How it works
The tool scans each pixel and makes anything lighter than the threshold transparent while darkening the ink to a solid black. The result is a PNG with a see-through background that drops cleanly onto PDFs, Word documents and e-signature fields. Everything runs in your browser.
Getting a clean signature
Sign with a dark pen on plain white paper, photograph it in good light without shadows, and crop close to the signature. If faint background shows through, lower the threshold; if thin strokes disappear, raise it. 180–200 works for most photos.
Where to use it
Signing PDF forms, government applications that ask for a signature image (often 140×60 px, under 20 KB), email signatures and invoices. For size-limited portals, run the PNG through the Resize image tool afterwards.
Frequently asked questions
Does it work on blue ink?
Yes. Any ink darker than the threshold is kept and converted to black.
Can I keep the original ink colour?
This version outputs black for maximum compatibility with forms.
What format is the output?
PNG with transparency, which is what most e-signature and PDF tools require.