Contents | Start | End | Previous: KB0243: Why are centred paragraphs not showing properly on Nook? | Next: KB0245: Why does Jutoh warn about line spacing?
See also:
What size should my images be?
Why does my cover image not show on a Kobo device?
How can I change the size of the cover image?
Why are some GIF or JPEG images not displayed in my Epub using Adobe Digital Editions?
How can I reduce the file size of my book?
Working with pictures in the Jutoh manual
If Reporting is set to High, Jutoh may give a tip about the cover and other images being large. Whether they are too large rather depends on the situation. Images are the biggest cause of ebook file bloat, which can cause problems such as incurring extra download charges and therefore a reduced profit margin for the author. Reducing image size can lead to benefits such as better viewer performance and quicker conversion in Jutoh (especially for Kindle books).
Sometimes a cover is provided at such a high resolution (say, 3000 px by 4000 px) that some viewers will fail to show the cover at all. You don't have to redo your cover, though; you can set the configuration option Cover image width to a suitable value, such as 800, and Jutoh will resize it on the fly as the book is generated.
For the most part, cover images don't have to be included at a very high resolution. When you upload to Amazon KDP, and some other services such as Draft2Digital, the cover in the ebook file is ignored and replaced with a higher-resolution image you provide separately. So you can afford to make the cover image low-resolution and save on file size.
The Kindle publishing guidelines distinguish between the internal cover (in the file) and the marketing cover (uploaded separately). The marketing cover should be at least 1600x2560 pixels; the guidelines have stated for some years that the internal cover is mandatory and should be at a high resolution, but in our experience this is not true and the marketing cover always replaces any internal cover.
See also How can I change the size of the cover image?
Images in the body of your book may or may not need to be high-resolution, but quite often they are inserted as provided by an artist which is fine for future-proofing but not necessary for all given ebook platforms. So you can set the configuration option Maximum image width and Jutoh will resize all your large images to be at most the given width. If you have images in your book and you find that the ebook files are much larger than you expected, you can often achieve large size savings by doing this.
By using different maximum image width values for different configurations, you can adapt image quality and size to different ebook platforms.
If your books do in fact need large images - such as fixed-layout children's story books or photography books - you can suppress the tip by setting Large images warning threshold in Preferences/Advanced to a larger value in megapixels, say 10.
Contents | Start | End | Previous: KB0243: Why are centred paragraphs not showing properly on Nook? | Next: KB0245: Why does Jutoh warn about line spacing?