| name | color-to-grayscale |
| description | Convert a color PDF to grayscale (black-and-white) for monochrome digital printing — saves toner and avoids color-mismatch issues. Triggers on phrases like "convert PDF to grayscale", "make it black and white", "remove color from PDF", "monochrome PDF". |
Convert PDF to Grayscale
Strip color from every page of a PDF, producing a grayscale-only output suitable for monochrome printing.
Inputs
- Input PDF path (required).
- Output path (optional) — defaults to
<input>-grayscale.pdf.
Tooling
Use ghostscript with the pdfwrite device and a grayscale color conversion strategy. This is the most reliable method — it converts both raster images and vector content.
Recipe
gs -sOutputFile=output.pdf \
-sDEVICE=pdfwrite \
-sColorConversionStrategy=Gray \
-sProcessColorModel=DeviceGray \
-dCompatibilityLevel=1.4 \
-dNOPAUSE -dBATCH \
input.pdf
Workflow
- Verify input exists.
- Confirm
gs is installed.
- Run the conversion.
- Spot-check by rendering page 1 to PNG and confirming no color channels:
gs -sDEVICE=png16m -r72 -o /tmp/check.png -dFirstPage=1 -dLastPage=1 output.pdf
- Report file size delta — grayscale PDFs are usually significantly smaller.
Output
Grayscale PDF written to the requested path. Original is not modified.
Caveats
- If the source PDF embeds CMYK or spot colors, the conversion is still safe but may flatten subtle tones.
- Text remains crisp; embedded JPEGs are re-compressed as grayscale JPEGs.
