I spent the day learning the basics of setting up a print book. I’ve been avoiding thinking about this, but the time has come to face the music. Ingramspark provides a detailed File Creation Guide PDF that lays out the requirements for an acceptable submission. My pages are going to be 8-inches by 8-inches. The Guide explains that images that fill the page from border to border must extend more than .125 inches beyond the 8x8-inch square on all sides side. In other words, the image must overflow the page by .125 inches. In addition, the inner side of the page — the side that’s fastened to the binding — must have a .25in margin.
Here’s an example that shows the bleed lines for a full page image. Everything outside of the trim size will be removed. When exporting the book to PDF for actual publishing, I will turn off all of the guidelines and color samples.