Out of black ink? Convert a PDF or image to a dark color your printer can still print — everything happens in your browser, files never leave your device.

📄 Drop a PDF / PNG / JPG here

or click to choose a file · everything runs locally

Ink Blue — default Red Magenta Dark green

Quality 150 DPI — fast, small 300 DPI — recommended 600 DPI — max (slow, heavy)

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Out of black ink but need to print a shipping label or document? The tool above converts a PDF or image to a dark ink color of your choice so your printer skips the empty black cartridge. Files never leave your device.

Mapping: white stays white (255,255,255) (no ink), black becomes the full ink color, greys become light tints. Only dark inks are offered — blue, red, magenta, dark green — so the page still reads as black/dark-grey if someone photocopies it in B&W. The output PDF keeps the original page size.

How it works & privacy

1. Your PDF is rasterized with pdf.js at the DPI you pick.
2. Each pixel's luminance L = 0.299·R + 0.587·G + 0.114·B is computed (same as Pillow's convert("L")).
3. Each pixel is remapped so white stays white and black becomes the full ink color: out = 255 − (255 − ink)·(255 − L)/255 (for blue ink that's exactly (L, L, 255)).
4. Pages are re-assembled into a PDF with pdf-lib, preserving each page's physical size in points.

Privacy: no server, no upload — open DevTools → Network and watch: the only requests are the CDN libraries. Note the output is rasterized (text is no longer selectable) — ideal for labels and forms.