Show HN: Make PDFs look scanned (CLI or in the browser via WASM) • Hacker News Board

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#11

Post by wan888888 » Sat, Jun 20, 2026, 7:59 PM UTC

I'm having a similar use case from time to time, I just use imagemagick

magick -density 150 input.pdf \ -colorspace Gray \ -virtual-pixel White -background White \ -rotate 0.7 +repage \ -attenuate 0.45 +noise Gaussian \ -blur 0x0.4 \ -brightness-contrast -5x12 \ -compress jpeg -quality 78 scanned.pdf

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#12

Post by jhbadger » Sat, Jun 20, 2026, 8:09 PM UTC

mysterydip wrote: post #5

I’m all for fun side projects, so don’t take this the wrong way. Does this have a practical use case? Like are people actually wanting to make their PDFs less legible? Usually I’m trying to do the opposite, clean up my scanned-in documents.

For some value of practical, I could see it being useful in making handouts for an RPG where the handout is supposed to be a photocopy of a section of some rare book the players need to scan for clues.

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#13

Post by carsonye » Sat, Jun 20, 2026, 8:16 PM UTC

Is there any good tool that does the opposite — turning scanned documents into clean PDFs? I’ve had that need recently.

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#14

Post by nutjob2 » Sat, Jun 20, 2026, 8:31 PM UTC

mysterydip wrote: post #5

I’m all for fun side projects, so don’t take this the wrong way. Does this have a practical use case? Like are people actually wanting to make their PDFs less legible? Usually I’m trying to do the opposite, clean up my scanned-in documents.

Typically when I send a form I will do as much as possible in a PDF editor, including the signature. Most of the world is in denial about how electronic documents, especially scanned ones, work, so you have to play along to stop them from getting upset.

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#15

Post by colesantiago » Sat, Jun 20, 2026, 8:35 PM UTC

Thank you for making this a free tool.

There are too many PDF tools that are unnecessarily paywalled, or have a paid tier that don't make any sense.

We need more tools from paid ones that should be completely free and OSS.

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#16

Post by BrandoElFollito » Sat, Jun 20, 2026, 8:44 PM UTC

mysterydip wrote: post #5

I’m all for fun side projects, so don’t take this the wrong way. Does this have a practical use case? Like are people actually wanting to make their PDFs less legible? Usually I’m trying to do the opposite, clean up my scanned-in documents.

There are countries such as France that request plenty of nonsensical handwriting with some weird also handwritten formulas. This comes from the times where graphology was a big thing in France (you would usually be required to send a handwritten letter of motivation).

Poland is also strong on that, requiring "readable handwritten signatures".

This will end when the dinosaurs that still feel it is important go away.

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#17

Post by __mharrison__ » Sat, Jun 20, 2026, 8:52 PM UTC

wan888888 wrote: post #11

I'm having a similar use case from time to time, I just use imagemagick magick -density 150 input.pdf \ -colorspace Gray \ -virtual-pixel White -background White \ -rotate 0.7 +repage \ -attenuate 0.45 +noise Gaussian \ -blur 0x0.4 \ -brightness-contrast -5x12 \ -compress jpeg -quality 78 scanned.pdf

I have something similar. Someone asked for a signed PDF. I digitally signed it and sent it to them. They said it has to be scanned. So I did some image magic fu to it to rotate it and make it look crappy. Then they accepted it.

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#18

Post by sublinear » Sat, Jun 20, 2026, 8:53 PM UTC

In the example image, the edge gradient bevels give it away.

There might be extra stuff that can be done to remedy that with this tool, but I'm not sure I'd ever use this anyway.

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#19

Post by overflowy » Sat, Jun 20, 2026, 8:58 PM UTC

sublinear wrote: post #18

In the example image, the edge gradient bevels give it away. There might be extra stuff that can be done to remedy that with this tool, but I'm not sure I'd ever use this anyway.

Everything can be adjusted, that mostly comes from `--paper-tone` being set too high.

Re: Show HN: Make PDFs look scanned (CLI or in the browser via WASM)

#20

Post by PufPufPuf » Sat, Jun 20, 2026, 8:58 PM UTC

mysterydip wrote: post #5

I’m all for fun side projects, so don’t take this the wrong way. Does this have a practical use case? Like are people actually wanting to make their PDFs less legible? Usually I’m trying to do the opposite, clean up my scanned-in documents.

I was actually required in the past to "print, sign and scan", and due to my lack of a printer I just took a picture of my signature and pasted it in. Nobody ever complained, but if they did, I imagine I'd rather use something like this than go to a copycenter to print a single sheet of paper to satisfy some arbitrary requirement.