This book will be published through Amazon Kindle, Barnes&Noble Nook, and possibly Smashwords & Lulu.
Here are the KINDLE specifications:
Amazon KDP applies additional compression to images when displaying them on its website. For best results, images should be uploaded with minimal compression.
• JPEG (Joint Photographic Experts Group)
• TIFF (Tagged Image File Format)
Minimum 500 x Maximum 1280 pixels
Recommendations for the size of your cover art:
• Minimum of 500 pixels, horizontally
• Maximum of 1280 pixels, vertically
Save at 72 dots per inch (dpi) for optimal viewing on the web. Cover art with white or very light backgrounds can seem to disappear against the white background. Adding a very narrow (3-4 pixel) border in medium grey will define the boundaries of the cover.
Here are the NOOK Specifications: Your cover image must be a .JPG or .JPEG file with a file size between 5KB and 2MB. The sides must be between 750 pixels and 2000 pixels in length.