JPEG formatting for pages
I have a coloring book for grown ups I published and all looked fine when I did my print ready copy, but upon ordering several, I realized that some of my illustrations didn't center on the pages and did a bleed print off the top. The illustrations all have borders and I want them to be centered on the pages, but I can't figure out how to do that when I upload each drawing as it's own jpeg file. Do I need to somehow save them as a certain size (like 2400x3000 dpi) or is there some critical thing I am missing? I am NOT graphic savvy... obviously. Help?