Experiments with Lulu Two-piece covers

Lulu gives one set of dimensions for separate front and back cover images uploaded for conversion into a full book cover, and another set of dimensions for corresponding one-piece cover PDFs. The template for separate front and back covers includes a .375 inch bleed area on the top, bottom and outside edge of the cover image. However, the PDF that gets made from those separate front and back cover images has only .125 inch bleed area.

What happens to the extra 1/4 inch on the top, bottom and edge? This web page is an exploration of that question with respect to the Lulu 6x9 inch book.

1. Cover designed from the Lulu template.
The template is 6.375 inches by 9.75 inches. The bleed area illustrated is the .375 inch band on the top, bottom and outer edge of the 6x9 inch cover image itself. (The image below has been scaled to fit on the page--it is not intended to be used for the template.)
Scaled down cover template

From this image, I created my first test image for a front cover. Note that the ruler image was recorded and placed on the image at 300 dpi and the final image was 300 dpi. Thus the ruler is at a 1:1 scale in the full sized image. Zero inches is at the top and edge:
Test image per Lulu Template

This image was uploaded as both the front and back covers. The selection "stretch to fit" was not selected. The PDF created includes a spine and our images:
Test Cover from template for 6x9

Two things are apparent. First, the full image has been scaled down in size to fit into the PDF. The width of the PDF is two times 6.125 plus the spine width. The height of the PDF is 9.25. My experience is that the PDF is printed at a 100% scale (1:1). The book is 6x9 inches. That means that ~1/8 inch is trimmed off the sides and top of this image. Second, the material in the original template's bleed area is not fully trimmed. The shrinking of the image to fit it into the PDF size has pulled some of the bleed area into the book cover.

Lulu has built an extra level of "padding" into the specification to prevent authors from having significant elements of their art trimmed during processing. That probably works well for most authors.

What does the process do with cover images that are actually the size required to fill the PDF? Suppose we upload a similar image that is exactly 6.125 x 9.25--the size our previous image was resized to be? It is interesting to note that this image is what the specs call for when making a one-piece image (to turn into a PDF for uploading). This is our new test image:

Cover image at 6.125 x 9.25

Below is the PDF produced by the 2-piece cover process for the above image:
Cover from 6.125 x 9.25 images

Again a couple of things are apparent. The first is that the PDF is identical in size to the previous version. Our image now fills the PDF areas next the spine, without being scaled: The PDF is 9.25 inches high and the scale on our cover image shows the full 9.25 inches. Likewise the width of the cover is 6.125 inches. Again, 1/8 inch is going to be trimmed from the top, bottom and outer edges of the PDF.

Where is the center? The center of the final book cover will be about 900 pixels from the spine (or the left edge of this 6.125 x 9.250 image) and about 1388 up from the bottom of the same image.

A warning:
I have tested several covers made from one-piece PDFs that are identical in size to the PDFs produced by the Lulu cover wizard from separate covers. I have not tested these covers with a printed version. Also, the second cover image size, which was the size that Lulu once called for in the two-piece cover process, is not the size recommended by Lulu. I make no specific recommendations. I offer these tests to illustrate what the print-ready PDF will look like with two different image designs. No guarantees, no representation beyond the statement that I think that the second cover should work fine. I just do not know that for a fact. I also do not know that Lulu will not change the process requirements in the future, making this information obsolete.

View that PDF!
The best preview of your cover is the print-ready PDF available from your project's "details" page after you have completed the publishing process. Download that PDF and examine it. Consider that the spine gluing process can be somewhat variable and this will cause slight variabilities in the outer trim edge. There can be some production variabilities in the trimming of the top and bottom also. The best way to prevent the modest variations from clashing with your artwork is to move important elements in from the edges that you know will be trimmed or folded.

© 2006 by Don Campbell