If you want your image or background color to reach all the way to the edge of the printed page or cover you must design to the bleed line. If using Blurb's PDF uploader a correctly-designed bleed will reach past the black dotted trim line and go to the outer edge of the grey shaded area.
Here's an example of a correctly designed full-bleed cover layout in the PDF uploader preview:
...and a close-up of the same layout. Notice how the blue background goes all the way to the outer edge of the grey shaded area:
Below is an example of an incorrectly designed bleed as seen in the uploader preview. It doesn't reach all the way to the outer edge of the grey shaded area. (In this case it only reaches to the black dotted trim line, and would print with a thin white edge all around).
Here's a close-up view of the incorrectly designed bleed:
|Be sure to carefully review your PDF before you upload it. Then preview it again after uploading, using the PDF uploader preview. And if you're placing a large order it's always a good idea to order and review a single proof copy first.|