view of the original cover, it can confuse customers and ebook distributors.

One thing you should absolutely consider is how the cover appears in a thumbnail. Full scenery in a cover often does not work well in thumbnails. I wrote a little piece about ebook covers and noticed these constraints on ebook deal ads.

One last thing. A common way to advertise your ebooks is through ebook newsletters. Each daily newsletter normally brings 20+ book ads with the ebook cover. The art included with these newsletters tends to be small, so you should make sure that a thumbnail conveys the cover concept adequately. I haven't verified these dimensions, but a quick check in my browser reveals that Bookbub uses 215 pixels, Bookgorilla uses 180 pixels, Bargainbooksy uses 250 pixels, and Fussy Librarian uses 170 pixels...Typically on Amazon, the ebook covers appear as 150-175 pixels wide on the search results page and 300 pixels wide on the ebook product page.