Print quality: 100% K, vector, size

Is my barcode really vector? How to check in Acrobat and Illustrator

By Marko Markovic, prepress specialist · Updated 10 October 2026 · 4 min read

Vector is a recommendation, not a rule

KDP prefers vector and accepts raster at 300 PPI; IngramSpark accepts vector or high-quality raster. So a raster barcode is not automatically wrong. Vector is recommended because it has no resolution to get wrong and survives scaling. The checks below tell you which one you have, and whether it is clean.

Why "PDF" does not mean "vector"

A PDF is a container. It can hold vector shapes, text and pictures. Many barcode files are a PNG wrapped in a PDF or an EPS: the file name says PDF or EPS, the content is pixels. The only way to know is to look inside.

Check 1: the zoom test (any PDF viewer)

1. Open the barcode PDF, or your final cover PDF.
2. Zoom to 1600% or more on the edge of a bar.
3. Look at the edge.

The zoom test is quick but not proof: a very high-resolution image can look sharp for a long time. Use check 2 for certainty.

Check 2: Outline view in Illustrator

1. Open the PDF in Illustrator (File, Open).
2. Switch to Outline view with View, Outline (Ctrl+Y on Windows, Cmd+Y on Mac).
3. Look at the result. Vector: each bar appears as a thin rectangle outline, and the digits appear as letter outlines. Raster: you see one box, often with a cross through it, where the image sits, and no bars.
4. Press Ctrl+Y or Cmd+Y again to return to Preview.

You can also open the Links panel or Document Info: an embedded image in the barcode is a sign it is raster.

Check 3: the inks, in Acrobat Pro

This is the check printers care about most.

1. In Acrobat Pro, open the PDF and choose Print Production, then Output Preview.
2. Set Preview to Separations.
3. Uncheck Cyan, Magenta and Yellow, keep Black on.
4. The barcode should still be complete, with no part missing.
5. Now turn Black off and the others on: the barcode should disappear completely.

If parts of the barcode show on cyan, magenta or yellow, it is not 100% K. Why that matters.

In Illustrator, Window, Separations Preview gives the same view. Acrobat's Output Preview is part of Acrobat Pro; the free Reader does not have it.

Check 4: the final cover PDF, not the barcode file

Run checks 1 and 3 again on the exported cover PDF you are going to upload. A clean barcode can be damaged on the way:

• the cover was exported with color conversion and the black became four inks;
• the whole cover was flattened into one image;
• the barcode was placed as a screenshot instead of the PDF.

KDP says the barcode must not be flattened into the main cover as one image, and prefers vector.

What a correct barcode file looks like

• Bars and digits are vector shapes (no images).
• One ink: Black, 100%.
• White areas are no ink, not white ink.
• Placed at 100%.

Barcode Rocket's PDFs are made this way. Download a sample from the home page, open it, and run the four checks yourself.