In the printing industry, bleed refers to content that extends beyond the trim line. When you cut a printed sheet to its finished size, any slight misalignment in the cut would leave a white edge — bleed prevents this by making sure content goes past where the cut will be.
Octavo’s bleed model is more flexible than what you might be used to. There are three separate concepts that work together, and understanding them will help you get the results you want. Octavo considers content bleeding out from the source margins, the placement margins, and finally the trim zone. The key distinction to note is, if the placement margins are not up against the edge of the page, you can use bleed to bring content outside the placement margins but still in the visible area of the page. Read on to see why that is useful in some situations.
If you haven’t already, read Placement and Margins first — it explains the basic placement model that bleed builds on.
This answers the question: does this source page have any content that could be used for bleed?
In the Source Page tab, the Bleed setting has three options:
This is entirely about which source content is reasonable to show. Your source PDF might have garbage at the edges that must be cut off, followed by some unimportant content that could provide bleed, followed by the content you actually care about. In that case, you’d set your source margins around the important content, and set a maximum bleed zone to include the usable-but-unimportant content while excluding the garbage.
To be clear: the source bleed setting doesn’t cause bleed to happen. It just says “this content is available if needed.”
This is the classic bleed zone — the area outside the trim line where content could go.
In the Imposition Type tab, when you’ve selected Trim mode, the Add bleed outside trim checkbox creates a bleed zone beyond the trim edges. A visual editor lets you set the distance on each side.
This zone is the space between the trim line and the cut line. When you cut your printed sheet, you cut at the trim line, and any content in this zone gets trimmed off — which is exactly the point. It’s there so that your finished page has content running right to the edge.
But just enabling a bleed zone doesn’t fill it with content. You also need your source and placement settings to actually allow content to reach this far.
This is where it all comes together. The Content Bleed setting in the Placement tab controls whether source content is allowed to extend beyond the placement margins. There are four options:
The key insight is that bleed doesn’t just mean “content outside the trim.” In Octavo, bleed is any content that extends beyond the source margins — and depending on your settings, that content might cover the gap between the placement margins and the trim edge, extend into the bleed zone beyond the trim, or both.
Consider what happens when your placement margins are inset from the trim edge (which is common — if your source pages haven’t got it baked in already, you probably want to add some margins around your content). If bleed is enabled, content that extends beyond the source margins will first have to cross the space between the placement margin and the trim edge before it reaches the bleed zone. That inset space is visible — it’s part of the finished page. So bleed content appears in the visible area of your page, not just beyond the trim.
This is the bit that works differently from other apps, and it’s intentional.
There’s no single “correct” way to use Octavo’s bleed settings. Here are a few approaches, depending on what you’re trying to achieve:
If you want bleed to work the way it does in InDesign or Illustrator — content only extends beyond the trim line, never into the visible page area — set your placement margins to zero (i.e. flush with the trim edge). Then use Beyond margins when touching for the content bleed. Because the placement margins are at the page edge, content that “touches” the margin is content that reaches the edge of the page, and bleed beyond that goes into the trim bleed zone. You’ll never get bleed content appearing within the visible page area.
Use your source margins (blue) to mark the “important bit” — the safe area — of each source page. Use placement margins (purple) to ensure this safe area is positioned with a sensible margin within the page. Then enable content bleed so that the less-important content outside the source margins can fill in the gap between the safe area and the page edge.
This approach says: “I care about this bit of the source, and I want it positioned with a nice margin. But if there’s extra content available, it can fill in the space around it.” The result is a page where the important content is well-positioned, and the margins aren’t just empty white space.
If you’re using this approach and you do want to hard-crop one or more of your source pages (for example if there’s some junk around the edge), enable Specify maximum bleed zone in the Source page tab, and use the orange bleed zone to mark out the content that you never want to see.
If you don’t need bleed, set source bleed to No bleed and content bleed to Off. Content stays within the source margins, gets placed within the placement margins, and that’s that.