I am wanting to send some pictures to my cover designer I plan on taking with my iPhone's camera. Smashword's requirements are listed here. I can't take a photo and then expand it, which could cause pixelation. I'm interested in using the same image to put on the physical cover for Amazon Create Space.
Also, I am completely blind and use a screen reader. Fortunately, Windows Paint is pretty accessible, but I'm afraid I can't do much with it, so I'm leaving it up to the cover designers.
All versions of the iPhone 8 have a 12 MP rearward facing camera with a 4:3 aspect ratio. That figures to about 3000 pixels x 4000 pixels in vertical (portrait) orientation. That's more than enough to furnish an image that is 2,400 pixels high and 1,600 pixels wide as recommended by Smashwords. It is just over twice as wide as the stated minimum width requirement of 1,400 pixels.
Beyond that, it's only a question of producing an image that is both attractive and appropriate for your book and its subject matter. If you're not sure how to go about that, maybe you could enlist a friend to help?
The only requirement for cover image is that your editor/publisher/cover designer like it. You should talk to them about expectations in terms of resolution, file format and such.
Modern iPhones have very high-quality cameras compared to old digital cameras. And even those were good enough to make high-quality prints. For example, Ken Rockwell sold some images to McDonalds to make billboards. He used Nikon D7000 from 2010 that costs $200 now
