Preflight Check
Preflight is the last quality-control step before a PDF is sent to print. Learn what is checked and how to fix common errors.
Preflight Check
Preflight is the final quality gate before a PDF enters production — much like the pre-flight checklist a pilot completes before takeoff. Catching errors here costs a fraction of what they cost after printing.
The 1-10-100 Rule
| Stage | Cost | Action |
|---|---|---|
| Catch error at design stage | $1 | Fix on screen |
| Catch error at preflight | $10 | Return file to customer |
| Catch error after printing | $100 | Wasted paper, ink and time |
What Gets Checked
1. Image Resolution (DPI)
- Web standard: 72 DPI — too low for print, will appear blurry
- Print standard: 300 DPI minimum
- Files below 200 DPI trigger a Low Resolution error
Pixelation Risk
Images below 200 DPI produce visible pixelation in print. The system flags these as a blocking error.
2. Bleed and Safe Zone
- Bleed: Background must extend 3 mm beyond the trim line so there are no white edges after cutting
- Safe zone: Keep all important text and logos at least 5 mm from the trim line
3. Font Embedding
All fonts must be embedded in the PDF. If a font is not embedded the print shop's system may substitute a different typeface.
4. Colour Mode
- RGB — for screens (Red, Green, Blue light)
- CMYK — for print (Cyan, Magenta, Yellow, Black ink)
RGB files are accepted but colours may shift during conversion, especially bright oranges and neons.
5. Document Size
Does the file size match the product ordered? An A4 PDF submitted for an A5 order is a blocking error.
6. Page Count
Booklets and books must have a page count divisible by 4 (required for folding and binding).
Traffic Light System
NowToPrint checks files against ISO 12647 and assigns one of three results:
| Result | Colour | Meaning | Action |
|---|---|---|---|
| Pass | Green | File is perfect | Send to print |
| Warning | Yellow | Minor risk (e.g. 220 DPI image) | Can print with your approval |
| Error | Red | Critical issue (e.g. missing bleed) | Must fix before printing |
PDF/X Standards
The system automatically converts files to the appropriate PDF/X standard:
- PDF/X-1a: Safest, widest compatibility. Flattens transparency. Minimises risk.
- PDF/X-4: For modern RIPs. Preserves transparency and layers, richer colours.
Knowledge Check
التحقق من المعرفة
When does the Preflight check run?
Which conditions trigger a Red (Error) result? (Multiple)
What is the difference between RGB and CMYK?
Common Errors and Fixes
"Low Resolution Images Detected"
Problem: Images below 200 DPI.
Fix: Source the original high-resolution image, replace in design, or reduce the element size.
"Missing Bleed"
Problem: Background does not extend beyond the trim line.
Fix: In InDesign/Illustrator set Document Bleed to 3 mm, extend background, re-export.
"Fonts Not Embedded"
Problem: Custom fonts not embedded in PDF.
Fix: In export settings enable "Embed All Fonts", or outline the text before exporting.
"RGB Colour Space Detected"
Problem: Images or colours in RGB mode.
Fix: In Photoshop: Image → Mode → CMYK. Check for colour shift, re-export.
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