| name | flatten-transparency |
| description | Flatten transparency in a PDF — eliminates banding, color shifts, and weird overprint artifacts on older or cheaper digital printers. Triggers on phrases like "flatten transparency", "fix banding on print", "flatten layers in PDF". |
Flatten Transparency
Convert transparent overlays, alpha blends, and soft masks into solid raster/vector output. Many digital printers (especially older RIPs or budget office units) mishandle live transparency, causing banding or color shifts.
Inputs
- Input PDF path (required).
- Quality (optional) —
print (default, 300 DPI raster regions), screen (150 DPI, smaller files), prepress (highest fidelity).
- Output path (optional) — defaults to
<input>-flat.pdf.
Tooling
Ghostscript with pdfwrite and -dCompatibilityLevel=1.3 flattens automatically because PDF 1.3 has no live transparency model.
Recipe
gs -o output.pdf \
-sDEVICE=pdfwrite \
-dCompatibilityLevel=1.3 \
-dPDFSETTINGS=/printer \
-dEmbedAllFonts=true \
-dSubsetFonts=true \
-dNOPAUSE -dBATCH \
input.pdf
Compatibility=1.3 forces flattening. /printer tunes raster quality for print.
Diagnosis (when to use)
Symptoms that suggest transparency is the culprit:
- Soft drop-shadows print as banded gradients.
- Logos with alpha look milky or washed out.
- Colors near transparent overlays shift.
Probe for transparency:
mutool show input.pdf grep -i "/SMask\|/CA\|/ca\b\|/BM"
Hits → live transparency present.
Caveats
- Flattening rasterizes affected regions — file size may grow.
- Text inside flattened regions may become a raster image and lose searchability/selectability. Keep the original.
Output
Flattened PDF. Original preserved — flattening is destructive in the sense that liveness is lost.
