Why is a chunk of my image appearing on the previous page and how to stop it?

Question

I'm trying to design a book (my own book) and I want edge to edge images. I added bleed to the design and when I convert it to PDF it looks like this:

That's the corner between 4 pages (2 spreads) and a ribbon of image got moved to the previous page. Why is that? how do I avoid it? I imagine because of how print works, that if I go right to the edge, the image might show on the other page (whichever it is), but I still want to prevent it in the PDF.

This is how the parent page is designed:

And this is the actual page:

If I can't go right to the edge, how close can I get?

Answer 1

The short answer is that it's totally normal and not a problem.

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When you ask InDesign to add 3 mm bleed to a PDF it simply includes whatever lies within a 3 mm border around each page.

So the left page gets a 3 mm strip of the right page and vice versa.

At the print house your PDF will be processed by some imposition software which will remove the unneeded bleed towards the spine and place the pages tightly together.

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You could set the Inside bleed to 0 to avoid this:

But really it makes no difference and it's not a common thing to do. It could end up confusing the print house. In my opinion it's better to just leave it to make it clear that you remembered to include bleed.

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One thing that really confused me about your screenshot of the PDF is that you seem to enable Bleed Marks instead of Crop Marks. That makes your PDF look wrong at a first glance.

I've never understood why Bleed Marks is even an option. They just show where the bleed ends which isn't really useful information.

Instead you should only turn on Crop Marks. They show where the pages are going to actually be cut.

(See this answer where I explain printer's marks.)

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Consider this simple spread in InDesign:

It should should look like this in the PDF (3 mm bleed and Crop Marks):

If you cut the pages according to the Crop Marks you'll get the final dimensions.

It should not look like this (3 mm bleed and Bleed Marks):

To me that's just confusing because the marks do not show where the pages are to be trimmed.

Please note that technically it probably doesn't matter which marks you include. The imposition software understands the so-called boxes of the PDF and will most likely add its own marks. It's about sending a clear signal to the humans who will see the PDF.