What is PDF preflight?
Short answer
PDF preflight is the process of checking a PDF against the technical requirements of a print workflow before production. It reports where the file does not meet those requirements — it does not by itself fix them.
What a preflight check looks at
A preflight profile is a list of conditions with tolerances. Each condition is checked and reported with a severity, so a missing 3 mm bleed and an unembedded font are not treated as equally urgent.
- Page size, trim box and bleed box against the ordered size
- Colour spaces present, and whether they match the output intent
- Effective resolution of every placed image at final size
- Font embedding and subsetting
- Live transparency, blend modes and overprint settings
- Compliance with a PDF standard such as PDF/X-4
Severity is the useful part
A good preflight result distinguishes an error, which stops the job, from a warning, which needs a decision, from information worth recording. Without that distinction every file looks equally broken, and operators start ignoring the report — which defeats the purpose of running it.
ERROR 3 images in RGB · output intent is CMYK ERROR Bleed 0 mm · profile requires 3 mm WARNING Effective DPI 96 · minimum 150 INFO Live transparency present · permitted
Where preflight ends
Preflight tells you the state of the file. It does not decide whether the job can run, and it does not repair anything. That gap is where most of the manual work sits: someone still has to convert the colour, generate the bleed, decide whether 96 dpi is acceptable at this size, and write to the customer if it is not.
How Prepta handles it
Prepta runs preflight as one step in a longer sequence. It first classifies the likely source of the file, because a Canva export and a professionally prepared PDF fail the same checks for different reasons. It then preflights against your production profile, applies the repairs that profile marks safe, validates the output, and escalates the rest with a recommendation.