FAQ

FAQ

Is the color encrypted or secret? No. "Hidden" means invisible to the eye, not protected. The format is public; anyone with Inkhue can recover the color. Don't use it to protect secrets.

Can I write on the printed page? Yes. Handwriting over the photo still decodes, and the strokes stay in the recovered picture, just as they are on the paper. Try not to write across the black frame (it usually still works, but it's the most sensitive part).

Does it work for documents, not just photos? Yes. Mostly white pages (notes, worksheets, slides) keep their highlights, colored text and charts. Inkhue notices when a page is mostly blank paper and keeps a faint dot pattern in every cell so the white areas carry data too.

I scanned it upside down / sideways. That's fine — Inkhue tries all four orientations.

I printed a normal document and scanned it, but nothing comes back. The color has to be hidden first: load the original in Hide color, print the black-and-white page Inkhue makes, then scan that page.

Does a photocopy work? Usually not: copiers re-screen the image and destroy the dot arrangement. Scan the original print.

Can I use my phone camera instead of a scanner? Not yet. The data lives in single 1/600-inch dots; phone photos blur them. A flatbed scanner (or the scanner in a multifunction printer) is needed.

Why does the recovered photo have lower resolution than my original? Each image pixel needs a 4 × 4 group of printer dots, and the color is stored at 1/8 of that. The neural refiner brings it back to 2× the cell resolution. Print larger (or use Fill the paper) to get more pixels back: a 10-inch-wide print comes back about 3000 pixels wide.

Which printers work best? Laser printers at 600 dpi on plain paper. Inkjets work, with more noise. Please share results with a print / scan report.

Can I print at a different size than 100 %? You can, but the color will probably not decode: scaling resamples the dots. Change the print width in Inkhue instead.

Do pages printed with ColorHide still work? Yes. ColorHide was renamed to Inkhue in 1.1; the on-paper format is the same.

Is it free? Can I use it commercially? Yes, under the Apache-2.0 license. It is open source so the method stays free for everyone.

Does Inkhue send my photos anywhere? No. Encoding and decoding run on your computer. The only network access is the update check against GitHub releases.